The developing role of gas in decarbonizing China's energy system:system analysis of technical, economic and environmental improvements of LNG and low carbon gas supply chains and infrastructure

The gas system in China is essential for an energy transition towards a low-carbon future. The optimization of gas supply chains and gas infrastructure deployment is crucial for energy-saving, cost-saving, and GHG emissions mitigation. In the short term, natural gas can act as a transition fuel by replacing oil and coal in especially power and transport sectors. In the long term, gradually replacing natural gas with low-carbon gas can secure the role of the gas infrastructure in a low carbon energy system. As China is undergoing an energy transition from a coal dominated energy system to a low-carbon energy system, the main objective of this thesis is to investigate how gaseous energy carriers and the NG infrastructure can be used in the most efficient way for a low-carbon energy system in China towards 2050. In this thesis, the potential role of LNG in the short term and low-carbon gases in the long term for a low-carbon energy system with infrastructure deployment pathway in China are investigated by assessing the energy efficiency, GHG emissions, and costs of the supply chains

West meets East: An exploration of the ways American university development officers can build guanxi with Chinese parents

Because philanthropic support from alumni and their families is an important source of revenue for American colleges and universities, identifying ways to connect with Chinese students and cultivate philanthropic support from their parents is an essential component of fundraising efforts. In this study, I explored how American university advancement officers could employ guanxi to cultivate relationships with Chinese parent donors in order to increase U.S. higher education philanthropy efforts. The concept of guanxi, an important aspect of building and sustaining relationships in China, served as the focus for understanding Chinese parents’ connections with their children’s American universities. I employed a qualitative collective case study design using purposeful criterion sampling and conducted research with seven participants. The research findings inform the practice of American university fundraising. The researcher generated specific strategies for American university development officers to build and cultivate guanxi with Chinese parents in order to receive more donations from them. Recommendations for further research are also provided

Traveling-Wave-Based Fault Location in Electrical Distribution Systems With Digital Simulations

Traveling-wave-based fault location in electrical distribution systems is an important safeguard for the distribution network reliability. The effectiveness of the methods is verified directly in power grid in the early stages, while different fault types can't appear in a short time. And normal dynamic physical simulation cannot meet the teaching demand either because of the limitation of transmission line model and other factors. So PSCAD/EMTDC and MATLAB are used to illustrate the the fault location methods in this paper, which can promote the traveling-wave-based fault-location technology. Meanwhile, the traveling-wave-based fault-location method based on characteristic frequencies is analyzed in this paper

Potential role of natural gas infrastructure in China to supply low-carbon gases during 2020–2050

As natural gas (NG) demand increases in China, the question arises how the NG infrastructure fit into a low greenhouse gas (GHG) emissions future towards 2050. Herein, the potential role of the NG infrastructure in supplying low-carbon gases during 2020–2050 for China at a provincial resolution was analyzed for different scenarios. In total, four low-carbon gases were considered in this study: biomethane, bio-synthetic methane, hydrogen, and low-carbon synthetic methane. The results show that the total potential of low-carbon gas production can increase from 1.21 EJ to 5.25 EJ during 2020–2050, which can replace 20%–67% of the imported gas. In particular, Yunnan and Inner Mongolia contribute 17% of China's low-carbon gas production. As the deployment of NG infrastructure can be very different, three scenarios replacing imported pipeline NG were found to reduce the expansion of gas infrastructure by 35%–42%, while the three scenarios replacing LNG imports were found to increase infrastructure expansion by 31%–53%, as compared to the base case. The cumulative avoided GHG emissions for the 6 analyzed scenarios were 6.0–8.3 Gt CO2. The GHG avoidance costs were highly influenced by the NG price. This study shows that the NG infrastructure has the potential to supply low-carbon gases in China, thereby significantly reducing GHG emissions and increasing both China's short- and long-term gas supply independence

Comprehensive review of current natural gas liquefaction processes on technical and economic performance

