Hasil untuk "River protective works. Regulation. Flood control"

Abbas FathiAzar, Silvia De Angeli

ABSTRACT The integration of building‐level floodproofing into flood risk management frameworks is gaining increasing recognition. As property owners ultimately decide on implementation, and financial incentives can drive adoption, a critical gap remains: the absence of Building‐Specific, Context‐Sensitive, Micro‐Scale Risk Assessment (BC_MRA) frameworks that effectively support property owners and policymakers in their decision‐making. This study introduces a BC_MRA framework alongside a straightforward yet expandable risk‐based incentive structure, representing an innovative approach to enhancing property‐level floodproofing, hereby advancing flood resilience research. A key contribution is a systematic methodology that contextualizes all the components of micro‐scale flood risk assessment and the process for assessing the effectiveness of floodproofing interventions. The framework is applied to a case study in Pesaro, Italy, where dry and wet floodproofing strategies' financial viability and risk reduction potential are evaluated in response to riverine flood risk. Results underscore the importance of BC_MRA to inform effective micro‐scale flood mitigation, revealing that expected annual damage is not solely dependent on proximity to the river but is also significantly influenced by building‐specific vulnerability to flooding. Furthermore, wet floodproofing consistently resulted in longer payback periods compared with dry floodproofing, rendering it economically unviable for any of the buildings studied.

Parin Bhaduri, Adam B. Pollack, James Yoon et al.

ABSTRACT Coastal cities face increasing flood hazards due to climate change. Physical infrastructures, such as levees, are commonly used to reduce flood hazards. To effectively manage flood risks, it is important to understand the degree to which physical infrastructures change both hazard and exposure. For example, many studies suggest that levee construction causes an overall increase in risk because levees promote exposure growth to a greater degree than they reduce flood hazards. Although this so‐called “levee effect” is widely studied, there are knowledge gaps surrounding how uncertainties related to levee construction and flood risk translate into the occurrence and strength of the levee effect in coastal communities. Here, we use agent‐based modeling to simulate the influence of flood risk information pathways on the dynamics around the levee effect, first under idealized conditions and then within a real‐world coastal case study. We finally conduct a global sensitivity analysis to identify which model factors contribute to the strength of the levee effect. We find that, under idealized conditions, the strength of the levee effect is highly sensitive to economic (e.g., population growth) and engineering (e.g., levee failure) factors. However, under more complex coastal conditions, factors related to household behavior (e.g., risk aversion) are more influential on the strength of the levee effect. Overall, our findings emphasize the importance of capturing the interactions and uncertainties among multiple behavioral, economic, and engineering factors when measuring flood risk in coastal communities.

D. Janssen, S. N. Jonkman, A. J. M. Schmets et al.

ABSTRACT During extreme high‐water events in river systems, the load on a levee section may exceed its resistance, initiating the breaching process which eventually leads to levee failure. The success of an emergency measure to intervene in the initial phases of levee failure is mainly dependent on its timely application. Quick action is required to prepare and deploy an emergency measure before damages to the levee section have become irreparable. In this study, we investigate the key parameters for successful application of an emergency measure, focusing on the BresDefender case study. The BresDefender is a floating pontoon used by the Dutch military, which is intended to avoid or postpone levee failure. A model has been developed taking the operational steps in the implementation of the emergency measure during a high water and the (uncertainty) in the duration of these processes into account. The model is used to quantify the probability of successful operation to prevent levee failure due to overflow or slope instability. The probability of successful application of the BresDefender has been simulated for river flood situations in the Netherlands. For the river Rhine, where the examined cases were prone to slope instabilities, the probability of arriving in time was found to be 70%. But for the Meuse case, where the examined cases were prone to overflow, the probability of arriving in time was found to be only 0%. The critical steps in the process after the occurrence of damage to the levee are damage detection, the decision to repair the damage, the transport of the emergency measure, and the placement of the measure. By incorporating emergency measures in emergency preparedness procedures, the time required for the critical steps will be decreased and the probability of successful application of the emergency measure, i.e., its contribution to flood risk reduction, will be enhanced.

Ezekiel Olatunji, David Proverbs, Chaminda Pathirage et al.

