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Video
In this lecture I consider the fundamental, challenging and largely unsolved problem of deriving rigorously the most popular kinetic equations, starting from the laws governing the dynamics of microscopic systems. I plan to present classical and recent results, discussing also some present perspectives.
Event date: 30/3/2023
Speaker: Prof. Mario Pulvirenti (University of Roma La Sapienza)
Hosted by: Department of Applied Mathematics
- Subjects:
- Mathematics and Statistics
- Keywords:
- Mathematical models Kinetic theory of gases -- Mathematical models
- Resource Type:
- Video
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Video
We investigate reversal and recirculation for the stationary Prandtl equations. Reversal describes the solution after the Goldstein singularity, and is characterized by regions in which u > O and u < 0. The classical point of view of regarding the Prandtl equations as an evolution equation in x completely breaks down since u changes sign. Instead, we view the problem as a quasilinear, mixed-type, free-boundary problem. This is a joint work with Sameer Iyer.
Event date: 14/3/2023
Speaker: Prof. Nader Masmoudi (New York University)
Hosted by: Department of Applied Mathematics
- Subjects:
- Mathematics and Statistics
- Keywords:
- Fluid dynamics -- Mathematical models
- Resource Type:
- Video
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Video
In the context of hyperbolic systems of balance laws with dissipative source manifesting relaxation, recent pr"Ogress will be reported in the program of passing to the limit, in 1he BV setting, as the relaxation lime tends to zero.
Event date: 16/2/2023
Speaker: Prof. Constantine Dafermos (Brown University)
Hosted by: Department of Applied Mathematics
- Subjects:
- Mathematics and Statistics
- Keywords:
- Equilibrium -- Mathematical models Relaxation Differential equations Hyperbolic
- Resource Type:
- Video
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Video
Models arising in biology are often written in terms of Ordinary Differential Equations. The celebrated paper of Kermack-McKendrick (19271, founding mathematical epidemiology, showed the necessity to include parameters in order to describe the state of the individuals, as time elapsed after infection. During the 70s, many mathematical studies were developed when equations are structured by age, size, more generally a physiological trait. The renewal, growth-fragmentation are the more standard equations. The talk will present structured equations, show that a universal generalized relative entropy structure is available in the linear case, which imposes relaxation to a steady state under non-degeneracy conditions. In the nonlinear cases, it might be that periodic solutions occur, which can be interpreted in biological terms, e.g., as network activity in the neuroscience. When the equations are conservation laws, a variant of the Monge-Kantorovich distance (called Fortet-Mourier distance) also gives a general non-expansion property of solutions.
Event date: 19/1/2023
Speaker: Prof. Benoît Perthame (Sorbonne University)
Hosted by: Department of Applied Mathematics
- Subjects:
- Biology and Mathematics and Statistics
- Keywords:
- Biomathematics Equations
- Resource Type:
- Video
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Video
Universities conduct research for three reasons: to educate students, to contribute to society, and to understand the world. While society often holds a view of the scholar as a solitary and singular genius, in reality scholars today participate in a highly collaborative, worldwide search for shared understandings that stand the test of time and the scrutiny of others. The problems in the 21st century often demand effort by teams of researchers with resources at scale: laboratories and equipment, compute resources, and expert staffing. Working with faculty, students, and other stakeholders to identify the greatest opportunities and the resources needed to address them is both a privilege and a challenge for modern academic administrators. In this talk, I will share three examples: fostering collaborative proposal-writing; planning for shared capabilities in experimental facilities, data, and computation; and transforming academic structures.
