Recent Results Research Articles

Continuous-Time Reinforcement Learning Control: A Review of Theoretical Results, Insights on Performance, and Needs for New Designs.

This exposition discusses continuous-time reinforcement learning (CT-RL) for the control of affine nonlinear systems. We review four seminal methods that are the centerpieces of the most recent results on CT-RL control. We survey the theoretical results of the four methods, highlighting their fundamental importance and successes by including discussions on problem formulation, key assumptions, algorithm procedures, and theoretical guarantees. Subsequently, we evaluate the performance of the control designs to provide analyses and insights on the feasibility of these design methods for applications from a control designer's point of view. Through systematic evaluations, we point out when theory diverges from practical controller synthesis. We, furthermore, introduce a new quantitative analytical framework to diagnose the observed discrepancies. Based on the analyses and the insights gained through quantitative evaluations, we point out potential future research directions to unleash the potential of CT-RL control algorithms in addressing the identified challenges.

Preface

Abstract In the midst of the rapidly evolving landscape of technological advancements, the field of mechanical instrumentation and automation has emerged as a pivotal cornerstone in driving industrial progress and scientific exploration. It is with this recognition that we gathered once again for the 2024 5th International Conference on Mechanical Instrumentation and Automation (ICMIA 2024), a forum that aims to showcase the latest research achievements, foster collaborations, and pave the way for innovative solutions in this dynamic domain. The ICMIA 2024, held in Wuhan, China, from April 19th to 21st, 2024 via hybrid form, serves as a gathering place for experts, scholars, researchers, and practitioners from around the world. It provides a unique platform to share insights, discuss challenges, and explore opportunities in the field of mechanical instrumentation and automation. This conference serves not only as a showcase for the latest research but also as a catalyst for cross-disciplinary collaborations and knowledge exchange. The keynote speakers at ICMIA 2024 brought with them a wealth of experience and expertise. Their presentations, focusing on cutting-edge research and industry applications, provided valuable insights into the current state of the art and future directions of mechanical instrumentation and automation. Among them, Prof. Ning Sun (Nankai University, China) made a speech on Intelligent Control for Complex Underactuated Cranes with Applications. He first shared some of his team’s recent results on dynamics analysis, motion planning, and intelligent control of different crane systems, and then discussed some of their extended and related researches on robotic systems with similar dynamic characteristics. We are grateful to these esteemed speakers for sharing their knowledge and insights. The collected papers in this volume represent the culmination of rigorous research and innovative ideas presented at ICMIA 2024. These papers span a wide range of topics, including but not limited to Mechanical and Instrument Design, Instrument Science and Technology, Electronic Design Automation, Fault Diagnosis and Maintenance Theory, Automatic Detection and Instrumentation, Intelligent Instrument System, and their applications in various industrial sectors. The authors, representing a diverse array of backgrounds and institutions, have contributed their valuable research to this volume, reflecting the global reach and impact of the conference. The selection process for these papers was rigorous and thorough. All submitted papers were subjected to peer review by experts in the field, ensuring the highest standards of quality and relevance. The accepted papers were then carefully curated and compiled into this volume, providing a comprehensive overview of the latest advancements in mechanical instrumentation and automation. We are proud to present this collection of papers as a testament to the excellence and vibrancy of the research community in this field. We hope that this volume will serve as a valuable resource for researchers, practitioners, and students alike, inspiring new ideas, fostering collaborations, and propelling the field of mechanical instrumentation and automation forward. List of Committee Member is available in this Pdf.

Rare events in extreme value statistics of jump processes with power tails.