This paper provides a quantitative technical and economic overview of the status of natural-gas liquefaction (LNG) processes. Data is based on industrial practices in technical reports and optimization results in academic literature, which are harmonized to primary energy input and production cost. The LNG processes reviewed are classified into three categories: onshore large-scale, onshore small-scale and offshore. These categories each have a different optimization focus in academic literature. Besides minimizing energy consumption, the focus is also on: coproduction for large-scale; simplicity and ease of operation for small-scale; and low space requirement, safety and insensitivity to motion for offshore. The review on academic literature also indicated that optimization for lowest energy consumption may not lead to the lowest production cost. The review on technical reports shows that the mixed-refrigerant process dominates the LNG industry, but has competitions from the cascade process in large-scale applications and from the expander-based process in small-scale and offshore applications. This study also found that there is a potential improvement in adopting new optimization algorithms for efficiently solving complex optimization problems. The technical performance overview shows that the primary energy input for large-scale processes (0.031–0.102 GJ/GJ LNG) is lower than for small-scale processes (0.049–0.362 GJ/GJ LNG). However, the primary energy input for identical processes do not necessarily decrease with increasing capacity and the performance of major equipment shows low correlation with scale. The economic performance overview shows specific capital costs varying significantly from 124 to 2255 $/TPA LNG. The variation could be, among others, caused by the different complexities of the facility and different local circumstances. Production cost, excluding feed costs, varies between 0.69 and 4.10$/GJ LNG, with capital costs being the dominant contributor. The feed cost itself could be 1.51–4.01 $/GJ LNG, depending on the location. Lastly, the quantitative harmonization results on technical and economic performance in this study can function as a baseline for the purpose of comparison

Technical and economic optimization of expander-based small-scale natural gas liquefaction processes with absorption precooling cycle

The objective of this study is to investigate potential technical and economic performance improvement for expander-based natural gas liquefaction processes in small-scale applications. Four expander-based processes were optimized and compared in this study, including conventional single nitrogen expansion process without (SN) and with ammonia absorption precooling (SNA), and single methane expansion process without (SM) and with ammonia absorption precooling (SMA). A two-phase expander is utilized in the methane expansion process to enable liquid generation at the expander outlet. The optimization was done with two objective functions: minimization of specific energy consumption and minimization of production cost. The energy and cost analyses were performed for the four processes by comparing optimization results. Lastly, exergy losses in the main equipment were analyzed. The results show that the ammonia precooling cycle reduces energy consumption and production cost by 26–35% and 13–17%, respectively. The single methane process with precooling is the most promising process, which has 28–48% lower energy consumption and 13–43% lower production cost compared to those of the other three processes. Results also indicate that the best techno-economic performance is obtained with objective of minimizing production cost and not with the commonly used energy-related objective

Techno-economic and life cycle greenhouse gas emissions assessment of liquefied natural gas supply chain in China

This study assessed the techno-economic performance and life cycle greenhouse gas (GHG) emissions for various liquefied natural gas (LNG) supply chains in China in order to find the most efficient way to supply and use LNG. This study improves current literature by adding supply chain optimization options (cold energy recovery and hydrogen production) and by analyzing the entire supply chain of four different LNG end-users (power generation, industrial heating, residential heating, and truck usage). This resulted in 33 LNG pathways for which the energy efficiency, life cycle GHG emissions, and life cycle costs were determined by process-based material and energy flow analysis, life cycle assessment, and production cost calculation, respectively. The LNG and hydrogen supply chains were compared with a reference chain (coal or diesel) to determine avoided GHG emissions and GHG avoidance costs. Results show that NG with full cryogenic carbon dioxide capture (FCCC) is most beneficial pathway for both avoided GHG emissions and GHG avoidance costs (70.5–112.4 g CO2-e/MJLNG and 66.0–95.9 $/t CO2-e). The best case was obtained when NG with FCCC replaces coal-fired power plants. Results also indicate that hydrogen pathways requires maturation of new technology options and significant capital cost reductions to become attractive