ABSTRACT Flood risk management (FRM) strategies in many developed countries increasingly focus on building flood resilience at property, community, and national levels. However, existing research on community flood resilience (CFR) has thus far inadequately addressed the social dynamics underpinning interactions among key resilience dimensions. Despite limited recognition of the social dimension, factors such as social capital and sociocultural dynamics remain insufficiently explored, warranting further investigation. This study employs a modified preferred reporting items for systematic reviews and meta‐analyses (PRISMA) to critically review and synthesize research gaps, before presenting an innovative social capital oriented framework to evaluate CFR. While infrastructure, economic, environmental, human, and governance dimensions play significant roles, the proposed framework emphasizes the foundational role of social capital and sociocultural factors, including norms, values, and identities, in shaping resilience outcomes and actions. These factors influence the success or failure of resilience‐building efforts, particularly in diverse, deprived communities, such as those with nonnative speaking populations. This innovative framework offers insights for multisectoral stakeholders, including flood risk managers, engineers, surveyors, property owners, and local authorities, to address persistent challenges in resilience‐building activities and improve intervention outcomes.

Md Mostafizur Rahman, Mst. Nusrat Jahan Suchi, Abir Mohd Shakib Shahide et al.

ABSTRACT This study evaluates the flood risk of households in the flood‐prone Char areas of Dewanganj, Jamalpur, Bangladesh, focusing on sociodemographic factors, vulnerability, flood exposure, and capacity. Using survey data from 400 households, we found a predominance of male‐headed households, a high reliance on wage labor, and widespread substandard housing, all contributing to flood risk. The findings reveal a rise in flood frequency and home inundation; nearly all respondents (99.75%) confirm worsening flood conditions, indicating a long‐term climate trend rather than isolated events. Vulnerabilities are further heightened by low education levels (60.75% with no formal education), high poverty rates (98.75% below the national income average), and limited access to critical resources like durable housing and flood preparedness training. Regression analyses indicate significant associations between flood risk and factors like age, income source, and housing type (female‐headed households: p < 0.001, β = 0.06; age groups 36–45 and 46–55: p < 0.001, β = 0.07, and β = 0.11, respectively). The study highlights the need for targeted interventions, with the most critical recommendation being the improvement of housing resilience, especially for vulnerable groups such as female‐headed households and those in temporary structures. Enhanced flood forecasting, resilient infrastructure, and community‐based training programs are also essential for reducing flood risk and increasing adaptive capacity. Our findings provide actionable insights for policymakers and NGOs to develop tailored flood resilience strategies, offering a foundational model for flood‐prone communities across Bangladesh.

Josephine Thywill Katsekpor, Klaus Greve, Edmund I. Yamba et al.

ABSTRACT Flooding in Ghana's White Volta basin has caused widespread displacement, fatalities, and damage to infrastructure and livelihoods in agriculturally dependent communities. Despite the presence of national agencies such as the Ghana Meteorological Agency (GMet) and Ghana Hydrological Authority (GHA), early warning capabilities remain constrained by limited real‐time data, outdated infrastructure, and weak coordination. As a result, many residents continue to rely on traditional knowledge and informal coping strategies. This study qualitatively assesses the operational state of Flood Early Warning Systems (FEWS) in the White Volta basin, focusing on their effectiveness, limitations, and opportunities for improvement. Using semi‐structured interviews with 18 key stakeholders spanning government agencies, technical experts, and community leaders, we analysed the institutional and technical dynamics of Ghana's FEWS through thematic analysis. Findings reveal that although the myDEWETRA‐VOLTALARM platform offers 5‐day flood forecasts through social media, SMS, and radio, its warnings are often mistrusted or inaccessible to rural populations. Thematic analysis identified four critical gaps: institutional fragmentation, exclusion of local knowledge, inadequate data infrastructure, and last‐mile communication failures. These are complicated by the basin's unique environmental conditions, including transboundary dam releases, intense seasonal rainfall, flat terrain, and poor drainage. We conclude that the current FEWS framework remains insufficient for proactive flood risk governance. Strengthening institutional coordination, integrating community‐based adaptation practices, and investing in localized data and communication infrastructure are essential to improving system legitimacy and resilience. The study contributes to broader discourses on early warning systems in resource‐constrained settings.

