196 research outputs found
Microstructural evolution in 9 wt.% Cr power plant steels
High chromium ferritic steels such as Grade 91 and Grade 92 are extensively used in the
power plant industry. Components made from these types of steels, including headers, steam
pipes and tubes, are required to provide reliable service at high pressures (20-30 MPa) and
temperatures (550-610°C) for several decades. However, in order to further improve the
thermal efficiency of the power plant, the future operation temperature for the ferritic steels
needs to be elevated to 650°C. Therefore, the current research project focuses on the
examination of recently developed MarBN type steels (Martensitic steel strengthened by
Boron and Nitrides) and four Grade 92 derivatives in order to evaluate their suitability for
650°C application, and also to assess their creep strength from a microstructural point of
view. [Continues.
Capacity Planning with Financial and Operational Hedging in LowâCost Countries
The authors of this paper outline a capacity planning problem in which a risk-averse firm reserves capacities with potential suppliers that are located in multiple low-cost countries. While demand is uncertain, the firm also faces multi-country foreign currency exposures. This study develops a mean-variance model that maximizes the firmâs optimal utility and derives optimal utility and optimal decisions in capacity and financial hedging size. The authors show that when demand and exchange rate risks are perfectly correlated, a risk- averse firm, by using financial hedging, will achieve the same optimal utility as a risk-neutral firm. In this paper as well, a special case is examined regarding two suppliers in China and Vietnam. The results show that if a single supplier is contracted, financial hedging most benefits the highly risk-averse firm when the demand and exchange rate are highly negatively related. When only one hedge is used, financial hedging dominates operational hedging only when the firm is very risk averse and the correlation between the two exchange rates have become positive. With both theoretical and numerical results, this paper concludes that the two hedges are strategic tools and interact each other to maximize the optimal utility
âSandwich generationâ in China: a mixed method approach for the effects of work-related psychosocial factors on occupational stress among Chinese post-eighties
This dissertation employed a mixed method approach to examine the relationships between work-related psychosocial factors and occupational stress and explore the roles of personal and social values in stress process. In quantitative strand of this dissertation, the Copenhagen Psychosocial Questionnaire succeeded to identify possible influence of occupational psychosocial factors on employeesâ self-rated health and perceived stress among Chinese post-eighties. The results show that Chinese post-eighties health conditions are positively associated with Satisfaction with work and Trust, while negatively associated with Burnout and Justice and respect. Moreover, Chinese post-eighties perceived stress is positively associated with WFC and negatively associated with Satisfaction with work. In qualitative strand of the present study, the findings answered the research concern on the role of personal and social values in the process of stress among Chinese post-eighties. The individuals and their surrounding social settings are seen as two parties competing for value creating resources, in which process stress is associated with the potential incompatibilities between them. After the categorization of information and the identification of themes, a theoretical model was built to organize the relationship between qualitative constructs. This model takes a two dimensional form which contains axis of Self-Rigidity and System Rigidity. The relevant coping behaviors are associated with different combinations of these two dimensions
Author Correction: Solution-processed hybrid perovskite photodetectors with high detectivity.
This Article contains an error in Equation 2 in that the denominator is inverted. This has not been fixed in the PDF or HTML versions of the Article but can be seen in the associated Correction
Penalty-Based Imitation Learning With Cross Semantics Generation Sensor Fusion for Autonomous Driving
In recent times, there has been a growing focus on end-to-end autonomous
driving technologies. This technology involves the replacement of the entire
driving pipeline with a single neural network, which has a simpler structure
and faster inference time. However, while this approach reduces the number of
components in the driving pipeline, it also presents challenges related to
interpretability and safety. For instance, the trained policy may not always
comply with traffic rules, and it is difficult to determine the reason for such
misbehavior due to the lack of intermediate outputs. Additionally, the
successful implementation of autonomous driving technology heavily depends on
the reliable and expedient processing of sensory data to accurately perceive
the surrounding environment. In this paper, we provide penalty-based imitation
learning approach combined with cross semantics generation sensor fusion
technologies (P-CSG) to efficiently integrate multiple modalities of
information and enable the autonomous agent to effectively adhere to traffic
regulations. Our model undergoes evaluation within the Town 05 Long benchmark,
where we observe a remarkable increase in the driving score by more than 12%
when compared to the state-of-the-art (SOTA) model, InterFuser. Notably, our
model achieves this performance enhancement while achieving a 7-fold increase
in inference speed and reducing the model size by approximately 30%. For more
detailed information, including code-based resources, they can be found at
https://hk-zh.github.io/p-csg
Quantum Dueling: an Efficient Solution for Combinatorial Optimization
In this paper, we present a new algorithm for generic combinatorial
optimization, which we term quantum dueling. Traditionally, potential solutions
to the given optimization problems were encoded in a ``register'' of qubits.