Even date: 12/4/2023
Speaker: Prof. Kathryn Ann Moler
Hosted by: PolyU Academy for Interdisciplinary Research
- Subjects:
- Statistics and Research Methods
- Keywords:
- Research Science
- Resource Type:
- Video
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Video
In this CIHK webinar, we will discuss the material conditions of and historical background to the use of Classical Chinese or Literary Sinitic in writing-mediated brush conversation between literati of Sinitic engaged in cross-border communication within Sinographic East Asia or the Sinographic cosmopolis, which corresponds with today’s China, North Korea, South Korea, Japan (including Okinawa, formerly the Ryukyu Kingdom) and Vietnam. Compared with speech as a modality of communication, real-time writing-mediated interaction between talking humans, synchronously face-to-face, seems uncommon. In any society, speaking is premised on one condition: the interlocutors must have at least one shared spoken language at their disposal, but even then, there are circumstances under which speaking is either physically not feasible or socially inappropriate. Could writing function as an alternative modality of communication when speaking is not an option due to the absence of a shared spoken language, as in cross-border communication settings? Whereas real-time writing-mediated face-to-face interaction is rare where a regional lingua franca was known to exist (e.g., Latin and Arabic), there is ample historical evidence of literati of Classical Chinese or Literary Sinitic from different parts of Sinographic East Asia conducting ‘silent conversation’, synchronously and interactively in writing mode using brush, ink, and paper. Such a pattern of writing-assisted interaction is still practiced and observable in pen-assisted conversation – pen-talk – between Chinese and Japanese speakers today, thanks to the pragma-linguistic affordance of morphographic, non-phonographic sinograms (i.e., Chinese characters and Japanese kanji). We will outline the historical spread of Classical Chinese or Sinitic texts from the ‘center’ to the ‘peripheries’, and the historical background to the acquisition of literacy in Sinitic by the people there. Their shared knowledge of Sinitic helps explain why, for well over a thousand years until the 1900s, literati from these places were able to speak their mind by engaging in ‘Sinitic brush-talk’ 漢文筆談 in cross-border communication.
Even date: 13/5/2022
Speaker: Prof. David C. S. Li
Hosted by: Confucius Institute of Hong Kong, Department of Chinese Culture
- Subjects:
- Chinese Language and Language and Languages
- Keywords:
- Chinese characters History Chinese language -- Written Chinese Written communication China East Asia
- Resource Type:
- Video
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Video
Focusing on tensions and links between national formation and international outlooks, this talk shows how classical world visions persist as China’s modernizers and revolutionaries adopted and revised the Western nation-state and cosmopolitanism. The concepts of tianxia (all under heaven) and datong (great harmony) have been updated into outlooks of global harmony that value unity, equality, and reciprocity as strategies of overcoming interstate conflict, national divides, and social fragmentation. The talk will delve into two debates: the embrace of the West vs. aspirations for a common world, and the difference between liberal cosmopolitanism and socialist internationalism.
Even date: 16/9/2022
Speaker: Prof. Ban Wang
Hosted by: Confucius Institute of Hong Kong, Department of Chinese Culture
- Subjects:
- Chinese Studies
- Keywords:
- Civilization Diplomatic relations World politics China
- Resource Type:
- Video
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Video
More than one hundred years ago, Albert Einstein published his Theory of General Relativity (GR). One year later, Karl Schwarzschild solved the GR equations for a non-rotating, spherical mass distribution; if this mass is sufficiently compact, even light cannot escape from within the so-called event horizon, and there is a mass singularity at the center. The theoretical concept of a 'black hole' was born, and was refined in the next decades by work of Penrose, Wheeler, Kerr, Hawking and many others. First indirect evidence for the existence of such black holes in our Universe came from observations of compact X-ray binaries and distant luminous quasars. I will discuss the forty-year journey, which my colleagues and I have been undertaking to study the mass distribution in the Center of our Milky Way from ever more precise, long-term studies of the motions of gas and stars as test particles of the space time. These studies show the existence of a four million solar mass object, which must be a single massive black hole, beyond any reasonable doubt.
Even date: 9/2/2023
Speaker: Prof. Reinhard GENZEL
Hosted by: PolyU Academy for Interdisciplinary Research
- Subjects:
- Physics and Cosmology and Astronomy
- Keywords:
- Nobel Prize winners Astrophysics Astronomy Deep space -- Milky Way Black holes (Astronomy) General relativity (Physics)
- Resource Type:
- Video
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Video
As a recent New York Times editorial proclaimed, "The Global Order Isn't Working. It's Time for Something Different." To teach environmental history and environmental ethics is to reacquaint ourselves with the facts that we need to try to build, while there is still time, a new cooperative order that understands this: simple fact: that other people and other countries are quite literally "the air we breathe." Moreover, all who claim to be ethical persons must take seriously the notion of inter-generational equity and try to act upon it. This notion should, in theory, come more easily to countries whose traditions have built upon classical/ Confucian learning, for those traditions say that the most important marker of human behavior is working toward common ends (qun 群) while "learning what is enough" (zhi zu 知足). Put another way, many resources within the Chinese tradition may strengthen our resolve to act more constructively in less short-sighted ways.
