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Video
We introduce a Dimension-Reduced Second-Order Method (DRSOM) for convex and nonconvex (unconstrained) optimization. Under a trust-region-like framework, our method preserves the convergence of the second-order method while using only Hessian-vector products in two directions. Moreover; the computational overhead remains comparable to the first-order such as the gradient descent method. We show that the method has a local super-linear convergence and a global convergence rate of 0(∈-3/2) to satisfy the first-order and second-order conditions under a commonly used approximated Hessian assumption. We further show that this assumption can be removed if we perform one step of the Krylov subspace method at the end of the algorithm, which makes DRSOM the first first-order-type algorithm to achieve this complexity bound. The applicability and performance of DRSOM are exhibited by various computational experiments in logistic regression, L2-Lp minimization, sensor network localization, neural network training, and policy optimization in reinforcement learning. For neural networks, our preliminary implementation seems to gain computational advantages in terms of training accuracy and iteration complexity over state-of-the-art first-order methods including SGD and ADAM. For policy optimization, our experiments show that DRSOM compares favorably with popular policy gradient methods in terms of the effectiveness and robustness.
Event date: 19/09/2022
Speaker: Prof. Yinyu Ye (Stanford University)
Hosted by: Department of Applied Mathematics
- Subjects:
- Mathematics and Statistics
- Keywords:
- Convex programming Nonconvex programming Mathematical optimization
- Resource Type:
- Video
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Video
In this video, it covers the topic of (1).2D layered transition metal dichalcogenides; (2) Theoretical study on opto-electronic properties of 2D materials; and (3) Molecularly thin 2D quantum ruddlesden-popper perovskites.FAST is organizing the Research at FAST Seminar Series 2021/22 in the coming months to explore collaboration opportunities within PolyU community. The series also serve as a platform for colleagues to get to know FAST researchers.
- Subjects:
- Electronic Engineering and Materials Science
- Keywords:
- Two-dimensional materials Quantum chemistry
- Resource Type:
- Video
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Video
An online lecture on the topic of "What is Microgravity? Discovering Interesting Phenomena in Microgravity".This lecture of “Science World: Exploring Space to Benefit Mankind” Education Programme in the 2021/22 school year for secondary students, which aims to cultivate the interest of local youth in space science and elevate their enthusiasm for participating in the development of space technology.
- Subjects:
- Physics and Aeronautical and Aviation Engineering
- Keywords:
- Gravity Reduced gravity environments
- Resource Type:
- Video
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Video
Synthetic biology can be used in industrial biotechnology to engineer metabolic pathways to create high-value chemicals using model microorganisms such as yeast. During the Synthetic Biology in Action course, participants engineered yeast to produce beta-caretone for industrial biotechnology purposes. In this talk, they describe the steps they took to engineer an existing yeast pathway to produce the new chemical. These steps include modeling the metabolic pathway outputs, DNA design, amplification, and assembly, and analysis of the final result.
- Subjects:
- Electronic and Information Engineering, Biochemistry, and Biology
- Keywords:
- Synthetic biology Biochemistry Yeast fungi -- Biotechnology
- Resource Type:
- Video
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Video
Inventor, entrepreneur and visionary Ray Kurzweil explains in abundant, grounded detail why, by the 2020s, we will have reverse-engineered the human brain and nanobots will be operating your consciousness.
- Subjects:
- Technology
- Keywords:
- Technological innovations Bioengineering Information Technology
- Resource Type:
- Video
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Video
In this wide-ranging, thought-provoking talk, Kevin Kelly muses on what technology means in our lives -- from its impact at the personal level to its place in the cosmos.
- Subjects:
- Technology
- Keywords:
- Technology -- Social aspects Technological innovations -- Social aspects
- Resource Type:
- Video
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Video
In our tech-driven, interconnected world, we've developed new ways and rules to court each other, but the fundamental principles of love have stayed the same, says anthropologist Helen Fisher. Our faster connections, she suggests, are actually leading to slower, more intimate relationships. At 12:20, couples therapist and relationship expert Esther Perel steps in to make an important point -- that while love itself stays the same, technology has affected the way we form and end relationships.
- Subjects:
- Anthropology, Sociology, and Technology
- Keywords:
- Love Courtship Communication technology Interpersonal communication
- Resource Type:
- Video
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Video
Nearly every other year the transistors that power silicon computer chip shrink in size by half and double in performance, enabling our devices to become more mobile and accessible. But what happens when these components can't get any smaller? George Tulevski researches the unseen and untapped world of nanomaterials. His current work: developing chemical processes to compel billions of carbon nanotubes to assemble themselves into the patterns needed to build circuits, much the same way natural organisms build intricate, diverse and elegant structures. Could they hold the secret to the next generation of computing?
- Subjects:
- Nanotechnology and Electric and information Engineering
- Keywords:
- Nanoelectromechanical systems Nanotechnology
- Resource Type:
- Video
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Video
"We've been promised a future of chrome -- but what if the future is fleshy?" asks biological designer Christina Agapakis. In this awe-inspiring talk, Agapakis details her work in synthetic biology -- a multidisciplinary area of research that pokes holes in the line between what's natural and artificial -- and shares how breaking down the boundaries between science, society, nature and technology can lead us to imagine different possible futures.
- Subjects:
- Technology and Biology
- Keywords:
- Synthetic biology Sci9ence -- Social aspects
- Resource Type:
- Video
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Video
TED Fellow Lucy McRae is a body architect -- she imagines ways to merge biology and technology in our own bodies. In this visually stunning talk, she shows her work, from clothes that recreate the body's insides for a music video with pop-star Robyn, to a pill that, when swallowed, lets you sweat perfume.
- Subjects:
- Biomedical engineering and Biology
- Keywords:
- Synthetic biology Bioengineering
- Resource Type:
- Video