pwc-archive/papers-with-abstracts huggingface dataset:
Stability of Switched Affine Systems: Arbitrary and Dwell-Time Switching
Authors: Matteo Della Rossa, Lucas N. Egidio, Raphaël M. Jungers
Date: 2022-03-14 00:00:00

The dynamical behavior of switched affine systems is known to be more intricate than that of the well-studied switched linear systems, essentially due to the existence of distinct equilibrium points for each subsystem. First, under arbitrary switching rules, the stability analysis must be generally carried out with respect to a compact set with non-empty interior rather than to a singleton. We provide a novel proof technique for existence and outer approximation of attractive invariant sets of a switched affine system, under the hypothesis of global uniform stability of its linearization. On the other hand, considering dwell-time switching signals, forward invariant sets need not exist for this class of switched systems, even for stable ones. Hence, more general notions of stability/boundedness are introduced and studied, highlighting the relations of these concepts to the uniform stability of the linear part of the system under the same class of dwell-time switching signals. These results reveal the main differences and specificities of switched affine systems with respect to linear ones, providing a first step for the analysis of switched systems composed by subsystems not sharing the same equilibrium. Numerical methods based on linear matrix inequalities and sum-of-squares programming are presented and illustrate the developed theory.
Exponentially stable adaptive control. Part I. Time-invariant plants
Authors: Anton Glushchenko, Kostantin Lastochkin, Vladislav Petrov
Date: 2022-03-14 00:00:00

In this research we consider linear time-invariant plants and assume that the regressor finite excitation requirement is met. In such case, a new law to adjust the controller parameters, which ensures the exponential stability of the classical dynamic model of the tracking error under the condition that its states are not included in such a law, is proposed in this study. In addition, it also relaxes a number of classical assumptions and requirements of the adaptive control theory, i.e. the necessity to know the sign/value of the plant high-frequency gain, the need of experimentally based choice of the proposed law adaptive gain value, the requirement to the tracking error transfer function to be strictly positive real considering the output feedback control. The applicability of the proposed law to the problems of adaptive state and output feedback control is shown. The advantages of the proposed method over the well-known ones are demonstrated.
Data-Driven Robust Control for Discrete Linear Time-Invariant Systems: A Descriptor System Approach
Authors: Jiabao He, Xuan Zhang, Feng Xu, Junbo Tan, Xueqian Wang
Date: 2022-03-14 00:00:00

Given the recent surge of interest in data-driven control, this paper proposes a two-step method to study robust data-driven control for a parameter-unknown linear time-invariant (LTI) system that is affected by energy-bounded noises. First, two data experiments are designed and corresponding data are collected, then the investigated system is equivalently written into a data-based descriptor system with structured parametric uncertainties. Second, combined with model-based control theory for descriptor systems, state feedback controllers are designed for such data-based descriptor system, which stabilize the original LTI system and guarantee the ${H_\infty}$ performance. Finally, a simulation example is provided to illustrate the effectiveness and merits of our method.
Robust Event Triggering Control for Lateral Dynamics of Intelligent Vehicles with Designable Inter-event Times
Authors: Xing Chu, Zhi Liu, Lei Mao, Xin Jin, Zhaoxia Peng, Guoguang Wen
Date: 2022-03-14 00:00:00

In this brief, an improved event-triggered update mechanism (ETM) for the linear quadratic regulator is proposed to solve the lateral motion control problem of intelligent vehicle under bounded disturbances. Based on a novel event function using a clock-like variable to determine the triggering time, we further introduce two new design parameters to improve control performance. Distinct from existing event-based control mechanisms, the inter-event times (IETs) derived from the above control framework are designable, meaning that the proposed ETM can be deployed on practical vehicle more easily and effectively. In addition, the improved IETs-designable ETM features a global robust event-separation property that is extremely required for practical lateral motion control of vehicle subject to diverse disturbances. Theoretical analysis proves the feasibility and stability of the proposed control strategy for trajectory tracking under bounded disturbances. Finally, simulation results verify the theoretical results and show the advantages of the proposed control strategy.
Real-Time Electric Vehicle Smart Charging at Workplaces: A Real-World Case Study
Authors: Nathaniel Tucker, Gustavo Cezar, Mahnoosh Alizadeh
Date: 2022-03-14 00:00:00