Robert R. Bitmead

'The cardinal sin in control is to believe that the plant is given' Karl Astrom. Astrom, a towering figure of control theory and practice and awardee of the 1993 IEEE Medal of Honor for his work on adaptive control, provides this assessment of the obstinate part of realizing a feedback controller. And yet we are exhorted to rely on solely-data-driven methods of control design skipping the modeling and plant identification phases entirely. What is going on? Whom should we trust? How do we reconcile the implied ease (or indeed avoidance) of modeling with the steely focus on robustness of the control and the capacity of feedback to accommodate uncertainty? This paper seeks to investigate this subject with the objective of appreciating not whom to trust but what are the circumstances where the direct paradigm of control design from any lightly qualified data set provides a sensible way forward. Here is a clue: It depends on the confidence of your contentions about the plant system, the detailed data themselves and your appetite for failure. The paper attempts to segue repeatedly between the broad philosophical context and hard engineering examples. To instantiate ideas and add detail to vagaries, we incorporate a number of examples, each validated by their demonstrated commercial and industrial viability and each terminating with ein Blickwinkel or perspective in German. As David Wallace-Wells poses, before investing hundreds of billions of dollars we really ought to ask what is the trillion-dollar problem which might potentially be solved. By sticking to industrially proven technologies, we hope to delineate what works suitably well in practice or was judged worthy of the risk.

Xinyuan Liang, Longhao Qian, Yi Lok Lo et al.

This paper presents a robust neural control design for a three-drone slung payload transportation system to track a reference path under external disturbances. The control contraction metric (CCM) is used to generate a neural exponentially converging baseline controller while complying with control input saturation constraints. We also incorporate the uncertainty and disturbance estimator (UDE) technique to dynamically compensate for persistent disturbances. The proposed framework yields a modularized design, allowing the controller and estimator to perform their individual tasks and achieve a zero trajectory tracking error if the disturbances meet certain assumptions. The stability and robustness of the complete system, incorporating both the CCM controller and the UDE compensator, are presented. Simulations are conducted to demonstrate the capability of the proposed control design to follow complicated trajectories under external disturbances.

Armin Gießler, Felix Strehle, Jochen Illerhaus et al.

In this paper, we propose a novel dynamic state-feedback controller for polytopic linear parameter-varying (LPV) systems with constant input matrix. The controller employs a projected gradient flow method to continuously improve its control law and, under established conditions, converges to the optimal feedback gain of the corresponding linear quadratic regulator (LQR) problem associated with constant parameter trajectories. We derive conditions for quadratic stability, which can be verified via convex optimization, to ensure exponential stability of the LPV system even under arbitrarily fast parameter variations. Additionally, we provide sufficient conditions to guarantee the boundedness of the trajectories of the dynamic controller for any parameter trajectory and the convergence of its feedback gains to the optimal LQR gains for constant parameter trajectories. Furthermore, we show that the closed-loop system is asymptotically stable for constant parameter trajectories under these conditions. Simulation results demonstrate that the controller maintains stability and improves transient performance.

حسین شیرانی, انیس اسدی, سمیه صدر et al.