Various techniques are used to increase the probability of finding the best
solution upon measurement. Quantum dueling innovates by integrating an
additional qubit register, effectively creating a ``dueling'' scenario where
two sets of solutions compete. This dual-register setup allows for a dynamic
amplification process: in each iteration, one register is designated as the
'opponent', against which the other register's more favorable solutions are
enhanced through a controlled quantum search. This iterative process gradually
steers the quantum state within both registers toward the optimal solution.
With a quantitative contraction for the evolution of the state vector,
classical simulation under a broad range of scenarios and hyper-parameter
selection schemes shows that a quadratic speedup is achieved, which is further
tested in more real-world situations. In addition, quantum dueling can be
generalized to incorporate arbitrary quantum search techniques and as a quantum
subroutine within a higher-level algorithm. Our work demonstrates that
increasing the number of qubits allows the development of previously
unthought-of algorithms, paving the way for advancement of efficient quantum
algorithm design.Comment: 18 pages, 10 figure
Solution-processed small-molecule solar cells: breaking the 10% power conversion efficiency.
A two-dimensional conjugated small molecule (SMPV1) was designed and synthesized for high performance solution-processed organic solar cells. This study explores the photovoltaic properties of this molecule as a donor, with a fullerene derivative as an acceptor, using solution processing in single junction and double junction tandem solar cells. The single junction solar cells based on SMPV1 exhibited a certified power conversion efficiency of 8.02% under AM 1.5 G irradiation (100 mW cm(-2)). A homo-tandem solar cell based on SMPV1 was constructed with a novel interlayer (or tunnel junction) consisting of bilayer conjugated polyelectrolyte, demonstrating an unprecedented PCE of 10.1%. These results strongly suggest solution-processed small molecular materials are excellent candidates for organic solar cells
Microstructural evolution of boron nitride particles in advanced 9Cr power plant steels
B and N can be used to increase the creep strength of advanced 9Cr power plant steels by means of microstructural stabilization and precipitation strengthening; however, the formation of boron nitride (BN) particles removes B and N from solution and reduces the strengthening effect of B and N simultaneously. In the current study, the BN precipitation/dissolution conditions in 9Cr-3W-3Co-V-Nb steels have been investigated to understand how to prevent the formation of BN. A series of austenitizing heat treatments have been designed using thermodynamic predictions as a guide in an attempt to dissolve the BN present after the production of 9Cr-3W-3Co-V-Nb type steels and to prevent also the precipitation of BN during the subsequent heat treatments. Advanced electron microscopy has been carried out to investigate the evolution of the BN particles in relation to the austenitization temperature. Energy Dispersive X-ray spectroscopy (EDS) has been used to identify the B-containing phases, and a method has been developed using secondary electron images to quantify the amount of BN present within the microstructure. It has been found that BN solubility is sensitive to the B and N levels in the steel composition, as indicated by thermodynamic calculations. However, it is proposed that austenitizing heat treatments at temperatures ranging from 1448 K to 1473 K (from 1175 °C to 1200 °C) with durations from 1 to 7 hours can effectively prevent the precipitation of BN as well as dissolving most of the BN particles formed during initial steel manufacture
Scaling Behavior of Entanglement in Two- and Three-Dimensional Free Fermions
Exactly solving a spinless fermionic system in two and three dimensions, we
investigate the scaling behavior of the block entropy in critical and
non-critical phases. The scaling of the block entropy crucially depends on the
nature of the excitation spectrum of the system and on the topology of the
Fermi surface. Noticeably, in the critical phases the scaling violates the area
law and acquires a logarithmic correction \emph{only} when a well defined Fermi
surface exists in the system. When the area law is violated, we accurately
verify a conjecture for the prefactor of the logarithmic correction, proposed
by D. Gioev and I. Klich [quant-ph/0504151].Comment: 4 pages, 4 figure
A polymer tandem solar cell with 10.6% power conversion efficiency.
An effective way to improve polymer solar cell efficiency is to use a tandem structure, as a broader part of the spectrum of solar radiation is used and the thermalization loss of photon energy is minimized. In the past, the lack of high-performance low-bandgap polymers was the major limiting factor for achieving high-performance tandem solar cell. Here we report the development of a high-performance low bandgap polymer (bandgap <1.4 eV), poly[2,7-(5,5-bis-(3,7-dimethyloctyl)-5H-dithieno[3,2-b:2',3'-d]pyran)-alt-4,7-(5,6-difluoro-2,1,3-benzothia diazole)] with a bandgap of 1.38 eV, high mobility, deep highest occupied molecular orbital. As a result, a single-junction device shows high external quantum efficiency of >60% and spectral response that extends to 900 nm, with a power conversion efficiency of 7.9%. The polymer enables a solution processed tandem solar cell with certified 10.6% power conversion efficiency under standard reporting conditions (25 °C, 1,000 Wm(-2), IEC 60904-3 global), which is the first certified polymer solar cell efficiency over 10%
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