We study a real-time smart charging algorithm for electric vehicles (EVs) at a workplace parking lot in order to minimize electricity cost from time-of-use electricity rates and demand charges while ensuring that the owners of the EVs receive adequate levels of charge. Notably, due to real-world constraints, our algorithm is agnostic to both the state-of-charge and the departure time of the EVs and uses scenario generation to account for each EV's unknown future departure time as well as certainty equivalent control to account for the unknown EV arrivals in the future. Real-world charging data from a Google campus in California allows us to build realistic models of charging demand for each day of the week. We then compare various results from our smart charging algorithm to the status quo for a two week period at a Google parking location.
The development of battery storage systems in Germany: A market review (status 2023)
Authors: Jan Figgener, Christopher Hecht, David Haberschusz, Jakob Bors, Kai Gerd Spreuer, Kai-Philipp Kairies, Peter Stenzel, Dirk Uwe Sauer
Date: 2022-03-13 00:00:00
Tasks: Decision Making

The market for battery storage systems (BSS) has been growing rapidly for years and will multiply in the future. With this extension of our previous works, we contribute key figures for model parametrization and political decision-making and depict the market development in Germany, one of the leading storage markets worldwide. In empirical analyses, we evaluate and combine all major public databases on national stationary and mobile storage as well as our databases from subsidy programs and extend the insights by literature research and bilateral industry exchange. In comparison to 2021, the market for home storage systems (HSS) grew by 52% in terms of battery energy in 2022 and is by far the largest stationary storage market in Germany. We estimate that about 220,000 HSS (1.9 GWh / 1.2 GW) were installed solely in 2022. The emerging market for industrial storage systems (ISS) grew by 24% in 2022, with a total of 1,200 ISS (0.08 GWh / 0.04 GW) installed. The market for large-scale storage systems (LSS) increased strongly by 910% with 47 LSS (0.47 GWh / 0.43 GW) commissioned. The electric vehicle (EV) market grew with 693,000 new EV (27 GWh / 43 GW (DC) / 4.5 GW (AC)) by 34% in terms of battery energy. System BSS prices increased significantly in 2022 and were estimated at 1,200 EUR/kWh for HSS. LSS prices ranged on average from 310 EUR/kWh to 465 EUR/kWh. In total, we estimate that over 650,000 stationary BSS with a battery energy of 7.0 GWh with an inverter power of 4.3 GW and 1,878,000 EV with a battery energy of 65 GWh and a DC charging power of 91 GW (12 GW AC) were operated in Germany by the end of 2022. The cumulative battery energy of about 72 GWh is therefore nearly twice the 39 GWh of nationally installed pumped hydro storage demonstrating the enormous flexibility potential of battery storage for the energy system.
PMU-Driven Non-Preemptive Disconnection of Overhead Lines at the Approach or Break-Out of Forest Fires
Authors: Panayiotis Moutis, Uday Sriram
Date: 2022-03-13 00:00:00

The number and intensity of forest fires in the United States have been steadily increasing and causing massive economic and ecological damage. Overhead transmission and distribution lines are typically disconnected preemptively near fires, a practice that causes high social cost. Deployment of Phasor Measurement Units (PMUs) and their ability for synchronized real-time measurement of voltage and current inspire the here proposed method for the just-in-time disconnection of overhead lines at the ignition or approach of fires. PMUs can detect ambient temperature changes caused by fires through the change of line resistance. An ambient temperature model at the vicinity of a fire seat and the dynamic heat exchange model of the IEEE 738 dynamic line rating standard for bare overhead conductors are used in MATLAB Simulink to assess the performance of the proposed control method. Extensive testing shows that, under various conditions, the proposed technique can detect a forest fire approaching an overhead line, while avoiding, almost completely, any false alarms.
A Stochastic Binary Vertex-Triggering Resetting Algorithm for Global Synchronization of Pulse-Coupled Oscillators
Authors: Muhammad U. Javed, Jorge I. Poveda, Xudong Chen
Date: 2022-03-13 00:00:00