Event Date: 14/11/2022
Speaker: Prof. Michael Nylan (University of California, Berkeley)
Hosted by: Faculty of Humanities
- Keywords:
- Confucian ethics Intergenerational relations Environmental ethics Philosophy Confucian
- Resource Type:
- Video
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Video
The notion of expertise is integral to all forms of institutional and professional practice in many domains – in education, healthcare, social welfare, law, journalism, banking, information technology, marketing, translating and interpreting services etc. It is a concept addressed by scholars across many disciplines – cognitive science, sociology, anthropology, psychology, language/communication studies, among others. There are, however, enduring problems of definition, description and measurement of expertise. Some scholars draw attention to the ongoing ‘crisis in expertise’ and others pronounce the ‘death of expertise’ in contemporary society.
More humbly, I begin with a characterisation of professional expertise very broadly to include scientific, experiential, technological, organisational, legal, ethical and communicative knowledge. This then leads me to the notion of ‘distributed expertise’, which extends beyond the individual remit and the conventional lay-expert divide. For instance, in the healthcare domain, a significant development afforded by internet-based technology is the increased level of patients’ e-health literacy and, consequently, democratisation of expertise. This amounts not only to accessing health information digitally, but also the phenomenon of patients ‘doctoring’ themselves in ‘the now of its presence’, i.e., ‘expert patients’ becoming instrumental in self-diagnosis and even self-treatment.
Additionally, ‘distributed expertise’ is also constitutive of ‘expert systems’, e.g., diagnostic and interventionist technologies as well as decision aids mediated by algorithms and templates. This is what I refer to as the technologization of expertise. I suggest that there is overreliance on ‘expert systems’ by both experts and lay persons in everyday decision making. Access to and use of ‘expert systems’ in optimal ways inevitably necessitates a reconfiguration of the very conditions and consequences of professional expertise.
Event Date: 25/11/2022
Speaker: Prof. Srikant Sarangi (Hong Kong Polytechnic University)
Hosted by: Faculty of Humanities
- Keywords:
- Expertise Democratization Information technology -- Social aspects
- Resource Type:
- Video
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Video
Professor Yigong Shi will reflect on the challenges in global higher education, based on his 37 years of learning, scientific research, and teaching experience in academia. He will present Westlake University's educational reforms in university operations, governance, talent recruitment, student development, research and academic evaluation, and interdisciplinary studies, which altogether provide new opportunities for future-oriented higher education.
Even date: 6/12/2022
Speaker: Prof. Yigong Shi
Moderator: Prof. Qingyan Chen (Hong Kong Polytechnic University)
Hosted by: PolyU Academy for Interdisciplinary Research
- Keywords:
- Educational change China Education Higher
- Resource Type:
- Video
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Video
Before the advent of computers around 1950, optimization centered either on small-dimensional problems solved by looking at zeroes of first derivatives and signs of second derivatives, or on infinite-dimensional problems about curves and surfaces. In both cases, "variations" were employed to understand how a local solution might be characterized. Computers changed the picture by opening the possibility of solving large-scale problems involving inequalities, instead of only equations. Inequalities had to be recognized as important because the decisions to be optimized were constrained by the need to respect many upper or lower bounds on their feasibility. A new kind of mathematical analysis, beyond traditional calculus, had to be developed to address these needs. It built first on appealing to the convexity of sets and functions, but went on to amazingly broad and successful concepts of variational geometry, subgradients, subderivatives, and variational convergence beyond just that. This talk will explain these revolutionary developments and why there were essential.
Event date: 1/11/2022
Speaker: Prof. Terry Rockafellar (University of Washington)
Hosted by: Department of Applied Mathematics
- Subjects:
- Mathematics and Statistics
- Keywords:
- Convex functions Convex sets Mathematical optimization Computer science -- Mathematics
- Resource Type:
- Video
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Video
Geospatial information science is a discipline that focuses on using geospatial information technology to understand people, places, nature and processes of the earth. IoT refers to Internet of things, the combination of sensors, software and other technologies to connect and exchange data with other devices and systems over the Internet. The era of IoT brings us opportunities and challenges for geospatial information science. In the keynote, five characteristics and three scientific issues of geo-spatial information science in the era of IoT are summarised.
