18,933 research outputs found
Neural-embedded discrete choice models
No full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2019Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 131-139).This dissertation is motivated by the possible value of integrating theory-based discrete choice models (DCM) and data-driven neural networks. How to benefit from the strengths of both is the overarching question. I propose hybrid structures and strategies to flexibly represent taste heterogeneity, reduce potential biases, and improve predictability while keeping model interpretability. Also, I utilize neural networks' training machinery to speed up and scale up the estimation of Latent Class Choice Models (LCCMs). First, I embed neural networks in DCMs to enable flexible representations of taste heterogeneity and enhance prediction accuracy. I propose two neural-embedded choice models: TasteNet-MNL and nonlinear-LCCM. Both models provide a flexible specification of taste as a function of individual characteristics. TasteNet-MNL extends the Multinomial Logit Model (MNL).A feed-forward neural network (TasteNet) is utilized to predict taste parameters as a nonlinear function of individual characteristics. Taste parameters generated by TasteNet are further fed into a parametric logit model to formulate choice probabilities. I demonstrate the effectiveness of this integrated model in capturing nonlinearity in tastes without a priori knowledge. Using synthetic data, TasteNet-MNL is able to recover the underlying utility specification and predict more accurately than some misspecified MNLs and continuous mixed logit models. TasteNet-MNL also provides interpretations close to the ground truth. In an application to a public dataset (Swissmetro), TasteNet-MNL achieves the best out-of-sample prediction accuracy and discovers a broader spectrum of taste variation than the benchmark MNLs with linear utility specifications. Nonlinear-LCCM enriches the class membership model of a typical LCCM.I represent an LCCM by a neural network and add hidden layers with nonlinear transformations to its class membership model. The nonlinearity introduced by the neural network provides a flexible approximation of the mixing distribution for both systematic and random taste heterogeneity. I apply this method to model Swissmetro mode choice. The nonlinear-LCCM outperforms an LCCM with a linear class membership model with respect to the out-of-sample prediction accuracy. Nonlinear-LCCM also provides interpretable taste parameters for each latent class.by Yafei Han.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Civil and Environmental Engineerin
Dataset to support the article "High-resolution 𝜙-OFDR using phase unwrap and nonlinearity suppression"
No full textThis dataset is used for realizing high resolution of phase-sensitive Optical Frequency Domain Reflectometer. It is associated with the research paper:
Guo Z, Yan J, Han G, Yu Y, Greenwood D and Marco J (2023) "High-Resolution φ-OFDR Using Phase Unwrap and Nonlinearity Suppression". Journal of Lightwave Technology, 41 (9), 2885-2891. (https://doi.org/10.1109/JLT.2023.3236775).
The data is presented as an excel file:
High_resolution_OFDR_using_phase_unwrap_and_nonlinearity_suppression.xlsx
This work was funded by High Value Manufacturing Catapult and the Engineer and Physical Sciences Research Council - EPSRC EP/V000624/1. The author Gaoce Han would like to acknowledge the China Scholarship Council for sponsoring.</span
Temporal transferability assessments of vehicle ownership models and trip generation models for Boston Metropolitan Area
No full textThesis: M.C.P., Massachusetts Institute of Technology, Department of Urban Studies and Planning, 2015.Thesis: S.M. in Transportation, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (pages 158-162).In the last few decades, travel demand models have undergone tremendous development and, today, are routinely used to support planning and policy decisions. But uncertainty in forecasting with such models is often overlooked, and its impact on forecast accuracy is rarely evaluated. My thesis is motivated to understand behavior uncertainty and model uncertainty in travel demand modeling. In particular, I assess the temporal transferability of vehicle ownership models and trip generation models for Boston metropolitan area from 1990 to 2010. Through statistical tests, I find significantly changed preferences in household vehicle ownership choice and trip production. For vehicle ownership choice, the effects of most socio-economic and demographic factors, and regional location factor have evolved; while the effects of local built environment factors and transit access are stable. Trip rates have changed over time, with decreased home-based work, home-based shopping, home-based bank and personal business, home-based social, home-based eating and non-home-based work trips; and increased home-based recreational and home-based work-related trips. The prediction tests suggest that failing to consider preference changes cause significant bias in forecasts. The transferred vehicle ownership model of 1991 under-predicts 0- vehicle households by 42.5%, and over-predicts 2-vehicle households by 14.8% in 2010. The transferred trip rates from 1991 overestimate total trips in 2010 by 7% to 9%. Homebased work-related, home-based pick-up and drop-off, and home-based recreational trips are significantly unpredicted by 34%, 12% and 27%; while home-based work, home-based shopping, home-based social, and non-home-based work trips are significantly overpredicted by 9%, 20%, 31%, and 69%. Different model specifications have shown a modest range of variability in prediction outcomes, suggesting model specification uncertainty has less influence on forecasts than behavior uncertainty. In vehicle ownership modeling, children, seniors, and local built environment variables improve the prediction accuracy for 0-vehicle group. But all model specifications cannot well distinguish between 0- and 1-vehicle households, and between 2- and 3-vehicle households. Household characterization affects the prediction accuracy for certain trip purposes. Including more detailed household information may lead to worse forecasts because of large sampling variance. Future works are suggested to incorporate behavior uncertainty in forecast, explore uncertainty in model structure, and evaluate the practical implications of the lack of model transferability.by Yafei Han.M.C.P.S.M. in Transportatio
Han Suyin (Chinese author) speaking at Dallas Brookes Hall.
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/276390Han Suyin (Chinese author) speaking at Dallas Brookes Hall.200056
Item: [1999.0081.00439] "Han Suyin (Chinese author) speaking at Dallas Brookes Hall.
