QC-SANE: Robust Control in DRL using Quantile Critic with Spiking Actor and Normalized Ensemble

Recently Introduced Deep Reinforcement Learning (DRL) Techniques in Discrete-Time Have Resulted in Significant Advances in Online Games, Robotics, and So On. Inspired from Recent Developments, We Have Proposed an Approach Referred to as Quantile Critic with Spiking Actor and Normalized Ensemble (QC-SANE) for Continuous Control Problems, Which Uses Quantile Loss to Train Critic and a Spiking Neural Network (NN) to Train an Ensemble of Actors. the NN Does an Internal Normalization using a Scaled Exponential Linear Unit (SELU) Activation Function and Ensures Robustness. the Empirical Study on Multijoint Dynamics with Contact (MuJoCo)-Based Environments Shows Improved Training and Test Results Than the State-Of-The-Art Approach: Population Coded Spiking Actor Network (PopSAN)

Unintended consequences: Why carbonation can dominate in microscale hydration of calcium silicates

The initial microscale mechanisms and materials interfacial process responsible for hydration of calcium silicates are poorly understood even in model systems. The lack of a measured microscale chemical signature has confounded understanding of growth mechanisms and kinetics for microreaction volumes. Here, we use Raman and optical spectroscopies to quantify hydration and environmental carbonation of tricalcium silicates across length and time scales. We show via spatially resolved chemical analysis that carbonate formation during the initial byproduct in microscale reaction volumes is significant, even for subambient CO2 levels. We propose that the competition between carbonation and hydration is enhanced strongly in microscale reaction volumes by increased surface-to-volume ratio relative to macroscale volumes, and by increased concentration of dissolved Ca2+ ions under poor hydration conditions that promote evaporation. This in situ analysis provides the first direct correlation between microscale interfacial hydration and carbonation environments and chemically defined reaction products in cementitious materials.United States. Department of Homeland Security. Science and Technology DirectorateMIT Concrete Sustainability HubPortland Cement AssociationReady Mixed Concrete (RMC) Research & Education Foundatio

NK-CD11c+ Cell Crosstalk in Diabetes Enhances IL-6-Mediated Inflammation during Mycobacterium tuberculosis Infection

In this study, we developed a mouse model of type 2 diabetes mellitus (T2DM) using streptozotocin and nicotinamide and identified factors that increase susceptibility of T2DM mice to infection by Mycobacterium tuberculosis (Mtb). All Mtb-infected T2DM mice and 40% of uninfected T2DM mice died within 10 months, whereas all control mice survived. In Mtb-infected mice, T2DM increased the bacterial burden and pro- and anti-inflammatory cytokine and chemokine production in the lungs relative to those in uninfected T2DM mice and infected control mice. Levels of IL-6 also increased. Anti-IL-6 monoclonal antibody treatment of Mtb-infected acute- and chronic-T2DM mice increased survival (to 100%) and reduced pro- and anti-inflammatory cytokine expression. CD11c+ cells were the major source of IL-6 in Mtb-infected T2DM mice. Pulmonary natural killer (NK) cells in Mtb-infected T2DM mice further increased IL-6 production by autologous CD11c+ cells through their activating receptors. Anti-NK1.1 antibody treatment of Mtb-infected acute-T2DM mice increased survival and reduced pro- and anti-inflammatory cytokine expression. Furthermore, IL-6 increased inflammatory cytokine production by T lymphocytes in pulmonary tuberculosis patients with T2DM. Overall, the results suggest that NK-CD11c+ cell interactions increase IL-6 production, which in turn drives the pathological immune response and mortality associated with Mtb infection in diabetic mice

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Calcium-Silicate-Hydrate in cementitious systems : chemomechanical correlations, extreme temperature behavior, and kinetics and morphology of in-situ formation

Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 96-102).Concrete, the second most used material on the planet, is a multi-scale heterogeneous material. A fundamental component known as Calcium-Silicate-Hydrate which forms from the reaction between cement and water is the binding phase in concrete. Curiously, this is the least understood component of concrete because of its porous amorphous structure. Further, beyond mere scientific curiosity, cementS̆s industry large carbon footprint due to its volume of usage sets up a practical context to seek improvements in concrete performance and equip concrete with additional functionalities. It is our contention that we can better understand the least known and crucial component of concrete, Calcium-Silicate-Hydrate, to inform the design of next generation of high performance concrete. With this broad theme, this thesis presents three different aspects of properties of Calcium Silicate Hydrate: chemomechanical correlations, behavior under extreme temperature and pressures, and kinetics and nanostructure of in-situ formation. Calcium Silicate Hydrate (C-S-H) formed in-situ in concrete is believed to have a layered structure with silicate chains similar to crystal structures of Tobermorite and Jennite. Its chemical composition, characterized by Ca/Si ratio, must therefore influence its silicate chain structure and thus its mechanical properties. We explore the correlation between CS- H composition and its mechanical properties. By varying chemical composition of cement clinkers and supplementary cementitious materials, water/cement ratios, and hydration temperatures, we prepare cement pastes with different C-S-H of different C/S ratios. We use nanoindentation and X-ray spectroscopy to respectively measure the mechanical properties and composition of C-S-H. We then study the mechanical performance of C-S-H at elevated temperatures. This is relevant in the design of infrastructure that can sustain extreme events such as blasts and high velocity impacts. As a starting point for concrete that would enable such infrastructure, we use ultra high performance concrete (UHPC). We use nanoindentation and X-ray spectroscopy to respectively measure mechanical properties and composition of individual components of UHPC. We compare the composition and properties of C-S-H found in UHPC to that found in ordinary cement pastes (OPC). Our grid nanoindentation experiments also reveal an artifacts created by the incorporation of steel fiber reinforcements in UHPC. We find that steel fiber reinforcements disrupt the perfect packing of constituent materials in UHPC to create capillary porosity at microscale. Further, we study the mechanical properties of C-S-H in concrete specimens subjected to high temperatures of 400°C and 1000°C. As a product of the reaction between cement and water, the properties of C-S-H are ultimately controlled by the reaction. To obtain quantitative kinetics, we use time-lapse optical microscopy to study hydration of micron sized monoclinic C₃S particles with in droplets of water of 50 [mu]m. Using Raman spectroscopy, we characterize the hydration product growing inside these droplets.by Deepak Jagannathan.S.M

Real-time Detection of Grip Length Deviation during Pull-type Fastening: A Mahalanobis-Taguchi System (MTS)-based Approach

In this study, a Mahalanobis-Taguchi system (MTS)-based diagnostic and root cause analysis scheme for monitoring grip length of pull-type fasteners in real-time is presented. The proposed approach is implemented on a fastening tool integrated with a strain gage, a linear variable differential transformer, a pressure sensor, and a mote for wireless communication. Experiments show that the process signature of strain-over-displacement ratio versus displacement has unique features that can be used to determine the grip length related deviations. The proposed approach takes as input various characteristics, such as peak strain, peak displacement, and depth and width of a bowl-shaped dip on the process signature in order to make real-time decisions. The experiments show that the proposed approach is effective in determining grip length deviations and in communicating the decision in real-time via a wireless network to a base station. Overall, the proposed architecture has merits to (1) detect quality problems in real-time during the fastening process and (2) reduce post-process inspection, thereby improving quality while reducing cost. In addition, the approach facilitates 100% data collection on each fastener as opposed to traditional statistical process control (SPC) techniques, which rely on sampling

Real-time Detection of Grip Length during Fastening of Bolted Joints: A Mahalanobis-Taguchi System (MTS) Based Approach

This paper presents a Mahalanobis-Taguchi System (MTS) based methodology that detects grip length of bolted joints in real-time during fastening. Grip length is the length of the unthreaded portion of a bolt shaft. when the total thickness of joining members is greater than the grip length of the bolt, it is called under-grip, which compromises the structural integrity of a joint. In this study, a pneumatic, hand-held, rotary-type tool for bolted joints is integrated with a torque sensor and an optical encoder in order to obtain torque-angle signatures. Then, the signature is processed in real-time using the MTS-based approach in order to detect the grip-length, all of which occurs in real-time as the fastening process is completed. The proposed approach is also applied to detect the presence of re-used fasteners, which is another quality concern since some material properties and physical conditions of bolts and nuts can change if they are reused several times. The proposed approach reads in various characteristics from the torque-angle process signature, including mean and standard deviation of the torque-over-angle and angle-over-torque ratios, total angle turned, and work done during the different stages of the fastening process in order to infer about the quality of the bolted joint. The experimental results show that the proposed approach is successful with an accuracy of over 95% in detecting various grip lengths and presence of re-used fasteners

Real-Time Process Quality Monitoring using Wireless Sensor-Embedded Rotary Tools for Fastening Operations

Fastening operations are extensively used in the aerospace industry and constitute for more than a quarter of the total cost. Inspection of fasteners is another factor that adds cost and complexity to the overall process. Inspection is usually carried out on a sampling-basis as a stand-alone process after the fastening process is completed. Lack of capability to inspect all fasteners in a cost effective manner and the need to remove non-value added activities, such as inspection by itself, in order to reduce the manufacturing lead time have been the motivation behind this study. This paper presents a novel diagnostics scheme based on Mahalanobis-Taguchi System (MTS) for monitoring the quality of rotary-type fastening operations in real-time. This approach encompasses (1) integrating a torque sensor, a pressure sensor, and an optical encoder on a hand-held rotary-type fastening tool; (2) obtaining process parameters via the embedded sensors and generating process signatures in real-time; and (3) detecting anomalies on the tool using a wireless mote that communicates the decision with a base station. the anomalies investigated in this study are the grip length variations as under grip and normal grip, and presence of re-used fasteners. the proposed scheme has been implemented on prototype rotary tool for bolt-nut type of fasteners and tested under a variety of experimental settings. the experimental results have shown that the proposed approach is successful, with an accuracy of over 95% in detecting grip lengths of fasteners in real-time during the proces