We study rare events in the extreme value statistics of stochastic symmetric jump processes with power tails in the distributions of the jumps, using the big -jump principle. The principle states that in the presence of stochastic processes with power tails statistics, if at a certain time a physical quantity takes on a value much larger than its typical value, this large fluctuation is realized through a single macroscopic jump that exceeds the typical scale of the process by several orders of magnitude. In particular, our estimation focuses on the asymptotic behavior of the tail of the probability distribution of maxima, a fundamental quantity in a wide class of stochastic models used in chemistry to estimate reaction thresholds, in climatology for earthquake risk assessment, in finance for portfolio management, and in ecology for the collective behavior of species. We determine the analytical form of the probability distribution of rare events in the extreme value statistics of three jump processes with power tails: Lévy flights, Lévy walks, and the Lévy-Lorentz gas. For the Lévy flights, we re-obtain through the big-jump approach recent analytical results, extending their validity. For the Lévy-Lorentz gas, we show that the topology of the disordered lattice along which the walker moves induces memory effects in its dynamics, which influences the extreme value statistics. Our results are confirmed by extensive numerical simulations.

Design and characterization of the time-resolved opacity spectrometer (OpSpecTR) for the NIF iron opacity campaign.

A new time-resolved opacity spectrometer (OpSpecTR) is currently under development for the National Ignition Facility (NIF) opacity campaign. The spectrometer utilizes Icarus version 2 (IV2) hybridized complementary metal-oxide-semiconductor sensors to collect gated data at the time of the opacity transmission signal, unlocking the ability to collect higher-temperature measurements on NIF. Experimental conditions to achieve higher temperatures are feasible; however, backgrounds will dominate the data collected by the current time-integrating opacity spectrometer. The shortest available OpSpecTR integration time of ∼2ns is predicted to reduce self-emission and other late-time backgrounds by up to 80%. Initially, three Icarus sensors will be used to collect data in the self-emission, backlighter, and absorption regions of the transmission spectrum, with plans to upgrade to five Daedalus sensors in future implementations with integration times of ∼1.3ns. We present the details of the diagnostic design along with recent characterization results of the IV2 sensors.

Current Landscape of Antibody-Drug Conjugate Development in Head and Neck Cancer.

Antibody-drug conjugates (ADCs) are fusions of therapeutic drugs and antibodies conjugated by a linker, designed to deliver a therapeutic payload to cells expressing the target antigen. By delivering the highly cytotoxic agent directly to cancer cells, ADCs are designed to enhance safety and broaden the therapeutic window. Recently, ADCs have demonstrated promising efficacy in various solid tumors and are rapidly expanding their indications. The prognosis of patients with advanced head and neck squamous cell carcinoma (HNSCC) remains poor, with no new therapeutics since the advent of anti-PD-1 antibodies in 2016, highlighting a critical need for innovative therapies. Recent preliminary results suggest that ADCs could be promising treatment options for HNSCC as they explore a variety of target antigens, payloads, and linkers. However, for successful adaptation of ADCs in the treatment of HNSCC, addressing key challenges such as payload toxicities, antigen heterogeneity, and adaptive resistance will be essential. Current research focused on new ADC structures, including multispecific antibodies and noncytotoxic payloads, and diverse combination approaches, show promise for future advancements.

Diabetes‐related distress in people with type 2 diabetes: experience from a community diabetes clinic

AbstractBackground: Diabetes distress is the term used to describe the diabetes‐specific emotional distress resulting from the challenges of managing this demanding chronic condition.Aims: This study aimed to determine the prevalence of diabetes distress and its subtypes in adults with type 2 diabetes who attended our community‐based clinics and to investigate the relationship between diabetes distress scores and demographic factors and diabetes variables (HbA1c and treatment regimen).Methods: Patients were referred to our specialist diabetes team by primary care teams. Clinical details, including current treatment regimen and recent HbA1c result, were recorded. Patients then completed the Diabetes Distress Scale (DDS) 17 questionnaire. Data from all 82 patients who attended our clinic from May 2022 to November 2022 were analysed.Results: A high level of diabetes distress (mean score of ≥3) was found in 17 patients (20.7%), and a moderate level of diabetes distress was found in 22 patients (26.8%). Patients with an HbA1c of >90mmol/mol had significantly higher mean regimen‐related distress than those with an HbA1c of <60mmol/mol (2.58±1.18 vs 1.86±0.8, respectively; p=0.03). In addition, patients with higher HbA1c had higher diabetes‐related emotional distress than those with lower HbA1c. However, this result did not demonstrate statistical significance. Conversely, patients with optimal HbA1c levels had significantly lower mean interpersonal distress scores than the rest of the cohort (1.13±0.99 vs 1.80±0.99, respectively; p=0.01).Conclusions: Diabetes distress is common among patients attending community‐based diabetes services. Further research is needed to determine the most effective strategies for reducing diabetes distress and improving clinical outcomes.