In this paper, we propose a novel stochastic binary resetting algorithm for networks of pulse-coupled oscillators (or, simply, agents) to reach global synchronization. The algorithm is simple to state: Every agent in a network oscillates at a common frequency. Upon completing an oscillation, an agent generates a Bernoulli random variable to decide whether it sends pulses to all of its out-neighbors or it stays quiet. Upon receiving a pulse, an agent resets its state by following a binary phase update rule. We show that such an algorithm can guarantee global synchronization of the agents almost surely as long as the underlying information flow topology is a rooted directed graph. The proof of the result relies on the use of a stochastic hybrid dynamical system approach. Toward the end of the paper, we present numerical demonstrations for the validity of the result and, also, numerical studies about the times needed to reach synchronization for various information flow topologies.
Adaptive Bit Rate Control in Semantic Communication with Incremental Knowledge-based HARQ
Authors: Qingyang Zhou, Rongpeng Li, Zhifeng Zhao, Yong Xiao, Honggang Zhang
Date: 2022-03-13 00:00:00
Tasks: Semantic Communication

Semantic communication has witnessed a great progress with the development of natural language processing (NLP) and deep learning (DL). Although existing semantic communication technologies can effectively reduce errors in semantic interpretation, most of these solutions adopt a fixed bit length structure, along with a rigid transmission scheme, which is inefficient and lacks scalability when faced with different meanings and signal-to-noise ratio (SNR) conditions. In this paper, we explore the impact of adaptive bit lengths on semantic coding (SC) under various channel conditions. First, we propose progressive semantic hybrid automatic repeat request (HARQ) schemes that utilize incremental knowledge (IK) to simultaneously reduce the communication cost and semantic error. On top of this, we design a novel semantic encoding solution with multi-bit length selection. In this fashion, the transmitter employs a policy network to decide the appropriate coding rate, so as to secure the correct information delivery at the cost of minimal bits. Moreover, a specific denoiser is further introduced to reduce the semantic errors encountered in the transmission process according to the semantic characteristics of context. Extensive simulation results have been conducted to verify the effectiveness of the proposed solution.
Spectral Graph Clustering for Intentional Islanding Operations in Resilient Hybrid Energy Systems
Authors: Jiaxin Wu, Xin Chen, Sobhan Badakhshan, Jie Zhang, Pingfeng Wang
Date: 2022-03-13 00:00:00
Tasks: Clustering, Graph Clustering, Spectral Graph Clustering

Establishing cleaner energy generation therefore improving the sustainability of the power system is a crucial task in this century, and one of the key strategies being pursued is to shift the dependence on fossil fuel to renewable technologies such as wind, solar, and nuclear. However, with the increasing number of heterogeneous components included, the complexity of the hybrid energy system becomes more significant. And the complex system imposes a more stringent requirement of the contingency plan to enhance the overall system resilience. Among different strategies to ensure a reliable system, intentional islanding is commonly applied in practical applications for power systems and attracts abundant interest in the literature. In this study, we propose a hierarchical spectral clustering-based intentional islanding strategy at the transmission level with renewable generations. To incorporate the renewable generation that relies on the inverter technology, the frequency measurements are considered to represent the transient response. And it has been further used as embedded information in the clustering algorithm along with other important electrical information from the system to enrich the modeling capability of the proposed framework. To demonstrate the effectiveness of the islanding strategy, the modified IEEE-9 bus and IEEE-118 bus systems coupled with wind farms are considered as the test cases.
Cyclone Preparedness, Rescue Operations and Damage Assessment using UAVs
Authors: Rudrashis Majumder, Shuvrangshu Jana, Prathyush P. Menon, Debasish Ghose, N. M. Prusty, Bipasha Mukherjee, Aditi Ghosh
Date: 2022-03-12 00:00:00
Tasks: Management