مقدمه مدلSWAT، یک ابزار مناسب برای شبیه‌سازی فرایندهای هیدرولوژیکی است. این مدل به ورودی‌های زیادی نیاز دارند که غالبا به‌صورت مستقیم قابل اندازه‌گیری نیستند و یکی از اصلی‌ترین منابع عدم قطعیت در این مدل‌ها محسوب می‌شود. فرایند واسنجی می‌تواند با تعدیل و تطبیق این ورودی‌ها موجب کاهش عدم قطعیت در نتایج مدل شود. پژوهش‌ها نشان دادند که واسنجی یک مدل هیدرولوژیکی با استفاده از الگوریتم‌های متداول واسنجی خودکار رزومه، دقت مناسبی در پیش‌بینی متغیرهای هیدرولوژیکی در دوره اعتبار‌سنجی به وجود نخواهد آورد. لذا، به‌منظور واسنجی مدل SWAT از الگوریتم PSO استفاده شد. از آنجا که هیچ قانون ریاضی و منطقی برای تعیین بهترین ترکیب پارامترهای الگوریتم PSO وجود ندارد و این ترکیب‌ها به اساس آزمون و خطا و از میان ترکیب‌های بسیار متنوع انتخاب می‌شوند، لذا، روش‌های مبتنی بر آزمون و خطا بسیار وقت‌گیر و گاهی غیر‌ممکن است. در این پژوهش، از روش تاگوچی برای تعیین بهترین ترکیب حاصل از پارامترهای الگوریتم PSO مورد استفاده قرار گرفت. مواد و روش‌‌‌ها در این پژوهش، قابلیت استفاده از مدل SWAT برای شبیه‌سازی رواناب ماهانه در حوزه آبخیز جوانمردی، از زیرحوضه‌های اصلی حوزه آبخیز لردگان با مساحت 380 کیلومتر مربع بررسی شد. در این پژوهش، پارامترهای الگوریتم PSO شامل تعداد شبیه‌سازی ‌(A)، تعداد تکرار ‌(B)، وزن محاسبه سرعت ‌(C) و پارامتر حرکت (D)، در چهار سطح تعریف شدند. سپس این پارامترها، مطابق آزمایش‌های موجود در آرایه متعامد L16 (با استفاده از روش طراحی آزمایش‌های تاگوچی)، طراحی و اجرا شدند. مقیاس عملکردی مورد استفاده برای ارزیابی الگوریتم‌ها، RPD (درصد انحراف نسبی) انتخاب شد. با توجه به ماهیت متغیر پاسخ در این پژوهش، برای تحلیل نتایج آزمایش تاگوچی از شاخص S/N "هر‌چه کمتر، بهتر" استفاده شد. مرحله انتخاب آرایه‌ها و محاسبات در نرم‌افزار Minitab 16 انجام گرفت. نتایج و بحث در مرحله تحلیل حساسیت که پیش از واسنجی مدل انجام شد، از میان 28 پارامتر مورد بررسی در این پژوهش، مدل نسبت به تغییرات 22 پارامتر حساسیت نشان داده و به‌عنوان متغیرهای اثرگذار بر شبیه‌سازی رواناب در حوزه آبخیز جوانمردی مشخص شدند. نتایج نشان داد که پارامتر عدد منحنی راواناب (CN)، مهمترین عامل و پارامترهای جرم مخصوص ظاهری خاک در حالت مرطوب (SOL_BD) و متوسط آب قابل استفاده به‌وسیله گیاه (SOL_AWC) به‌ترتیب در زمره مهمترین عوامل کنترل‌کننده دبی جریان در حوضه مطالعاتی هستند. بر اساس نتایج شبیه‌سازی شده به‌وسیله الگوریتم PSO مشخص شد که مدل SWAT دقت قابل قبولی برای برآورد رواناب ماهانه در منطقه مورد مطالعه دارد. به‌طوری‌‌که در مرحله واسنجی شاخص‌های r-factor و p-factor به‌ترتیب 1.23 و 0.88 و ضرایب تبیین و نش-‌ساتکلیف نیز به‌ترتیب برابر 0.77 و 0.75 بودند. در مرحله اعتبارسنجی نیز شاخص‌های r-factor و p-factor به‌ترتیب 1.31 و 0.84 و ضرایب تبیین و نش-‌ساتکلیف نیز به‌ترتیب برابر 0.72 و 0.73 بودند. در این پژوهش، بهترین ترکیب حاصل از کاربرد روش تاگوچی برای پارامتر‌های تعداد شبیه‌سازی، تعداد تکرار، وزن محاسبه سرعت و پارامترهای مناسب در الگوریتم PSO به‌ترتیب 40، 100، 0.2 و 0.15 (A4B4C4D3) تعیین شد. نتیجه گیری نتایج گویای این است که مدل SWAT، دقت قابل قبولی برای برآورد رواناب ماهانه در حوزه آبخیز جوانمردی داشته، روش PSO الگوریتم موثری در واسنجی و تعیین عدم قطعیت مدل در این حوضه بوده است. همچنین، استفاده از روش طراحی آزمایش‌ها تاگوچی، راهی مناسب برای تعیین بهترین ترکیب پارامترهای الگوریتم PSO برای محققانی است که از این روش برای بهینه‌سازی مدل SWAT استفاده می‌کنند.

