Events
Department of Mathematics and Statistics
Texas Tech University
Colloquium flyer
Even if the ongoing digital transformation of industry and society presents great possibilities when it comes to efficiency, performance and adaptation, it exposes systems to new risks and vulnerabilities. Security and privacy is of growing concern in many control applications. Cyber-attacks are frequently reported for a variety of industrial and infrastructure systems. For more than a decade the control community has developed techniques for how to design control systems resilient to cyber-physical attacks. In this talk, we will review some of these results. In particular, as cyber and physical components of networked control systems are tightly interconnected, it is argued that traditional IT security focusing only on the cyber part does not provide appropriate solutions. Modeling the objectives and resources of the adversary together with the plant and control dynamics is shown to be essential. The consequences of common attack scenarios, such as denial-of-service, replay, and bias injection attacks, can be analyzed using the proposed framework. It is also shown how to strengthen the control loops by deriving security- and privacy-aware estimation and control schemes. Applications in building automation, power networks, and automotive systems will be used to motivate and illustrate the results. The presentation is based on joint work with several students and colleagues at KTH and elsewhere.
Colloquium flyer
While the long-term benefits of introducing connected and automated vehicles into road traffic are widely understood to be revolutionary, there is much debate about whether its early stages will cause an increase in congestion and issues related to human-driven vehicles. Notwithstanding, connected vehicles acting as mobile sensors and actuators could enable traffic predictions and control at a scale never before possible, and thereby a much more efficient use of the available road infrastructure. In this talk, we will present how a new freight transport technology based on automated truck platoons can be the backbone for such a system. Some basic theoretical and experimental results on the control and coordination of truck platoons will be presented. How such platoons influence traffic flows by acting as a moving bottleneck will be discussed together with traffic models suitable for designing novel traffic control systems. It will also be argued that these models are possible to learn automatically from data gathered by platoons acting as traffic flow sensors. Experiments show that relatively few connected vehicles are enough to mitigate stop-and-go waves and improve traffic conditions significantly. The presentation is based on joint work with Matthieu Barreau, Mladen Cicic, and others.
The annual spring Departmental Awards Ceremony honoring student scholarship, Departmental Excellence, and SIAM award recipients is a hybrid event and can be seen in Math 011 or attended Wednesday the 27th at 4:00 PM CDT (UT-5) via this Zoom link. Meeting ID: 964 5740 5000 no passcode
Following the online ceremony, an in-person joint Reception, graciously sponsored by Dr. Ghosh, for acclaimed Dayawansa Memorial Speaker Professor Karl Henrik Johansson and Honors Ceremony recipients will be held at 4:45 PM in the 1st Floor Lobby of the Math Buidling.
Colloquium flyer
Traditional control methods, such as model predictive control, are able to efficiently incorporate state and input constraints into the control synthesis problem. In this talk, we will discuss how more complex specifications based on linear temporal logic (LTL) can be included. We introduce the new notion of a temporal logic trees (TLT) and show how they can be derived from any LTL formula using classical reachability analysis. Conditions are given to verify whether a system satisfies an LTL formula by using TLT. The presented framework allows the treatment of uncertain and time-varying systems as well as environment models, different from many other approaches. We give an online control synthesis algorithm, under which a set of feasible control inputs can be generated at each time step and show that this algorithm is recursively feasible. The proposed method is demonstrated in applications of automated vehicles and shared-autonomy systems. The talk is mainly based on joint work with Yulong Gao, Frank Jiang, Mirco Giacobbe, and Alessandro Abate.
Solid tumours develop much like a fortress, acquiring characteristics that protect them against invasion. A common trait observed in solid tumours is the synthesis of excess collagen which traps therapeutic agents, resulting in a lack of dispersion of treatment within the tumour mass. In most tumours, this results in only a localised treatment. Often the tumour quickly recovers and continues to invade surrounding regions. Anti-tumour viral therapy is no exception to this rule. Experimental results show collagen density affects virus diffusion and inhibits cell infection; therefore, accurately modelling virus dispersion is an important aspect of modelling virotherapy. Mathematical models generally focus on the interaction between cancer cells and collagen. In this project, we aim to accurately capture virotherapy outcome in relation to collagen density in the tumour environment. Beginning with a random walk, we derive a novel non-Fickian diffusion term for virus dispersion and show that this diffusion term captures virus dispersion in dense collagen. Applying this diffusion term to a system of reaction-diffusion equations, we validate our model against experimental results and show that our model can predict treatment outcome in different collagen structures. The results demonstrate that collagen density is an important predictor of tumour response to therapy, and that standard Fickian diffusion cannot sufficiently capture virus spread in collagen-dense tumours.
The Biomath seminar may be attended Monday the 25th at 4:00 PM CDT (UT-5) via this Zoom link. Meeting ID: 839 9465 7333 Passcode: BfriM6
Please virtually attend this week's Statistics seminar at 4:00 PM Monday the 25th via this zoom link
Meeting ID: 981 8679 7252
Passcode: 271865
In this talk, based on a joint paper by Prof. Dimitrios Betsakos
from the Aristotle University of Thessaloniki in Greece,
Prof. Matti Vuorinen from the University of Turku in Finland and the
presenter, we will discuss problems concerning the conformal capacity of ``hedgehogs'', which are compact sets $E$ in the unit
disk $\mathbb{D}=\{z:\,|z|<1\}$ consisting of a central body $E_0$
that is typically a smaller disk
$\overline{\mathbb{D}}_r=\{z:\,|z|\le r\}$, $r\in(0,1)$, and several
spikes $E_k$ that are compact sets lying on radial intervals
$I(\alpha_k)=\{te^{i\alpha_k}:\,0\le t<1\}$. The main questions we
are concerned with are the following: (1) How does the conformal
capacity ${\rm cap}(E)$ of $E=\cup_{k=0}^n E_k$ behave when the
spikes $E_k$, $k=1,\ldots,n$, move along the intervals
$I(\alpha_k)$ toward the central body if their hyperbolic lengths
are preserved during the motion? (2) How does the
capacity ${\rm cap}(E)$ depend on the distribution of
angles between the spikes $E_k$? We prove several results related
to these questions and discuss methods of applying symmetrization
type transformations to study the capacity of hedgehogs. Several
open problems, including problems on the
capacity of hedgehogs in the three-dimensional
hyperbolic space, also will be suggested.
To join the talk on Zoom please click
here.
While environmental, social, and governance (ESG) trading activity has been a distinctive feature of financial markets,
the debate if ESG scores can also convey information regarding a company’s riskiness remains open.
Regulatory authorities, such as the European Banking Authority (EBA), have acknowledged that ESG factors can contribute to risk.
Therefore, it is important to model such risks and quantify what part of a company’s riskiness can be attributed to the ESG scores.
This paper aims to question whether ESG scores can be used to provide information on (tail) riskiness.
By analyzing the (tail) dependence structure of companies with a range of ESG scores, that is within an ESG rating class,
using high-dimensional vine copula modelling, we are able to show that risk can also depend on and be directly associated with
a specific ESG rating class.
Empirical findings on real-world data show positive not negligible ESG risks determined by ESG scores, especially during the 2008 crisis.
Please virtually attend this week's second Statistics seminar at 3:00 PM Friday the 29th via this zoom link
Meeting ID: 942 0486 6435
Passcode: 909439