Causal sets and an emerging continuum

Causal set theory offers a simple and elegant picture of discrete physics. But the vast majority of causal sets look nothing at all like continuum spacetimes, and must be excluded in some way to obtain a realistic theory. I describe recent results showing that almost all non-manifoldlike causal sets are, in fact, very strongly suppressed in the gravitational path integral. This does not quite demonstrate the emergence of a continuum—we do not yet understand the remaining unsuppressed causal sets well enough—but it is a significant step in that direction.

Micro Solvation Effect of Methanol on Excited-State Dynamics of Protonated Tryptophan and Dopamine.

The electronic and vibrational cryogenic ion spectroscopy of protonated tryptophan (TrpH+) and dopamine (DAH+) complexed with methanol has been recorded. These two biological chromophores exhibit ultrafast photochemistry due to excited-state proton transfer (ESPT). We have established the relationship between the structure of the complexes and their photodynamics and compared them with recent results obtained in hydrated complexes. For TrpH+, there is no substantial change between methanol and water complexes; ESPT is hindered by a single solvent molecule. In the DAH+(MeOH)1 complex, the most stable conformer adopts a structure that prevents the direct interaction of the ammonium group of the side chain with the catechol ring, thus blocking the ESPT reaction. Such a ring structure is indeed a very minor populated conformer in the single-hydrated complex. The change in conformal stability between water and methanol clusters is due to a weak CH-π attractive interaction of the methyl group of methanol with the catechol.

GUT AND SKIN MICROBIOME IN PATIENTS WITH HIDRADENITIS SUPPURATIVA

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease that profoundly diminishes the quality of life for the affected patients, and is characterized by persistent purulent lesions in anatomical areas prone to constant skin friction, such as the armpits, groin, buttocks and breasts. The HS pathophysiology encompasses an array of factors, such as inflammation, genetics, the microbiome of the patient, and environmental components to name a few. Although it has been implicated that the patient microbiome is one of the factors in the pathogenesis of HS, the precise connection between the commensals and the host still remains to be fully researched. The studies examined in this review note that Porphyromonas, Peptoniphilus and Prevotella spp were observed in the skin microbiome of the patients with hidradenitis suppurativa, along with the decrease in Cutibacterium. The increase of certain bacterial species, such as Robinsoniella peoriensis, Bilophila, Holdemania, and Ruminococcus callidus was also observed when comparing gut microbiomes of the healthy subjects to those with hidradenitis suppurativa, suggesting that these microorganisms may be involved in the pathophysiology of HS. However, the specific mechanisms that regulate the interaction between the gut and skin microorganisms remain unclear. Therefore, the purpose of this review is to analyze the recent results from skin and microbiome studies related to hidradenitis suppurativa.

Vanishing of Long Time average p-enstrophy Dissipation Rate in the Inviscid Limit of the 2D Damped Navier–Stokes Equations

In Constantin and Ramos (Commun Math Phys 275(2), 529–551, 2007), Constantin and Ramos proved a result on the vanishing long time average enstrophy dissipation rate in the inviscid limit of the 2D damped Navier–Stokes equations. In this work, we prove a generalization of this for the p-enstrophy, 1<p<∞\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1< p < \\infty $$\\end{document}, sequences of distributions of initial data and sequences of strongly converging right-hand sides. We simplify their approach by working with invariant measures on the global attractors which can be characterized via bounded complete solution trajectories. Then, working on the level of trajectories allows us to directly employ some recent results on strong convergence of the vorticity in the inviscid limit.