Mohamed Camil Belhadjoudja, Miroslav Krstic, Emmanuel Witrant

Nonlinear convection, the source of turbulence in fluid flows, may hold the key to stabilizing turbulence by solving a specific cubic polynomial equation. We consider the incompressible Navier-Stokes equations in a two-dimensional channel. The tangential and normal velocities are assumed to be periodic in the streamwise direction. The pressure difference between the left and right ends of the channel is constant. Moreover, we consider no-slip boundary conditions, that is, zero tangential velocity, at the top and bottom walls of the channel, and normal velocity actuation at the top and bottom walls. We design the boundary control inputs to achieve global exponential stabilization, in the L2 sense, of a chosen Poiseuille equilibrium profile for an arbitrarily large Reynolds number. The key idea behind our approach is to select the boundary controllers such that they have zero spatial mean (to guarantee mass conservation) but non-zero spatial cubic mean. We reveal that, because of convection, the time derivative of the L2 energy of the regulation error is a cubic polynomial in the cubic mean of the boundary inputs. Regulation is then achieved by solving a specific cubic equation, using the Cardano root formula. The results are illustrated via a numerical example.

Daria Wiesława Krasiewicz, Grzegorz Wierzbicki

The origin and dynamics of a 2010 pluvial flood in the valley of a large European river are described. In order to study how local people perceive this catastrophic event a small administrative unit (rural municipality) within the Holocene floodplain (thus flooded to 90%) was chosen. Using a questionnaire a human-research survey was performed in the field among 287 people living in flood-prone areas. Almost half of the interviewees feel safe and do not expect a flood recurrence (interpreted as a levee effect). Seventeen percent believe the levee was intentionally breached due to political issues. Six percent of interviewees link the breach with small mammals using levees as a habitat, e.g., beavers, moles, and foxes. The sex and age of interviewees are related to these opinions. Most interviewees (39%) think that flooding was a result of embankment (dyke) instability. The spatial distribution of the survey results are analyzed. Maps presenting: inundation height, economic loss, attitude to geohazards and perception of possible flood recurrence were drawn. Causes of the flood as viewed by local inhabitants and in the context of the riverine geological setting and its processes are discussed. Particular attention is paid to processes linking the levee breach location with specific geomorphic features of the Holocene floodplain. A wide perspective of fluvial geomorphology where erosive landforms of crevasse channels (and associated depositional crevasse splays) are indicators of geohazards was adopted. This distinct geomorphological imprint left by overbank flow is considered a natural flood mark. Such an approach is completely neglected by interviewees who overestimate the role of hydrotechnical structures.

