Feed channel spacer characteristics and their optimisation

The optimization of the spiral wound module design generally refers to the optimization of feed channel spacers, which is investigated in this thesis. The feed channel spacers serve to improve the mass transfer by promoting turbulence and provide passage for the fluid. However, the presence of spacers also significantly increases the channel pressure drop and consequently increases the energy costs of the process. The spacer design could therefore have a significant effect on process economics. The main aim of this work was to study spacer characteristics and test its major geometrical characteristics. To achieve this, custom designed spacers were developed in the laboratory and CFD simulations were used to visualize the flow management that spacer can achieve. Through experiments and CFD simulation, it was found that the transverse filament was one of the dominating factors in spacer design. Most of the pressure drop in the spacer filled channel was caused by the form drag introduced by the transverse filaments. The variation in transverse filament distance can greatly affect the number of transverse filaments in the channel and consequently affect the pressure drop and mass transfer in the channel. The experimental results showed that the diameter of the transverse filament also had a significant effect on channel pressure drop and mass transfer, especially at high flow rates. Increasing transverse filament diameter may result in a rapid increase in pressure drop and mass transfer caused by increased from drag and enhanced turbulence. Voidage alone was found not to be efficient for quantifying the geometrical properties of spacer filled channels. Two ratios, transverse filament diameter/channel height and transverse filament diameter/transverse distance, were established for quantifying the performance of the spacer filled channels. Novel spacers were developed as the result of this research. They provide similar mass transfer performance to the benchmark commercial spacer with lower pressure drop. Optimal novel spacer design was analysis based on economics analysis

Simulating the Integration of Urban Air Mobility into Existing Transportation Systems: A Survey

Urban air mobility (UAM) has the potential to revolutionize transportation in metropolitan areas, providing a new mode of transportation that could alleviate congestion and improve accessibility. However, the integration of UAM into existing transportation systems is a complex task that requires a thorough understanding of its impact on traffic flow and capacity. In this paper, we conduct a survey to investigate the current state of research on UAM in metropolitan-scale traffic using simulation techniques. We identify key challenges and opportunities for the integration of UAM into urban transportation systems, including impacts on existing traffic patterns and congestion; safety analysis and risk assessment; potential economic and environmental benefits; and the development of shared infrastructure and routes for UAM and ground-based transportation. We also discuss the potential benefits of UAM, such as reduced travel times and improved accessibility for underserved areas. Our survey provides a comprehensive overview of the current state of research on UAM in metropolitan-scale traffic using simulation and highlights key areas for future research and development

Investigation of Taylor impact test of isotropic and anisotropic material through geometrical characteristics of specimens

In this thesis, high strain rate properties of isotropic material (a copper alloy) and anisotropic material (2195-T8 aluminum-lithium alloy) are investigated using Taylor impact tests. Coordinate measuring machines (CMMs) are used to measure the shape of specimens after the deformation. The geometrical data enables us to determine the plastic distributions and the dynamic yield stresses of specimens. A raise in yield strength is found in the copper alloy during the impact. It means that material properties of the copper alloy are sensitive to high strain rate. Yet such phenomenon is not found in the 2195-T8 aluminum-lithium alloy. Based on the uniaxial compression strain state in the barreling regions of the specimens, the dynamic yield stresses in the rolling, transverse and short transverse directions are obtained for the 2195-T8 aluminum-lithium alloy. This enables us to determine the anisotropic coefficients in Hill’s criterion and carry out the finite element analysis. The dependencies of fracture are also investigated. It is found that the fracture is sensitive to maximum shear stress, equivalent plastic strain and stress triaxiality

