Origin-destination (OD) flow modeling is an extensively researched subject across multiple disciplines, such as the investigation of travel demand in transportation and spatial interaction modeling in geography. However, researchers from different fields tend to employ their own unique research paradigms and lack interdisciplinary communication, preventing the cross-fertilization of knowledge and the development of novel solutions to challenges. This article presents a systematic interdisciplinary survey that comprehensively and holistically scrutinizes OD flows from utilizing fundamental theory to studying the mechanism of population mobility and solving practical problems with engineering techniques, such as computational models. Specifically, regional economics, urban geography, and sociophysics are adept at employing theoretical research methods to explore the underlying mechanisms of OD flows. They have developed three influential theoretical models: the gravity model, the intervening opportunities model, and the radiation model. These models specifically focus on examining the fundamental influences of distance, opportunities, and population on OD flows, respectively. In the meantime, fields such as transportation, urban planning, and computer science primarily focus on addressing four practical problems: OD prediction, OD construction, OD estimation, and OD forecasting. Advanced computational models, such as deep learning models, have gradually been introduced to address these problems more effectively. We have constructed the benchmarks for these four problems at https://github.com/tsinghua-fib-lab/OD_benckmark. Finally, based on the existing research, this survey summarizes current challenges and outlines future directions for this topic. Through this survey, we aim to break down the barriers between disciplines in OD flow related research, fostering interdisciplinary perspectives and modes of thinking.

• Book : 57(1)
• Pub. Date : 2025
• Page : pp.1-49
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• Book : 56(1)
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• Book : 56(1)
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Abstract

A detailed research study was performed on the annual energy received by a fixed-tilt solar collector. A new clear-sky model of solar radiation was developed by combining existing clear-sky models with a unique algorithm. This model was then used to perform tilt angle optimizations with two different objectives. The first objective is to achieve the maximum annual solar energy received by a solar panel, while the second is to balance the energy received so that it is more uniform over the course of a year. Each of these objectives has differing optimum tilt values, depending on the location and usage of a solar collectorsystem. The novelty of this investigation is the use of the aforementioned solar model for multiple optimizations for these two different objectives, which results in two different optimum tilt angles that are in turn different from the widely accepted rule-of-thumb that recommends an angle that is equal to the latitude. The solar radiation results obtained with the model used herein were experimentally confirmed through comparison with measured weather data for a number of locations with different sky-clearness indexes as well as compared with other studies found in the literature. A major contribution of this study is the plots and tables showing optimum tilt angles as estimated by the model as well as with empirical data. By selecting the appropriate tilt angle, a designer can now decide to either maximize annual energy received or else balance energy delivery over the year.

• Book : 147(2)
• Pub. Date : 2025
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• Book : 242(1)
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Abstract

C4F7N-CO2-O2 is currently considered the most promising replacement for SF6 in high-voltage circuit breakers. During high-current interruption conditions, arc radiation plays a pivotal role in arc modeling and is frequently accompanied by vapors ablated from the electrodes and nozzles. To investigate the influence of ablated vapors on the radiative properties of gas mixtures, net emission coefficients (NECs) for various ratios of C4F7N mixtures and PTFE and Cu vapors are calculated under the assumption of local thermodynamic equilibrium. The NECs for [C4F7N-CO2-O2]-PTFE-Cu mixtures that are obtained are required for radiation modeling and arc simulation in high-voltage circuit breakers. It has been found that neglecting the presence of PTFE vapor does not affect the NEC at high temperatures. However, the influence of copper vapor on the radiative properties in the high-temperature region becomes apparent at elevated ratios, and self-absorption is more pronounced at very high pressures. Based on these findings, recommendations for choosing NECs for use in modeling that balance accuracy and efficiency are proposed.

• Book : 58(1)
• Pub. Date : 2025
• Page : pp.015206
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• Book : 255()
• Pub. Date : 2025
• Page : pp.116354
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