UAV's capability to access remote and inaccessible areas within a quick time can be utilized for effective cyclone management. This paper presents the possible application of UAVs at different stages of cyclone mitigation. The overall system architecture necessary for preparedness, rescue operation, resource allocation, and damage assessment using UAVs during cyclones is described. Although general commercial UAVs are reported to be used in cyclone operations, UAV systems should be planned specifically for cyclone operations to improve efficiency. Here, the specification required for effective and safe UAV operations in the post-cyclone scenario is presented. Mission planning required for various rescue, relief, and damage assessment missions related to cyclone management is discussed. A case study of deploying UAV in Amphan cyclone operation in West Bengal is also presented. This paper can help disaster management authorities to develop UAV systems specifically to cater to cyclone operations.
Resilient UAV Formation for Coverage and Connectivity of Spatially Dispersed Users
Authors: Yuhui Wang, Junaid Farooq
Date: 2022-03-11 00:00:00

Unmanned aerial vehicles (UAVs) are a convenient choice for carrying mobile base stations to rapidly setup communication services for ground users. Unlike terrestrial networks, UAVs do not have fiber optic back-haul connectivity except when they are tethered to the ground, which restricts their mobility. In the absence of back-haul, e.g., in remote areas, emergency situations, or in battlefields, there is a need to ensure connectivity among UAVs in addition to coverage of ground users for creating local area networks. This paper provides a distributed and dynamic approach for UAV formation-based control for coverage and connectivity of spatially dispersed users. We use flocking dynamics as a guide to constructing tailored formations of UAVs on the fly. Simulation results demonstrate that if sufficient aerial base stations are available, the proposed approach results in a strongly connected network of UAVs that is able to provide both a backhaul and fronthaul network. The approach can be further extended to create multi-tier extra-terrestrial networks to cater for large-scale applications.
Distributed Dual Quaternion Based Localization of Visual Sensor Networks
Authors: Luca Varotto, Marco Fabris, Giulia Michieletto, Angelo Cenedese
Date: 2022-03-11 00:00:00
Tasks: Distributed Optimization, Position

In this paper we consider the localization problem for a visual sensor network. Inspired by the alternate attitude and position distributed optimization framework discussed in [1], we propose an estimation scheme that exploits the unit dual quaternion algebra to describe the sensors pose. This representation is beneficial in the formulation of the optimization scheme allowing to solve the localization problem without designing two interlaced position and orientation estimators, thus improving the estimation error distribution over the two pose components and the overall localization performance. Furthermore, the numerical experimentation asserts the robustness of the proposed algorithm w.r.t. the initial conditions.
Thermal circuits assembling and state-space extraction for modelling heat transfer in buildings
Authors: Christian Ghiaus, Naveed Ahmad
Date: 2022-03-08 00:00:00

State-space representation is essential in the theory of dynamic systems. This paper introduces a methodology for obtaining state-space representation from the thermal models of elementary components of a building by the conjunction of two methods: 1) assembling of thermal circuits and 2) state-space extraction from thermal circuit. These methods are fully illustrated on a very simple model and tested on a real house of about 100 m 2 on which detailed measurements were achieved for 40 days at a time step of 10 min. The errors obtained between the measurements and the simulation results are in the order of $\pm$1 {\textdegree}C for a single zone and $\pm$2 {\textdegree}C for seven thermal zones. Besides simulation, parameter identification and control, the methods for assembling thermal circuits and extraction of state-space representation may be useful in Building Information Modelling (BIM).
Core packing of well-defined x-ray and NMR structures is the same
Authors: Alex T. Grigas, Zhuoyi Liu, Lynne Regan, Corey S. O'Hern
Date: 2022-03-12 00:00:00

Numerous studies have investigated the differences and similarities between protein structures determined by solution NMR spectroscopy and those determined by x-ray crystallography. A fundamental question is whether any observed differences are due to differing methodologies, or to differences in the behavior of proteins in solution versus in the crystalline state. Here, we compare the properties of the hydrophobic cores of high-resolution protein crystal structures and those in NMR structures, determined using increasing numbers and types of restraints. Prior studies have reported that many NMR structures have denser cores compared to those of high-resolution x-ray crystal structures. Our current work investigates this result in more detail, and finds that these NMR structures tend to violate basic features of protein stereochemistry, such as small non-bonded atomic overlaps and few Ramachandran and side chain dihedral angle outliers. We find that NMR structures solved with more restraints, and which do not significantly violate stereochemistry, have hydrophobic cores that have a similar size and packing fraction as their counterparts determined by x-ray crystallography at high-resolution. These results lead us to conclude that, at least regarding the core packing properties, high-quality structures determined by NMR and x-ray crystallography are the same, and the differences reported earlier are most likely a consequence of methodology, rather than fundamental differences between the protein in the two different environments.
Adaptive movement strategy in rock-paper-scissors models
Authors: M. Tenorio, E. Rangel, J. Menezes
Date: 2022-03-12 00:00:00

