76 research outputs found
Oxide perovskite BaSnO3: A promising high-temperature thermoelectric material for transparent conducting oxides
The new technology of energy conversion must be developed to ensure energy
sustainability. Thermoelectric (TE) materials provide an effective means to
solve the energy crisis. As a potential TE candidate, the TE properties of
perovskite have received extensively attention. We here investigate the TE
transport properties of the transparent conducting oxide (TCO) BaSnO3 by
first-principles calculations. We find that the BaSnO3 perovskite exhibits
outstanding dynamic and thermal stabilities, which provide excellent electronic
and thermal transport properties simultaneously. These properties contribute to
the remarkable Seebeck coefficient and power factor, which gives rise to the ZT
of n-1.03 and p-3.64 at 900 K. Additionally, doping and nanostructure open
prospects for effectively improving the TE properties of BaSnO3. Our work
provides a basis for further optimizing the TE transport properties of cubic
BaSnO3 and may have worthwhile practical significance for applying cubic
perovskite to the high-temperature thermoelectric field.Comment: 29 pages,6 figures,1 tabl
Can Large Language Models Understand Real-World Complex Instructions?
Large language models (LLMs) can understand human instructions, showing their
potential for pragmatic applications beyond traditional NLP tasks. However,
they still struggle with complex instructions, which can be either complex task
descriptions that require multiple tasks and constraints, or complex input that
contains long context, noise, heterogeneous information and multi-turn format.
Due to these features, LLMs often ignore semantic constraints from task
descriptions, generate incorrect formats, violate length or sample count
constraints, and be unfaithful to the input text. Existing benchmarks are
insufficient to assess LLMs' ability to understand complex instructions, as
they are close-ended and simple. To bridge this gap, we propose CELLO, a
benchmark for evaluating LLMs' ability to follow complex instructions
systematically. We design eight features for complex instructions and construct
a comprehensive evaluation dataset from real-world scenarios. We also establish
four criteria and develop corresponding metrics, as current ones are
inadequate, biased or too strict and coarse-grained. We compare the performance
of representative Chinese-oriented and English-oriented models in following
complex instructions through extensive experiments. Resources of CELLO are
publicly available at https://github.com/Abbey4799/CELLO
Optimization of Guide Vane Closing Schemes of Pumped Storage Hydro Unit Using an Enhanced Multi-Objective Gravitational Search Algorithm
The optimization of guide vane closing schemes (OGVCS) of pumped storage hydro units (PSHUs) is a cooperative control and optimal operation research field in renewable energy power generation technology. This paper presents an OGVCS model of PSHUs considering the rise rate of the unit rotational speed, the specific node pressure of each hydraulic unit, as well as various complicated hydraulic and mechanical constraints. The OGVCS model is formulated as a multi-objective optimization problem to optimize conflicting objectives, i.e., unit rotational speed and water hammer pressure criteria. In order to realize an efficient solution of the OGVCS model, an enhanced multi-objective bacterial-foraging chemotaxis gravitational search algorithm (EMOBCGSA) is proposed to solve this problem, which adopts population reconstruction, adaptive selection chemotaxis operator of local searching strategy and elite archive set to efficiently solve the multi-objective problem. In particular a novel constraints-handling strategy with elimination and local search based on violation ranking is used to balance the various hydraulic and mechanical constraints. Finally, simulation cases of complex extreme operating conditions (i.e., load rejection and pump outage) of a ‘single tube-double units’ type PSHU system are conducted to verify the feasibility and effectiveness of the proposed EMOBCGSA in solving OGVCS problems. The simulation results indicate that the proposed EMOBCGSA can provide a lower rise rate of the unit rotational speed and smaller water hammer pressure than other methods established recently while considering various complex constraints in OGVCS problems
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