The adhesive interactions between graphene and substrates by blister tests

A blister test and associated analysis was developed to characterize the interfacial adhesion between graphene and copper and silicon substrates to which it has been transferred. Chemical vapor deposition grown graphene had been transferred to a highly polished copper or silicon substrate from its seed foil. The graphene/photoresist or graphene/PDMS/photoresist composite film was pressurized with deionized water through a hole in the substrate and the deflection of the membrane was measured by a full field interference method. Different mixed-mode conditions were achieved by varying the thickness of the backing layers. The measured adhesion energy for the graphene/copper and graphene/silicon interfaces showed a strong dependence on the mode-mix. The deflection profiles were modeled by plate, membrane theory and finite element analysis. The variation of energy release rate with blister radius and thickness for graphene/copper and graphene/silicon interfaces were obtained. The traction-separation relations of the graphene/copper interface were determined in the modified blister tests. The blister profiles and normal crack opening displacements were measured by two synchronized camera. Cohesive zone models associated with traction-separation relations were developed to study the damage initiation and crack propagation under various mixed-mode conditions. It was determined that the maximum normal and shear strength, which governed damage initiation, was independent of the mode-mix. The softening parameter, which governed damage evolution, was also independent of the mode mix. The numerical solution for and experimental measurements of the pressure vs. blister radius and deflection, as well as NCOD were in good agreement. A model for the variation of traction-separation relations with mode-mix was developed based on an asperity shielding model. The delamination paths of the graphene/photoresist, and graphene/PDMS/photoresist samples and the quality of graphene after the blister test were confirmed by Raman spectroscopy. The use of pressure could provide a path to large-scale graphene transfer.Engineering Mechanic

Weakly Supervised GAN for Image-to-Image Translation in the Wild

Generative Adversarial Networks (GANs) have achieved significant success in unsupervised image-to-image translation between given categories (e.g., zebras to horses). Previous GANs models assume that the shared latent space between different categories will be captured from the given categories. Unfortunately, besides the well-designed datasets from given categories, many examples come from different wild categories (e.g., cats to dogs) holding special shapes and sizes (short for adversarial examples), so the shared latent space is troublesome to capture, and it will cause the collapse of these models. For this problem, we assume the shared latent space can be classified as global and local and design a weakly supervised Similar GANs (Sim-GAN) to capture the local shared latent space rather than the global shared latent space. For the well-designed datasets, the local shared latent space is close to the global shared latent space. For the wild datasets, we will get the local shared latent space to stop the model from collapse. Experiments on four public datasets show that our model significantly outperforms state-of-the-art baseline methods

Monoclonal Antibodies to Lipopolysaccharide Antigens of Salmonella enterica serotype Typhimurium DT104

Salmonella enterica subsp. enterica serotype Typhimurium is one of the major causative agents of human gastroenteritis. Here we raised a panel of 45 monoclonal antibodies (MAbs) against ser. Typhimurium DT104 by immunizing mice with formalin-killed bacteria and demonstrated that all the MAbs recognized the bacterial lipopolysaccharide (LPS) antigen. These MAbs were specific for group O:4 Salmonella with very little or no cross-reactivity with other closely related bacteria and were able to bind to the cell surface of live bacterial cells, making them potential candidates for capture and concentration of the pathogen in food and water samples. Epitope characterization revealed that the O:5 antigen present in the LPS of some serogroup 4 Salmonella is the critical factor for the binding of these MAbs to LPS. This study has provided some insights into the structure of the Salmonella LPS and its influence on the antigenicity of LPS

The Interactions between E-Shopping and Store Shopping: A Case Study of the Twin Cities

This research aims to reveal the interactions between e-shopping and in-store shopping using a sample of Internet users in the Minneapolis-St. Paul metropolitan area. This report summarizes previous research on the interactions among spatial attributes, e-shopping, and travel behavior and makes eight recommendations for future research. Guided by the recommendations, this study adopts an innovative research design by integrating a conventional shopping survey with an activity diary. This report provides a detailed description of survey development and implementation and points out several common pitfalls in survey administration. This report also presents results on the interactions. Specifically, two ordered probit models and structural equation models were developed to investigate the influence of geography on online shopping usage and the influence of e-shopping on traditional shopping