Flow Measurements in Turbulent Flow Fields with Magnetic Resonance Phase Velocity Mapping

Arterial stenosis (narrowing) is due to vascular disease that, if untreated, leads to death. The stenosis causes the development of complex flow which results in high energy losses and great forces between blood and tissue. Traditionally, turbulent flows lead to signal loss in magnetic resonance (MR) image acquisitions, resulting in loss of diagnostic information. With the advancement in MR hardware and software, some of the limitations of MR in turbulent flow fields may have been reduced or eliminated. This study evaluated the potential of MR phase velocity mapping (MRPVM), a clinical velocimetry technique, under turbulent flow conditions such as those developed in arterial stenosis. Specifically, the goal of this study was to determine how accurately MRPVM can quantify the flow rate in experimental models of arterial stenosis under a variety of flow conditions, ranging from laminar to turbulent. Three models were used: a non-occluded straight tube an occluded tube with a 75 area reduction stenosis and an occluded tube with a 94 area reduction stenosis. Flow experiments were conducted under steady-state flow conditions (flow rates of 1.4-10.4 L/min) inside a 1.5 Tesla whole-body clinical Siemens MR scanner. Of interest was to vary several imaging parameters which control the time of the acquisitions and the spatial resolution of the acquired images. Therefore, five different echo times (TE) (2.65-6.0 ms) and three different combinations of the field of view and matrix size, resulting in three different spatial resolutions, were studied. Axial MRPVM acquisitions were performed in all models upstream, at the throat, and downstream of the stenosis. The acquired phase images provided the velocity from which the flow rate was calculated. The MR-measured flow rates were compared with the true flow rates from rotameters to determine the accuracy of MRPVM. The results confirmed that MRPVM can measure the flow rate accurately under laminar flow conditions. In turbulent flow, the accuracy was reduced due to signal l

Characterization of ice adhesion strength over different surfaces pertinent to aircraft anti-/de-icing

Aircraft icing is widely recognized as a significant hazard to aircraft operations in cold weather. A number of anti-/de-icing systems have been developed recently for aircraft icing mitigation and protection, which can generally be classified into two categories: active and passive methods. While active methods rely on energy input from an external system for the anti-/de-icing operation, passive methods take advantage of the physical properties of the surfaces to prevent ice formation and accretion. While there is no known passive system that can completely eliminate ice formation over the protected surfaces, passive anti-/de-icing methods, especially icephobic surface coatings, have been proved to be very helpful to mitigate the problematic effects of icing for various icing related applications. In the present study, a comprehensive study was conducted to characterize ice adhesion strength over various surfaces by using a custom-built shear strength tester. The studied surfaces include recently developed functionalized surfaces like Slippery Liquid-Infused Porous Surfaces (SLIPS) and commercially-available surface coatings like Hydrobeadî, NeverWetî; polymer-based surfaces such as PMMA and PTFE, and conventional metals like aluminum and stainless steel. In addition, the static and dynamic contact angles for all the control surfaces were also measured in order to correlate the measured ice adhesion strength with the surface wettability. Furthermore, surface topography analysis was performed to acquire the 3-D surface profiles along with the averaged surface roughness in order to examine the effects of surface roughness on ice adhesion strength. Similarly, the ice adhesion strength was also analyzed at different temperatures (i.e., -50C, -100C, -150C and -200C ) to reveal the temperature effects on the ice adhesion strength over hydrophilic and hydrophobic surfaces. The influence of the durability of surface coatings on the ice adhesion performance of hydro-/ice-phobic coatings was also investigated experimentally in the present study. In coordinating with the experimental study, a numerical analysis was also performed to explore/optimize experimental design paradigms to minimize the measurement uncertainties

Production monitoring and performance of recycled aggregates from construction and demolition waste

This internship report is about production, monitoring and performance of recycled aggregates (RA) from construction and demolition wastes (CDW). Use of RA can be useful for environmental protection and economic terms. The focus of this internship was to identify the basic properties of RA produced in the company. Natural aggregates present in the Laboratory of Institute Polytechnic of Leiria are used as reference aggregates. Similarly, the properties of RA concrete were determined and explained here. Concrete is prepared considering natural aggregate concrete as base concrete, RA of 20% and RA of 100%. Basic concrete properties like slump test, compressive strength, Ultrasonic pulse velocity test explained here for different combinations. Use of RA has been found useful for pavement construction. Reasons for use of RA in pavement construction, with experimental results are explained here in detail