Even date: 6/9/2022
Speaker: Prof. Daren Li
Moderator: Prof. Christopher Chao (Hong Kong Polytechnic University)
Panel members: Prof. Qingyan Chen, Prof. Qinhao Chen (Hong Kong Polytechnic University)
Hosted by: PolyU Academy for Interdisciplinary Research
- Subjects:
- Land Surveying and Geo-Informatics
- Keywords:
- Internet of things Geospatial data Spatial data mining
- Resource Type:
- Video
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Video
Adaptive computation is of great importance in numerical simulations. The ideas for adaptive computations can be dated back to adaptive finite element methods in 1970s. In this talk, we shall first review some recent development for adaptive methods with some application. Then, we will propose a deep adaptive sampling method for solving PDEs where deep neural networks are utilized to approximate the solutions. In particular, we propose the failure informed PINNs (FI-PINNs), which can adaptively refine the training set with the goal of reducing the failure probability. Compared with the neural network approximation obtained with uniformly distributed collocation points, the proposed algorithms can significantly improve the accuracy, especially for low regularity and high-dimensional problems.
Event date: 18/10/2022
Speaker: Prof. Tao Tang (Beijing Normal University-Hong Kong Baptist University United International College)
Hosted by: Department of Applied Mathematics
- Subjects:
- Mathematics and Statistics
- Keywords:
- Sampling (Statistics) Differential equations Partial -- Numerical solutions Mathematical models Adaptive computing systems
- Resource Type:
- Video
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Video
Convex Matrix Optimization (MOP) arises in a wide variety of applications. The last three decades have seen dramatic advances in the theory and practice of matrix optimization because of its extremely powerful modeling capability. In particular, semidefinite programming (SP) and its generalizations have been widely used to model problems in applications such as combinatorial and polynomial optimization, covariance matrix estimation, matrix completion and sensor network localization. The first part of the talk will describe the primal-dual interior-point methods (IPMs) implemented in SDPT3 for solving medium scale SP, followed by inexact IPMs (with linear systems solved by iterative solvers) for large scale SDP and discussions on their inherent limitations. The second part will present algorithmic advances for solving large scale SDP based on the proximal-point or augmented Lagrangian framework In particular, we describe the design and implementation of an augmented Lagrangian based method (called SDPNAL+) for solving SDP problems with large number of linear constraints. The last part of the talk will focus on recent advances on using a combination of local search methods and convex lifting to solve low-rank factorization models of SP problems.
Event date: 11/10/2022
Speaker: Prof. Kim-Chuan Toh (National University of Singapore)
Hosted by: Department of Applied Mathematics
- Subjects:
- Mathematics and Statistics
- Keywords:
- Convex programming Semidefinite programming
- Resource Type:
- Video
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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
Machine learning can deliver unprecedented performance. Its application domain has expanded into safety-critical cyber-physical systems such as UAVs and self-driver cars. However, the safety assurance of vehicular control has two conditions: 1) an analytical model of system behaviors such as provable stability, and 2) the software safety certification process (e.g., DO 178C) requires that the software be simple enough so that software safety can be validated by a combination of model checking and near exhaustive testing. Although ML software, as is, does not meet these two safety requirements, the real-time physics model supervised ML architecture holds the promise to 1) meet the two safety requirements and 2) enable ML software to safely improve control performance and safely learn from its experience in real-time. This talk will review the structure of the proposed architecture and some methods to embed physics into ML-enabled CPS control.
Event Date: 12/05/2022
Speaker: Prof. Lui Sha (University of Illinois Urbana-Champaign)
Hosted by: Graduate School
- Subjects:
- Aeronautical and Aviation Engineering and Computing
- Keywords:
- Machine learning Vehicles Remotely piloted Computer software -- Reliability Drone aircraft
- Resource Type:
- Video
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Video
The textile and fashion industry is in troubled times. Hong Kong is no exception. Our traditional market, the US, while difficult since 2018, has been dire in the covid pandemic. The industry is in the mist of disruptive changes brought by technological revolutions, in particular digitalization, and the retreat of globalism. But troubles always come with opportunities. Dr Henry Tan will give an overview on the outlook of the industry and his view on where opportunities are knocking.
