Biological Propulsion Systems for Ships and Underwater Vehicles

Regulations and performance requirements related to technology development on all modes of transport vehicles for reduced pollution and environmental impact have become more stringent. Greening of transport system has been recognized as an important factor concerning global warming and climate change. Thus environment-friendly technical solutions offering a reduction of noxious exhaust gases are in demand. Aquatic animals have good swimming and maneuvering capabilities and these observations have motivated research on fish-like propulsion for marine vehicles. The fish fin movements, used by fish for their locomotion and positioning, are being replicated by researchers as flapping foils to mimic the biological system. Studies show that flapping foil propulsion systems are generally more efficient than a conventional screw propeller, which suffers efficiency losses due to wake. The flapping foil propulsors usually do not cavitate and have less wake velocity variation. These aspects result in the reduction of noise and vibration. The present study will cover an overview of aquatic propulsion systems, numerical simulations of flapping foils and ship model self-propulsion experiments performed using flapping foil system, particle image velocimetry (PIV), and digital fluoroscopy studies conducted on fish locomotion. Studies performed on underwater and surface vehicles fitted with flapping fins will also be presented

Immune response and protection against Streptococcus pyogenes after vaccination with Lactococcus lactis that expresses conserved region of M6 protein

Most pathogens gain access to their host through mucosal surfaces. It is therefore desirable to develop mucosal vaccines that elicit an immune response to prevent this crucial first step in infection. Current mucosal vaccines are live attenuated strains of pathogens. More recent efforts have focused on the use of recombinant non-pathogenic gram-positive bacteria as live vaccine delivery vectors. Here I have tested the potential of Lactococcus lactis to be used as a vaccine vector. A recombinant strain of L. lactis has been constructed which expresses and displays on its surface the C repeat region (CRR) of the M6 protein of Streptococcus pyogenes. I show that nasal vaccination of mice with this strain elicited strong salivary IgA and serum lgG response. These responses protected mice against a nasal challenge with S. pyogenes. Subcutaneous vaccination with the same strain of L. lactis produced a strong serum lgG response, but no salivary lgA response. Subcutaneous vaccination did not protect the mice against nasal infections when the mice were challenged with S. pyogenes. The immune response and protection afforded by concomitant vaccination by both nasal and subcutaneous routes were better that that seen in nasal vaccination alone. This study shows that an effective vaccine against S. pyogenes is possible using L. lactis as a vaccine vector. It also opens up the potential of L. lactis to be used in the development of vaccines to other mucosal infections

Macrophages sense and kill bacteria through carbon monoxide-dependent inflammasome activation

Microbial clearance by eukaryotes relies on complex and coordinated processes that remain poorly understood. The gasotransmitter carbon monoxide (CO) is generated by the stress-responsive enzyme heme oxygenase-1 (HO-1, encoded by Hmox1), which is highly induced in macrophages in response to bacterial infection. HO-1 deficiency results in inadequate pathogen clearance, exaggerated tissue damage, and increased mortality. Here, we determined that macrophage-generated CO promotes ATP production and release by bacteria, which then activates the Nacht, LRR, and PYD domains-containing protein 3 (NALP3) inflammasome, intensifying bacterial killing. Bacterial killing defects in HO-1-deficient murine macrophages were restored by administration of CO. Moreover, increased CO levels enhanced the bacterial clearance capacity of human macrophages and WT murine macrophages. CO-dependent bacterial clearance required the NALP3 inflammasome, as CO did not increase bacterial killing in macrophages isolated from NALP3-deficient or caspase-1-deficient mice. IL-1β cleavage and secretion were impaired in HO-1-deficient macrophages, and CO-dependent processing of IL-1β required the presence of bacteria-derived ATP. We found that bacteria remained viable to generate and release ATP in response to CO. The ATP then bound to macrophage nucleotide P2 receptors, resulting in activation of the NALP3/IL-1β inflammasome to amplify bacterial phagocytosis by macrophages. Taken together, our results indicate that macrophage-derived CO permits efficient and coordinated regulation of the host innate response to invading microbes.NIH grants: (HL-071797, HL-076167, HL-106227), American Heart Association grants: (10SDG2640091 and NIH R21CA169904-01), Julie Henry Fund, Transplant Center of the BIDMC, FCT grants: (SFRH/BPD/25436/2005, PTDC/BIO/70815/2006, PTDC/BIA-BCM/101311/2008, PTDC/SAU-FCF/100762/2008), the European Community, 6th Framework grant LSH-2005-1.2.5-1 and ERC-2011-AdG, Howard Hughes Medical Institute

Determination of ADAS AEB Car to Car and Car to Pedestrian Scenarios for Autonomous Vehicles

The percentage of ADAS features installed in cars and trucks, which are getting increasingly popular, has significantly increased. Experimental and numerical simulations are necessary to validate ADAS functions and assure passengers' safety. Per Euro NCAP testing standards, numerical studies are carried out on the current ADAS functions. The Lane Keeping Assist System and ADAS features were considered using MATLAB and Simulink software. In the present study, ADAS development and qualification tests are studied concerning vulnerable road users (VRU), such as Car to Car driving and Car to Pedestrian scenarios. Different parameters are used to investigate the impacts of subject/global and ego vehicle conditions such as acceleration, deceleration, perceptual reaction time, gap acceptability, and stop/go choice to avoid collisions. The present methodology evaluates Time-To-Collision (TTC) for different car-to-car and Car-to-pedestrian scenarios at different vehicle velocities. This method of testing autonomous emergency braking (AEB) function for passenger vehicles results in collision mitigation and avoidance and reduces the number of accidents based on human errors. © 2022 IEEE