A Study on the mathematics textbooks in the era of the Great Han Empire
No full text이 글은 갑오경장(1894)과 경술 국치(1910) 사이에 간행된 산학(수학) 교재류의 목록을 확인하고, 각 텍스트의 출판과 관련된 사항, 소장처, 이본 등의 서지적 정보와 함께 이 시기 산학 교재류의 국어사 자료로서의 의의를 언어 사용 상의 측면에 초점을 두어 정리하는 것을 목적으로 한다. 이는 현대 한국어 태동기의 분과 학문의 도입 양상에 대한 연구의 일환인 한편, 학술 용어의 번역과 정착을 중심으로 이 시기의 한국어의 어휘 확장 양상을 확인하는 데에 필요한 기초 자료를 정리하는 작업의 한 부분이다. 본 연구에 앞선 산학(수학) 교재류에 대한 연구로는 산학 교재류의 서지 사항에 대해 기술한 강윤호(1973:187-199), 김봉희(1992:247-253), 한길준(2009), 오채환 외(2010) 등이 있고, 한국 수학사를 기술하면서 교재류를 함께 다룬 것으로 김용운·김용국(1982)와 이상구(2013)이 있다.This paper aims to make a whole list of the mathematics textbooks in the era of the Great Han Empire and summerize bibliographical data and linguistic characteristics in view of Korean history. In chapter 1, the author reviewed former studies which deals with the mathematics textbooks in the era of the Great Han Empire. In chapter 2, the author summerized bibliographical data of 45 volumes of 32 kinds textbooks. In chapter 3, the author described linguistic characteristics of the textbooks, especially focusing on writing systems, the use of Arabic numerals, horizontal writing, and presence of index or glossary
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
Dataset to support the article "High Sensing Accuracy Realisation with Millimetre/sub-Millimetre Resolution in Optical Frequency Domain Reflectometer"
No full textThis dataset is used for realizing high sensing accuracy and sub-millimetre resolution of Optical Frequency Domain Reflectometer. It is associated with the research paper "High Sensing Accuracy Realisation with Millimetre sub-Millimetre Resolution in Optical Frequency Domain Reflectometer" in Journal: Journal of Lightwave Technology.
This work was funded by High Value Manufacturing Catapult, grant reference, 160080 CORE (WMG), titled ‘Smart Sensing for Future Batteries’ and the EPSRC (Engineering and Physical Sciences Research Council), grant reference EP/R004927/1, titled ‘Prosperity Partnership’. The author Gaoce Han would like to acknowledge the China Scholarship Council for sponsoring.</span
When the Tides Come, Where Will We Go?
No full textFor coastal urban areas, an increase in flooding is one of the clearest climate change threats. The research presented in this paper demonstrates how a land use-transport model can be used to forecast the short-and longer-Term impacts of a potential 4-ft sea level rise in greater Boston, Massachusetts, by 2030. The short-Term scenario represents the immediate transport system response to inundation, which provides a measure of resiliency in the case of an extreme event, such as a storm surge. In the short run, the results reveal that transit captive users will suffer more. Transit, in general, displays less resiliency, at least in part because of the center city's vulnerability and Boston's radial transit system. Trip distances would modestly decrease, and average travel speeds would go down by more than 50%. Rail transit ridership would be decimated, and overall transit usage would go down by 66%. The longer-Term scenario predicts how households and firms would prefer to relocate in the so-called new equilibrium when more than 10 mi2 of land disappears and the transport network inundations become permanent. Assuming no supply constraints, new residential growth centers would emerge on the peripheries of the inundated zones, primarily in the inner-core suburbs. Some regional urban centers and traditional industrial towns would boom. Firms would be hit harder, because of their heavy concentration in the inner core; firm relocation would largely follow households. Transit usage would again be decimated, but walking trips would increase. Results, however, should be viewed as cautious speculation
supplementary_materials_(4) - Correlation Between Uptake of <sup>18</sup>F-FDG During PET/CT and Ki-67 Expression in Patients Newly Diagnosed With Multiple Myeloma Having Extramedullary Involvement
No full textsupplementary_materials_(4) for Correlation Between Uptake of 18F-FDG During PET/CT and Ki-67 Expression in Patients Newly Diagnosed With Multiple Myeloma Having Extramedullary Involvement by Qian Li, Jing Ma, Han Li, Wengui Xu, Zeng Cao, Su Liu, Lin Chen, Shuang Gao, Tinghui Yan, Dongying Li, Xue Wang, Yuanfang Yue, Zhigang Zhao, Xiaofang Wang, Hongliang Yang, Haifeng Zhao, Yong Yu, Yizhuo Zhang, Feiyue Fan and Yafei Wang in Technology in Cancer Research & Treatment</p
Corvèe under Han
No full textThe author distinguishes between the corvee systems of Ch'in and Han. In spite of the fact that the corvee system underwent a marked change in 167 B. C. in the reign of Emperor Wen of Former Han, the fact has been hitherto almost entirely overlooked. The author tries to reconstruct the Ch'in corvee system from various sources. In the sense that these two ancient empires were despotic in their constitution there was no essential difference between their system of government, but Han succeeded in melting feudalistic residues of the Chan-kuo period into her own system, while Ch'in failed in doing so due to the short period of her rule. Moreover, Ch'in failed in taking local differences into consideration in establishing her institutions. In the author's view the reign of Emperor Wen is significant in the sense that it represents renovation of the feudalistic taxation system and of the uniform and artificial system of local administration
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