On the Liouville function at polynomial arguments

abstract: Let $\lambda$ denote the Liouville function. A problem posed by Chowla and by Cassaigne--Ferenczi--Mauduit--Rivat--S\'ark\"ozy asks to show that if $P(x)\in\mathbb{Z}[x]$, then the sequence $\lambda(P(n))$ changes sign infinitely often, assuming only that $P(x)$ is not the square of another polynomial. We show that the sequence $\lambda(P(n))$ indeed changes sign infinitely often, provided that either (i) $P$ factorizes into linear factors over the rationals; or (ii) $P$ is a reducible cubic polynomial; or (iii) $P$ factorizes into a product of any number of quadratics of a certain type; or (iv) $P$ is any polynomial not belonging to an exceptional set of density zero. Concerning (i), we prove more generally that the partial sums of $g(P(n))$ for $g$ a bounded multiplicative function exhibit nontrivial cancellation under necessary and sufficient conditions on $g$. This establishes a ``99\% version'' of Elliott's conjecture for multiplicative functions taking values in the roots of unity of some order. Part (iv) also generalizes to the setting of $g(P(n))$ and provides a multiplicative function analogue of a recent result of Skorobogatov and Sofos on almost all polynomials attaining a prime value.

Ground-based gamma-ray astronomy: status and future

In this video article the author covers the history and current status of ground-based gamma-ray astronomy. The recent results in this field have brought important implications to various aspects in astrophysics, such as cosmic ray science and black holes and dark matters, and thus advanced our understanding of the dynamic non-thermal universe. The author also discusses the future prospects in this field, especially the possible imaging air Cherenkov telescopes in GeV energy range.

Recent results in the study of the 20Ne + 130Te collision within the NUMEN project and future perspectives

Recent results in the study of the 20Ne + 130Te collision within the NUMEN project and future perspectives

Recent results on elastic scattering and single-neutron stripping reaction in the 18O+48Ti collision at 275 MeV

Recent results on elastic scattering and single-neutron stripping reaction in the 18O+48Ti collision at 275 MeV

Energy equality of weak solutions of the 2D reduced‐gravity two‐and‐a‐half layer system allowing vacuum

The energy conservation problem for the reduced‐gravity two‐and‐a‐half layer model remains a challenging open problem, with several recent contributions addressing various aspects of it. In this paper, we establish sufficient conditions on the regularity of weak solutions that guarantee energy conservation even in the presence of a vacuum. Our theorem corresponds to an improvement of some recent results on this problem and contains some well‐known results as a particular case.

Higher order moments for SPDE with monotone nonlinearities*

This paper introduces a new p-dependent coercivity condition through which L p -moments for solutions can be obtained for a large class of SPDEs in the variational framework. If p = 2, our condition reduces to the classical coercivity condition, which only yields second moments for the solution. The abstract result is shown to be optimal. Moreover, the results are applied to obtain L p -moments of solutions for several classical SPDEs such as stochastic heat equations with Dirichlet and Neumann boundary conditions, Burgers' equation and the Navier–Stokes equations in two spatial dimensions. Furthermore, we can recover recent results for systems of SPDEs and higher-order SPDEs using our unifying coercivity condition.

Matching cities by their climate change measures and blockages profile for mutual-learning.

More and more cities are working on climate resilience by adding climate adaptive measures to their mitigation programs, but choices must be made and barriers must be overcome, as shown by the extensive research in this area, including our own previously conducted exploratory research (Sanders &amp; Oliveira, 2020). The motivation for new follow-up research has been to develop an instrument with which cities can compare each other’s climate programs, to find the right city partner to start a process of joint learning from each other. After studying current research classifying cities' climate adaptive measures, implemented or in planning, most research is into processes to help cities find the right measures, it has been concluded that the level of detail on which this research generally focuses is too detailed to help cities comparing to find their matching city partner. That is why it was ultimately decided to extent our own diagram from the aforementioned exploratory research, which is less abstract, with the aim of providing cities with this improved instrument. It should be noted that given the higher level of detail, we should speak of blockages rather than barriers. The recent results of the H2020 Marie Curie 'SOS Climate Waterfront' study were used to test this improved diagram, as data on climate adaptive measures from six European coastal cities recently became available. A test diagram was then generated for each of these cities and matching has been selected to evaluate the diagram, in order to make a well-functioning instrument available. The final conclusion is that the diagram provides a recognizable matching for the six SOS cities, but that improvement of the diagram is recommended during further use.