یاسین صالحی, علیرضا واعظی

مقدمهفرسایش خاک یکی از عوامل تخریب اراضی و از مهم‌ترین معضلات ‌محیط زیست، کشاورزی و تولید غذا در جهان است. بیش از نیمی از مهم‌ترین اراضی کشاورزی در مناطق نیمه‌خشک، تحت کشت دیم هستند و تنش‌های ناشی از فرسایش و تخریب اراضی به‌صورت مستقیم از دو جهت، اثرات درون عرصه فرسایش همچون حاصلخیزی خاک و اثرات برون عرصه‌ای مانند آلودگی خاک، حائز اهمیت است. شناخت توزیع اندازه ذرات فرسایش یافته، گام اساسی برای مدیریت هدررفت عناصر غذایی و انتقال آلاینده‌ها از خاک است. برای این منظور، این پژوهش با هدف بررسی توزیع اندازه رسوبات حاصل از فرسایش بین شیاری تحت تاثیر درجه شیب و بافت خاک در برخی خاک‌های منطقه نیمه‌خشک زنجان، انجام شد. مواد و روش‌هابرای انجام این پژوهش، چهار دامنه دارای خاک با بافت مختلف (لوم شنی، لوم سیلتی، لوم رس شنی و لوم رسی) در چهار اندازه شیب شمال به جنوب (پنج، 10، 15 و 20 درصد) با استفاده از باران شبیه‌سازی شده، با شدت 60 میلی‌متر بر ساعت به مدت 60 دقیقه، مورد بررسی قرار گرفت. رواناب و رسوب در بازه‌های زمانی پنج دقیقه از آغاز رواناب تا رسیدن به حالت پایدار، در ظرف‌های مدرج مجزا جمع‌آوری و حجم و وزن آن اندازه‌گیری شد. توزیع اندازه ذرات رسوب به روش جداسازی ذرات با استفاده از سری الک‌های به قطر 75، دو، یک، 0.5، 0.25، 0.1 و 0.05 میلی‌متر تعیین شد. همچنین، درصد ذرات ریزتر (سیلت و رس) از روش هیدرومتر محاسبه شد. سپس، ذرات رسوب در هشت دسته شامل سنگریزه (دو تا 75 میلی‌متر)، شن بسیار درشت (یک تا دو میلی‌متر)، شن درشت (0.5 تا یک میلی‌متر)، شن متوسط (0.5-0.25 میلی‌متر)، شن ریز (0.25-0.1 میلی‌متر)، شن بسیار ریز (0.1-0.05)، سیلت (0.05-0.002 میلی‌متر) و رس (0.002 > میلی‌متر) دسته‌بندی شدند. نتایج و بحثنتایج نشان داد، با افزایش شیب سطح زمین، توزیع اندازه ذرات رسوب در همه خاک‌ها دچار تغییر شد. به‌طوری که انتقال ذرات درشت‌تر از 0.1 میلی‌متر (شامل شن بسیار درشت، شن درشت، شن متوسط و شن ریز) با افزایش شیب بیشتر می‌شود. در حالی‌ که درصد ذرات سیلت (از 0.002 تا 0.05 میلی‌متر) در همه بافت‌ها کاهش یافت. همچنین، ذرات در طبقه اندازه شن متوسط و شن ریز که بین 40 تا 50 درصد ذرات رسوب برای هر بافت را تشکیل دادند، با افزایش شیب، تغییر معنی‌داری نداشتند. بیشترین نسبت ذرات در رسوب به خاک اصلی، مربوط به ذرات سیلت در بافت لوم سیلتی (4.33 برابر) و کمترین آن نیز مربوط به ذرات رس در بافت لوم سیلتی (0.26 برابر) بود. ذرات شن و سیلت در بافت‌های مختلف، دارای نسبت‌های انتقال بالایی بودند. ذرات سیلت در سه بافت لوم شنی، لوم رسی و لوم سیلتی دارای نسبت بیش از یک و ذرات رس دارای نسبت کمتر از یک بودند. ذرات شن نیز به جز در بافت لوم رسی، در بیشتر بافت‌ها در محدوده 0.83 تا 1.24 برابر نسبت به خاک اصلی تغییر کرد و میانگین کلی نسبت فراهمی آن در رسوب به خاک اصلی، 0.98 برابر بود. نتیجه‌گیریبه‌طور کلی، این پژوهش نشان داد با افزایش شیب، سطح انتخاب‌پذیری ذرات ریز کاهش و سهم ذرات درشت افزایش می‌یابد. اثرگذاری این تغییرات در خاک‌های ریزبافت بیشتر خود را نمایان می‌کند. با توجه به افزایش تخریب خاکدانه‌ها و شدت جریان با افزایش شیب سطح، جلوگیری از حذف پوشش گیاهی و رعایت اصول خاک‌ورزی در جهت کاهش برخورد مستقیم قطرات باران بر سطح خاک و کاهش انتقال‌پذیری ذرات به‌وسیله جریان بسیار با اهمیت است. همچنین، نتایج نشان می‌دهد که نسبت ذرات در بافت خاک و خصوصیات ساختمان خاک (فراوانی و پایداری خاکدانه‌ها)، از عوامل تعیین‌کننده انتقال ذرات بوده‌اند و در نظر گرفتن این ویژگی‌ها در انتخاب روش‌های حفاظت خاک، ضروری است.

Sifat Sarwar, Alistair G. L. Borthwick

Abstract The Ganges‐Brahmaputra‐Meghna delta is vulnerable to sea level rise from global warming. Based on sea level rise predictions for the year 2100 given in the 6th Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), we examine the effect of uncertainty in sea level rise on maximum tidal elevation statistics at several locations along the Bangladesh coastline using a discretized derived distribution approach. For five IPCC scenarios, the standard deviation in maximum tidal elevation including sea level rise is predicted to increase by between 3% and 61% at three different locations for a 41% increase in the standard deviation of mean sea level rise. By excluding the linear effect of sea level rise, the increase in the standard deviation of maximum tidal elevation is found to vary spatially from 2% to 68% with a 41% increase in the standard deviation of sea level rise.

Joao Leonardo Silva Cotta, Omar Qasem, Paula do Vale Pereira et al.