Event date: 25/02/2021
Speaker: Dr Henry Tan (CEO, Luen Thai Group Ltd)
Hosted by: Institute of Textiles and Clothing
- Subjects:
- Fashion retailing and merchandising
- Keywords:
- Clothing trade -- China -- Hong Kong Clothing trade -- Technological innovations
- Resource Type:
- Video
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Video
Ms Shirley Chan, BBS, JP, Vice Chairman of YGM Trading Ltd. shared her insights on the trend of global fashion supply chain under the "New Normal".
Event date: 24/11/2020
Speaker: Ms Shirley Chan (Vice Chairman, YGM Trading Limited)
Facilitators: Dr Chris Lo (ITC), Dr Fan Di (ITC)
Hosted by: Institute of Textiles and Clothing
- Subjects:
- Fashion retailing and merchandising
- Keywords:
- Clothing trade COVID-19 Pemic (2020-) Clothing trade -- Technological innovations
- Resource Type:
- Video
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Video
Air transport liberalisation has been marked by two major developments, i.e. the advent of the hub-and-spoke network and the emergence of Low Fare Airlines (LFAs). All major Full Service Network Carrier (FSNCs) have heavily relied on hub operations to effectively compete in the long-haul market against LFAs which until recently focused on point-to-point, short-haul services. Recent competiton dynamics, however, have led to the gradual blurring of the different airline business models. LFAs have now established strong bases in satellite/airports and/or in low-cost terminals of major airports. Moreover, they have introduced long-haul flights thus competing with FSNCs at a new level. The lecture will highlight all the above issues focusing on their strategic business and geopolitical implications for aiport hubs. It will also discuss how Hong Kong International Airport can build on its current advantages to play focal role in the new environment.
Event Date: 16/06/2017
Speaker: Prof. Andreas Papatheodorou (University of Aegean)
Hosted by: School of Hotel and Tourism Management
- Subjects:
- Hotel, Travel and Tourism
- Keywords:
- Hong Kong International Airport Aeronautics Commercial Airlines -- Rates Airports
- Resource Type:
- Video
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Video
Using UC Berkeley as an exemplar, Prof. Koshland gave us a distinguished lecture on ‘Lighting the Way with Interdisciplinary Research since 1868’. One of the hallmarks of UC Berkeley has always been engagement of its faculty and students in research and education that expand in cross disciplines, joining on multiple approaches to address major challenges facing the world today, which is also what we are seeking to do at PAIR of PolyU. Moreover, Prof. Koshland shared with us the ways in which individuals and institutions can engage in interdisciplinary and multi-disciplinary research and education and how they can be creatively intertwined.
Event Date: 22/4/2022
Speaker: Prof. Catherine P. Koshland (University of California, Berkeley)
Moderator: Prof. Christopher Chao (Hong Kong Polytechnic University)
Panel members: Prof. Xiang-dong Li, Prof. Yuguo Li (Hong Kong Polytechnic University)
Hosted by: PolyU Academy for Interdisciplinary Research
- Keywords:
- Interdisciplinary research Interdisciplinary approach in education
- Resource Type:
- Video
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Video
This presentation will discuss the future of global universities within the evolving context of current international education systems. It will begin with an overview of the challenges posed to modern day universities by the breadth and diversity of international further education curricular between the ages of 16 and 18 and the accessibility of world leading universities to international students, in general. Having established potential global trends in further education, the implications for global universities and higher education will be discussed within the context of both teaching and research
Event Date: 17/05/2022
Speaker: Prof. David Cardwell (University of Cambridge)
Moderator: Prof. Christoper Chao (Hong Kong Polytechnic University)
Panel members: Prof. Wong Kwok-yin (Hong Kong Polytechnic University), Prof. Andrew Cohen (Hong Kong University of Science and Technology)
Hosted by: PolyU Academy for Interdisciplinary Research
- Keywords:
- International education Universities colleges -- Administration Education Higher
- Resource Type:
- Video