New insights into the role of nitrogen doping in microporous carbon on the capacitive charge storage mechanism: From ab initio to machine learning accelerated molecular dynamics

Fundamental understandings of the relationship between ion-electrode interaction and structural feature in porous carbon electrodes at a molecular level provides guidelines for the design of high-performance electric double layer supercapacitors. It is certified by experiments that porous carbon structures doped with nitrogen show enhanced capacitive performance. However, in the theoretical simulations, the fundamental charge storage mechanism is still elusive. In particular, the recent experimental result shows that the generally ignored nitrolic nitrogen (N5) in porous carbon exhibits a positive effect on capacitance, while graphitic nitrogen (N3) does the opposite, which is against with the simulation results based the 2D-modeled porous graphene structure. Here, we perform ab initio molecular dynamics simulations on the N3 and N5-doped carbon/electrolyte interfaces, including both 2D planar and 3D microporous carbon electrodes. Our calculation indicates that N3 in the 3D pore hinders the electrolyte transport, while N5-doped micropore still serves as an electrolyte transport channel through the formation of H-bond. The charge storage mechanism is further elucidated by the analysis of the well equilibrated interfaces obtained from the machine learning force field accelerated molecular dynamics. Our work provides a new insight into the effect of nitrogen doping in 3D porous carbon, which is exactly opposite to the 2D planar graphene. Therefore, we emphasize that differences in the electrochemical conditions of 2D planar and 3D microporous carbon electrodes should be fully considered when analyzing the effects of surface chemistry on charge storage mechanisms.

Neon tetra fish (Paracheirodon innesi) as farm-to-optical-table Bragg reflectors

Iridophore networks in the skin of neon tetra fish are investigated for use as biologically sourced, tunable, Bragg reflector arrays. This paper reports on a method for immediate and fast post-processing of tissue to modify the structural color of iridophores found in the lateral color stripe. Conditions for fixation, as well as the environment post-fixation to improve longevity of the structural color, are also presented. Recent results from attempts to further increase the lifetime of post-mortem iridophore color through infiltration and embedding in low-acid glycol methacrylate are also discussed.

Multifrequency Analysis of Favored Models for the Messier 87* Accretion Flow

The polarized images of the supermassive black hole Messier 87* (M87*) produced by the Event Horizon Telescope (EHT) provide a direct view of the near-horizon emission from a black hole accretion and jet system. The EHT theoretical analysis of the polarized M87* images compared thousands of snapshots from numerical models with a variety of spins, magnetization states, viewing inclinations, and electron energy distributions, and found a small subset consistent with the observed image. In this article, we examine two models favored by EHT analyses: a magnetically arrested disk with moderate retrograde spin and a magnetically arrested disk with high prograde spin. Both have electron distribution functions that lead to strong depolarization by cold electrons. We ray trace five snapshots from each model at 22, 43, 86, 230, 345, and 690 GHz to forecast future very long baseline interferometry (VLBI) observations and examine limitations in numerical models. We find that even at low frequencies where optical and Faraday rotation depths are large, approximately rotationally symmetric polarization persists, suggesting that shallow depths dominate the polarization signal. However, morphology and spectra suggest that the assumed thermal electron distribution is not adequate to describe emission from the jet. We find 86 GHz images show a ringlike shape determined by a combination of plasma and spacetime imprints, smaller in diameter than recent results from the Global mm-VLBI Array. We find that the photon ring becomes more apparent with increasing frequency, and is more apparent in the retrograde model, leading to large differences between models in asymmetry and polarization structure.