Organisms may respond to local stimuli that benefit or threaten their fitness. The adaptive movement behaviour may allow individuals to adjust their speed to maximise the chances of being in comfort zones, where death risk is minimal. We investigate spatial cyclic models where the rock-paper-scissors game rules describe the nonhierarchical dominance. We assume that organisms of one out of the species can control the mobility rate in response to the information obtained from scanning the environment. Running a series of stochastic simulations, we quantify the effects of the movement strategy on the spatial patterns and population dynamics. Our findings show that the ability to change mobility to adapt to environmental clues is not reflected in an advantage in cyclic spatial games. The adaptive movement provokes a delay in the spatial domains occupied by the species in the spiral waves, making the group more vulnerable to the advance of the dominant species and less efficient in taking territory from the dominated species. Our outcomes also show that the effects of adaptive movement behaviour accentuate whether most individuals have a long-range neighbourhood perception. Our results may be helpful for biologists and data scientists to comprehend the dynamics of ecosystems where adaptive processes are fundamental.
Teleconnection patterns of different El Niño types revealed by climate network curvature
Authors: Felix M. Strnad, Jakob Schlör, Christian Fröhlich, Bedartha Goswami
Date: 2022-03-07 00:00:00
Tasks: Diversity

The diversity of El Ni\~no events is commonly described by two distinct flavors, the Eastern Pacific (EP) and Central Pacific (CP) types. While the remote impacts, i.e. teleconnections, of EP and CP events have been studied for different regions individually, a global picture of their teleconnection patterns is still lacking. Here, we use Forman-Ricci curvature applied on climate networks constructed from 2-meter air temperature data to distinguish regional links from teleconnections. Our results confirm that teleconnection patterns are strongly influenced by the El Ni\~no type. EP events have primarily tropical teleconnections whereas CP events involve tropical-extratropical connections, particularly in the Pacific. Moreover, the central Pacific region does not have many teleconnections, even during CP events. It is mainly the eastern Pacific that mediates the remote influences for both El Ni\~no types.
Encompassing Tests for Nonparametric Regressions
Authors: Elia Lapenta, Pascal Lavergne
Date: 2022-03-13 00:00:00
Tasks: regression

We set up a formal framework to characterize encompassing of nonparametric models through the L2 distance. We contrast it to previous literature on the comparison of nonparametric regression models. We then develop testing procedures for the encompassing hypothesis that are fully nonparametric. Our test statistics depend on kernel regression, raising the issue of bandwidth's choice. We investigate two alternative approaches to obtain a "small bias property" for our test statistics. We show the validity of a wild bootstrap method. We empirically study the use of a data-driven bandwidth and illustrate the attractive features of our tests for small and moderate samples.
Granular Linkages, Supplier Cost Shocks & Export Performance
Authors: Santiago Camara
Date: 2022-03-14 00:00:00

This paper presents evidence on the granular nature of firms' network of foreign suppliers and studies its implications for the impact of supplier shocks on domestic firms' performance. To demonstrate this, I use customs level information on transactions between Argentinean firms and foreign firms. I highlight two novel stylized facts: (i) the distribution of domestic firms' number of foreign suppliers is highly skewed with the median firm reporting linkages with only two, (ii) firms focus imported value on one top-supplier, even when controlling for firm size. Motivated by these facts I construct a theoretical framework of heterogeneous firms subject to search frictions in the market for foreign suppliers. Through a calibration exercise I study the framework's predictions and test them in the data using a shift-share identification strategy. Results present evidence of significant frictions in the market for foreign suppliers and strong import-export complementarities.