Influenza SIRS with minimal pneumonitis

While systemic inflammatory response syndrome (SIRS), is a known complication of severe influenza pneumonia, it has been reported very rarely in patients with minimal parenchymal lung disease. We here report a case of severe SIRS, anasarca and marked vascular phenomena with minimal or no pneumonitis. This case highlights that viruses, including influenza, may cause vascular dysregulation causing SIRS, even without substantial visceral organ involvement

Propulsive Performance of Tandem Flapping Wings for Autonomous Underwater Vehicles (Auvs) and Surface Ships

The application of tandem flapping foils propulsors to conventional aerial and underwater vehicles plays a most important role in the exploration of aerial and marine environments. The hydrodynamic study of fish schooling or birds flock when swimming/flying in fluid media and the application towards development of tandem flapping wing robots gaining more importance in the field of bioinspired vehicles. The advantages of tandem flapping wing configuration are improved thrust performance; maneuvering and less energy input as the downstream foils consumes less power compared to the single flapping foils. In thist study, the thrust of two flapping foils arranged in tandem mode subjected to pitching motion with different pitching amplitudes(AD), Strouhal numbers (StD), stream wise distance (S/c) and phase-lag (varphi) of foils are studied numerically using RANSE based CFD solver. This novel study mainly investigates the effects of Strouhal number and the dimensionless pitching amplitude on the thrust and efficiency of tandem foils. It is observed that the tandem foils generate higher efficiency at text{St}-{mathrm{D}}=0.2 and mathrm{A}-{mathrm{D}}= 0.7. At this condition, the effects of stream wise distance and phase-lag of tandem foils are also investigated. When varphi is constant and S/c changes from 0.109 to 1, the efficiency of the upstream foil decreases and the efficiency of downstream foil increases. When S/c is constant and varphi changes from 0° to 180°, upstream foil efficiency increases and downstream foil efficiency decreases with increase in phase-lag. When varphi is 90°, total efficiency of the two foils gets the maximum value. In general, when S/c is 1 and varphi is 90°, the tandem flapping foils get the maximum propulsive efficiency. For achieving this condition, pitching amplitude, frequency and increased phase lag between the two foils plays a significant role compared to the stream wise distance(S/c) between the tandem foils. © 2021 IEEE

Propulsive Performance and Optimum Configuration of Tandem Flapping Foils

The application of tandem flapping foil propulsors to conventional aerial and underwater vehicles plays the most important role in the exploration of aerial and marine environments. The hydrodynamic study of fish schooling or birds' flock when swimming/flying in fluid media and the application toward the development of tandem flapping wing robots is gaining more importance in the field of bioinspired vehicles. The advantages of tandem flapping wing configuration are improved thrust performance, maneuvering, and less energy input as the downstream foils consume less power compared to the single flapping foil. In this study, the thrust of two flapping foils arranged in the tandemmode subjected to pitching motion with different pitching amplitudes (A(D)), Strouhal numbers (St(D)), streamwise distance (S/c), and phase lag (phi) of foils is studied numerically using the reynolds-averaged navier-stokes equation (RANSE)-based computational fluid dynamics solver. This novel study mainly investigates the effects of Strouhal number and the dimensionless pitching amplitude on the thrust and efficiency of tandem foils. It is observed that the tandem foils generate higher efficiency at St(D) = 0.2. At this condition, the effects of streamwise distance and phase lag of tandem foils are also investigated. When. is constant and S/c changes from 0.109 to 1, the efficiency of the upstream foil decreases and the efficiency of downstream foil increases. When S/c is constant and phi changes from 0 degrees to 180 degrees, the efficiency of the upstream foil increases and the efficiency of the downstream foil decreases with an increase in phase lag. When phi is 90 degrees, the total efficiency of the two foils gets the maximum value. In general, when S/c is 1 and. is 90 degrees, the tandem flapping foils get themaximum propulsive efficiency. For achieving this condition, pitching amplitude, frequency, and increased phase lag between the two foils play a significant role compared to the streamwise distance (S/c) between the tandem foils

Hydrodynamic Analysis of Extra-Terrestrial Submarine in Lakes of Titan using CFD

Extra-terrestrial space exploration projects have been a matter of interest with many space agencies given the possibility of non - Earth life forms, life-nurturing environments, or the presence of valuable minerals within our solar system. The present study conducts an aerodynamic analysis on a submarine body capable of examining the extra-terrestrial seas of Titan, which is expected to harbor life forms using CFD. Computational Fluid Dynamics or CFD is used to analyze the aerodynamic properties of the submarine. The present case is set up by enabling the liquid properties like that of Titan's seas with submarine deeply submerged inside the lake moving at a velocity of 1 - 3 m/s. The average drag coefficient observed for the L/D ratios 10.8, 12.5, and 14.4 is 0.059, 0.067, and 0.072, respectively, for the assumed geometry when the submarine is submerged deep inside the seas. © 2021 IEEE

Powering Prediction of an Autonomous Campus Shuttle using CFD

Universities and colleges worldwide are being equipped with campus shuttles due to their large campus size. These generally are 6-To-8-seater vehicles to transport students around the campus. Academic spaces around the world are built as safe places for the academia of the institution. Due to high safety advantages, many universities are considering utilizing autonomous vehicles instead of manual driving. These autonomous vehicles require various LiDAR, Radar, ultrasonic sensors, and cameras to sense their surroundings. These sensors need to be placed externally due to a larger area to detect any incoming dangers. These sensors, due to their placement, may impact the airflow around the vehicle. The present paper discusses the change in flow characteristics of the vehicle, such as pressure, velocity, drag coefficient, and lift coefficient. The vehicle's drag coefficient is expected to reduce by 2.2%, and the lift coefficient is likely to decline by 23.7% compared to the case without the sensors. © 2021 IEEE