Enhancement of Heat-Cured Cement Paste with Tannic Acid

The Improvement of Cement-Based Materials\u27 Performance by Natural Organic Compounds Can Greatly Promote the Green and Sustainable Development of the Construction Industry. However, Such Compounds Are Not Widely Used Yet Because of their Retarding Effect on Cement. in This Study, the Retardation Effect of Tannic Acid (TA, a Well-Known Retarding Compound) is overcome and the Enhancing Effect is Achieved by Adding Less Than 0.1% Content and Curing Samples in Thermal Regime. Then the Mechanism of TA Enhancing Heat-Cured Cement Pastes is Studied Systematically. Mechanical Properties Results Suggest that Addition of 0.025% TA Can Reduce the Compressive and Flexural Strengths of Cement Pastes by Up to 3.4% and 17.1% under Normal Curing Regime at 3 Days, But Enhance These Two Strengths by More Than 11.4% and 34.6% after Thermal Curing, Respectively. XRD Patterns and TGA Analysis Indicate that, under Thermal Curing Regime, 0.025% TA Can Improve the Hydration Degree of Cement Where the Bound Water Content is Increased by 21.4%. SEM Observations and MIP Results Show that TA Can Compact the Microstructure and the Porosity is Decreased by More Than 7.0%. Furthermore, FTIR Spectrums Prove that TA Can Bond with Hydration Products. Molecular Dynamics Simulation Demonstrates that TA Cross-Links with Calcium Silicate Hydrates (C–S–H) through Ionic and Hydrogen Bonds, Which Could Increase the Tensile Strength by 12.5% and the Ultimate Strain by 100%

Wavelet Power and Shannon Entropy Applied to Acoustic Emission Signals for Corrosion Detection and Evaluation of Reinforced Concrete

Acoustic emission (AE) signals detected from corrosion test on a steel reinforced concrete beam subjected to the coupling effects of corrosive wet-dry cycles and static load are analyzed by power spectral density, wavelet transform, and Shannon entropy. The degradation process of the corroded reinforced concrete beam can be divided into four stages on the basis of the accumulated event number (AEN). Due to the difference of material properties, steel reinforcement and concrete matrix have distinguished AE features. The time-frequency characteristics of AE signals can reflect the microstructural degradation mechanism of steel corrosion and concrete cracking. The corrosion evaluation entails investigating the evolution of the wavelet power mathematically by Shannon entropy. The frequency-entropy clearly exhibits the relative power distribution of AE signal in a certain frequency region. With the accumulation of steel corrosion and concrete deterioration, the increment of the overall entropy integration is considerably apparent. The variation of frequency-entropy curve reveals the corrosion revolution of the reinforced concrete members under static load, which is represented by a transforming from corrosion-induced micro cracking to load-induced localized cracking

LLMVA-GEBC: Large Language Model with Video Adapter for Generic Event Boundary Captioning

Our winning entry for the CVPR 2023 Generic Event Boundary Captioning (GEBC) competition is detailed in this paper. Unlike conventional video captioning tasks, GEBC demands that the captioning model possess an understanding of immediate changes in status around the designated video boundary, making it a difficult task. This paper proposes an effective model LLMVA-GEBC (Large Language Model with Video Adapter for Generic Event Boundary Captioning): (1) We utilize a pretrained LLM for generating human-like captions with high quality. (2) To adapt the model to the GEBC task, we take the video Q-former as an adapter and train it with the frozen visual feature extractors and LLM. Our proposed method achieved a 76.14 score on the test set and won the first place in the challenge. Our code is available at https://github.com/zjr2000/LLMVA-GEBC .Comment: Winner solution to Generic Event Boundary Captioning task in LOVEU Challenge (CVPR 2023 workshop