The growing number of noncooperative flying objects has prompted interest in sample-return and space debris removal missions. Current solutions are both costly and largely dependent on specific object identification and capture methods. In this paper, a low-cost modular approach for control of a swarm flight of small satellites in rendezvous and capture missions is proposed by solving the optimal output regulation problem. By integrating the theories of tracking control, adaptive optimal control, and output regulation, the optimal control policy is designed as a feedback-feedforward controller to guarantee the asymptotic tracking of a class of reference input generated by the leader. The estimated state vector of the space object of interest and communication within satellites is assumed to be available. The controller rejects the nonvanishing disturbances injected into the follower satellite while maintaining the closed-loop stability of the overall leader-follower system. The simulation results under the Basilisk-ROS2 framework environment for high-fidelity space applications with accurate spacecraft dynamics, are compared with those from a classical linear quadratic regulator controller, and the results reveal the efficiency and practicality of the proposed method.

Jietian Liu, Peter Seiler

This paper presents a synthesis method for robust, regret optimal control. The plant is modeled in discrete-time by an uncertain linear time-invariant (LTI) system. An optimal non-causal controller is constructed using the nominal plant model and given full knowledge of the disturbance. Robust regret is defined relative to the performance of this optimal non-causal control. It is shown that a controller achieves robust regret if and only if it satisfies a robust $H_\infty$ performance condition. DK-iteration can be used to synthesize a controller that satisfies this condition and hence achieve a given level of robust regret. The approach is demonstrated three examples: (i) a simple single-input, single-output classical design, (ii) a longitudinal control for a simplified model for a Boeing 747 model, and (iii) an active suspension for a quarter car model. All examples compare the robust regret optimal against regret optimal controllers designed without uncertainty.

Yaashia Gautam, Marco M. Nicotra

This paper introduces a new framework for analyzing the stability of discrete-time model predictive controllers acting on continuous-time systems. The proposed framework introduces the distinction between discretization time (used to generate the optimal control problem) and sampling time (used to implement the controller). The paper not only shows that these two time constants are independent, but also motivates the benefits of selecting a sampling time that is smaller than the discretization time. The resulting approach, hereafter referred to as Hypersampled Model Predictive Control, overcomes the traditional trade-off between performance and computational complexity that arises when selecting the sampling time of traditional discrete-time model predictive controllers.

Meixiu Yu, Xiaolong Liu, Paul Wood et al.

Abstract Due to an intensification of anthropogenic activities and climate change in recent decades, the hydrological connections and relationships between rivers and lakes have been significantly modified globally. Poyang Lake is one of the largest freshwater lakes globally and is one of the few that remain naturally connected to the Yangtze River. To investigate the full hydrological conditions (extreme high and low discharge) of Poyang Lake outflow under current bathymetric conditions, a large‐scale 1D‐ and 2D‐coupled high‐resolution hydrodynamic model of the Poyang Lake basin–Yangtze River system was developed. We simulated the outflow and water levels of Poyang Lake under nine different extreme hydrological scenarios with high precision and computational efficiency. We propose (1) a novel partition calibration method to characterize the roughness coefficient of large water bodies in complicated geographical terrain both for wet and dry seasons; (2) a new method for setting initial conditions for hydrodynamic simulation of large water bodies subject to strong hydrological regulation. Results indicated that (1) maximum outflow and water levels will reach 37,200 m3/s and 22.28 m when Poyang Lake basin floodwater coincides with flooding on the Yangtze River; (2) precipitation over the lake has increased outflow but this has had very limited influence on its changing hydrological pattern; (3) the effect of hydrological conditions within the system differs for both the lake outflow and water level. The research provides important reference conditions for the application of the InfoWorks ICM model in future applications and studies of large river–lake systems.

Lintao Ye, Ming Chi, Zhi-Wei Liu et al.

We study the simultaneous actuator selection and controller design problem for linear quadratic regulation with Gaussian noise over a finite horizon of length $T$ and unknown system model. We consider both episodic and non-episodic settings of the problem and propose online algorithms that specify both the sets of actuators to be utilized under a cardinality constraint and the controls corresponding to the sets of selected actuators. In the episodic setting, the interaction with the system breaks into $N$ episodes, each of which restarts from a given initial condition and has length $T$. In the non-episodic setting, the interaction goes on continuously. Our online algorithms leverage a multiarmed bandit algorithm to select the sets of actuators and a certainty equivalence approach to design the corresponding controls. We show that our online algorithms yield $\sqrt{N}$-regret for the episodic setting and $T^{2/3}$-regret for the non-episodic setting. We extend our algorithm design and analysis to show scalability with respect to both the total number of candidate actuators and the cardinality constraint. We numerically validate our theoretical results.