Marketing System and Efficiency of Indian Major Carps in India

The Kolleru Lake area (KLA) in Andhra Pradesh being a predominant centre for carp culture is known as the ‘Carp Pocket of India’. This paper has described the highly efficient fish marketing system prevalent in the KLA and has compared it with the marketing of Indian Major Carps (IMC) in other major aquaculture states like West Bengal and Orissa and marine states like Maharashtra and Tamil Nadu. The marketing channels, market intermediaries, price spread and marketing efficiency have been presented. A comparison of the marketing channels at several fish markets has revealed that the price spread for IMC from Kolleru is highest at the Mumbai market and lowest at the Coimbatore market. Consequently, fishermen’s share in consumer price has been found highest for Coimbatore at 61.54 per cent and lowest for Mumbai at 47.06 per cent. Similarly, the marketing efficiency was the highest for Coimbatore at 2.60 and lowest for Mumbai at 1.89. Retail price for KLA carps has been found lower than locally cultured carps at various areas, reflecting the efficiency of the marketing channel in providing cheap fish transported over large distances and through a large number of intermediaries. The reasons for the efficient IMC marketing system at KLA have been discussed and the study has recommended the development of efficient fish marketing system in other parts of the country.Agricultural and Food Policy,

Electrochemical analysis of austenitic stainless steel of type 304L SS in nitric acid medium

Austenitic stainless steels type 304L and 316L are largely used as structural materials for equipments handling nitric acid media in nuclear reprocessing plants. In almost all nitric media, these materials, protected by a chromium oxide rich layer, remain in their passive state. However, in some particular nitric media, their corrosion potential may be shifted towards their transpassive domain. The corrosion potential of the steel depends greatly on the cathodic reaction involved in the oxidoreduction process between the elements Fe, Cr, Ni of the steel and the oxidizing species of the medium. In this experiment, we have observed corrosion behavior of 304L SS by both electrochemical analysis and non-electrochemical analysis in different nitric acid concentrations such as 0.4M, 0.5M, 0.6M, 1M, 2M and concentrated solution. We measured corrosion rate and relation between corrosion current and corrosion rate by Tafel extrapolation method. Surface morphology of corroded surfaces were analysed by using AFM. The Micro hardness test was carried out to measure the hardness of both the non-corroded and corroded specimens. It is observed that the corrosion current density is inversely proportional to the corrosion potential and implies same pattern of corrosion tendency. The AFM results, we found that there is decreasing the density of pits on the surface by increasing concentration of nitric acid solution

QoS Evaluation of SIP Signalled VoIP Network Routed using MANET Routing Protocols

A Mobile ad hoc network MANET is a type of network which consists of group of mobile nodes which are wireless and do not have fixed architecture The nodes act as a router and depict the nature of dynamism The three different classification of protocols in MANETS supports different applications But to support real time applications like voice signalling and video signalling we require the most efficient protocol that gives the QoS mechanism Voice and video signalling demand to know the performance of different metrics in the network such as end-to-end delay overall throughput of network and jitter of the network This paper works on identifying and analyzing the performance of various protocols like AODV DSR OLSR and TORA which would help in fulfilling the mentioned need Voice over Internet Protocol VoIP also known as IP telephony is a class of technologies used to deliver voice and multimedia sessions over internet protocol network

POTHOLE DETECTION SYSTEM

Aging roads and poor road-maintenance systems result a large number of potholes, whose numbers increase over time. Potholes jeopardize road safety and transportation efficiency. Moreover, they are often a contributing factor to car accidents. To address the problems associated with potholes, the locations and size of potholes must be determined quickly. Sophisticated road-maintenance strategies can be developed using a pothole database, which requires a specific pothole-detection system that can collect pothole information at low cost and over a wide area. However, pothole repair has long relied on manual detection efforts. Recent automatic detection systems, such as those based on vibrations or laser scanning, are insufficient to detect potholes correctly and inexpensively owing to the unstable detection of vibration-based methods and high costs of laser scanning-based methods. Thus, in this paper, we introduce a new pothole-detection system using a commercial black-box camera. The proposed system detects potholes over a wide area and at low cost. We have developed a novel pothole-detection algorithm specifically designed to work with the embedded computing environments of black-box cameras. Experimental results are presented with our proposed system, showing that potholes can be detected accurately in real-time

GRITv2: Efficient and Light-weight Social Relation Recognition

Our research focuses on the analysis and improvement of the Graph-based Relation Inference Transformer (GRIT), which serves as an important benchmark in the field. We conduct a comprehensive ablation study using the PISC-fine dataset, to find and explore improvement in efficiency and performance of GRITv2. Our research has provided a new state-of-the-art relation recognition model on the PISC relation dataset. We introduce several features in the GRIT model and analyse our new benchmarks in two versions: GRITv2-L (large) and GRITv2-S (small). Our proposed GRITv2-L surpasses existing methods on relation recognition and the GRITv2-S is within 2% performance gap of GRITv2-L, which has only 0.0625x the model size and parameters of GRITv2-L. Furthermore, we also address the need for model compression, an area crucial for deploying efficient models on resource-constrained platforms. By applying quantization techniques, we efficiently reduced the GRITv2-S size to 22MB and deployed it on the flagship OnePlus 12 mobile which still surpasses the PISC-fine benchmarks in performance, highlighting the practical viability and improved efficiency of our model on mobile devices