Modeling Fluid Interactions with Granular and Fibrous Surfaces

Understanding the interactions between a body of liquid and a curvy surface is important for many applications such as underwater drag force reduction, droplet filtration, self-cleaning, and fog harvesting, among many others. This study investigates ways to predict the performance of granular and fibrous surfaces for some of the above applications. More specifically, our study is focused on 1) modeling the mechanical stability of the air-water interface over submerged superhydrophobic (SHP) surfaces and their expected drag reduction benefits, and 2) predicting the mechanical stability of a droplet on a fiber in the presence of an external body force. For the first application, we modeled the air–water interface over submerged superhydrophobic coatings comprised of particles/fibers of different diameters or Young–Laplace contact angles. We developed mathematical expressions and modeling methodologies to determine the maximum depth to which such coatings can be used for underwater drag reduction as well as the magnitude of the depth-dependent drag reduction effect of the surface. For the second application, we studied the force required to detach a droplet from a single fiber or from two crossing fibers. The results of our numerical simulations were compared to those obtained from experiment with ferrofluid droplets under a magnetic field, and excellent agreement was observed. Such information is of crucial importance in design and manufacture of droplet–air and droplet–fluid separation media, fog harvesting media, protective clothing, fiber-reinforced composite materials, and countless other applications

Sustainability and innovation of the sweet cherry supply chain

La ciliegia (Prunus Avium L.) è uno dei frutti più apprezzati a livello mondiale grazie alle caratteristiche organolettiche (gusto, dolcezza e colore) e alla naturale presenza di nutrienti, antiossidanti e altri composti. L'Italia è il quarto produttore mondiale di ciliegie dopo Turchia, Stati Uniti d'America e Iran (Repubblica dell'Islam). In particolare, la Puglia rappresenta la prima regione italiana di produzione di ciliegie che ha contribuito nel 2017 per il 32% alla produzione nazionale annuale. Attualmente il suo settore deve affrontare continue sfide economiche, ambientali e sociali per rimanere competitivi sul mercato globale. È necessario cercare soluzioni, ad esempio tecnologie innovative, che migliorino la produttività, la redditività e la sostenibilità secondo quanto previsto anche dalle recenti norme agricole europee (PAC 2014-2020) che promuovano l'innovazione/internazionalizzazione dell'impresa attraverso specifici finanziamenti. La ricerca fornisce informazioni importanti per promuovere e migliorare la filiera cerasicola in termini di sostenibilità ambientale, economica e sociale applicando la metodologia del Carbon Footprint (CF), basata sull’approccio del Life Cycle Assessment (LCA), su dati reali di produzione e di trasformazione della ciliegia forniti da aziende situate in Puglia. Nello specifico è presentato un caso studio sulla produzione agricola e confezionamento di ciliegie di due aziende situate in Puglia (Sud Italia). Esso comprende la gestione del frutteto dalla fase di coltivazione in serra delle piantine a quella di raccolta, considerando l'intero ciclo di vita del frutteto pari a 20 anni; e la lavorazione delle ciliegie dolci, dalla raccolta nel frutteto al centro raccolto dove vengono confezionate per la vendita. L’analisi evidenzia gli impatti derivanti dalla fase di gestione agricola sono pari a 0.656 kgCO2eq, quelli relativi alla fase di lavorazione sono 0.068 kgCO2eq, mentre quelli della fase di produzione dei cestini in PET è pari a 0.0744 kgCO2eq. Per quanto riguarda la fase agricola, invece, il principale impatto deriva dal consumo di energia elettrica per l’estrazione di acqua delle falde acquifere per le attività di irrigazione e di fertirrigazione (15,6% del totale di kgCO2eq), dal trasporto del letame (4,7% del totale di kgCO2eq) e dalla aratura (3,53% del totale di kgCO2eq). Quanto osservato nel presente studio potrebbe contribuire a fornire informazioni utili agli agricoltori, all'industria alimentare e a chiunque ne abbia interesse per promuovere o migliorare la filiera cerasicola in termini di sostenibilità ambientale. Inoltre, la ricerca ha creato una base per lo sviluppo di una specifica certificazione di prodotto (etichettatura del carbonio) che tenga conto delle pratiche aziendali sostenibili adottate. In questo modo, i produttori/imprenditori del settore hanno l'opportunità di comunicare ai consumatori (sempre più attenti a questi aspetti) le loro politiche di sostenibilità così da rafforzare e migliorare la reputazione aziendale.Sweet cherry (Prunus avium L.) is one of the most appreciated fruits worldwide thanks to the organoleptic characteristics (i.e. taste, sweetness and colour) as well as the natural presence of nutrients, antioxidants and other healthy compounds such as i.e. flavonoids, vitamins, anthocyanins and phenolic. Italy is the fourth top world cherries producer after Turkey, United States of America, and Iran (Islam Republic of). In particular, Apulia represents the first Italian cherry production region contributing in 2017 with 32% to the annual national production. Although this fruit is important worldwide, its sector has to face continuous challenges in different fields i.e. economic, environmental and social to remain competitive on the global market. For these reasons, it is needed to search solutions (for instance introducing innovation technologies) that improve productivity, profitability and sustainability according to agricultural European rules (i.e. Common Agricultural Policy – CAP 2014-2020) that promote the innovation/internationalization of enterprise through operational funds. The research presents a case study of cherries supply chain managed by two firms situated in Apulia region (South Italy). The aim is to calculate GHG emissions of the sweet cherry, according to CF methodology based on Life Cycle Assessment (LCA) approach. The supply chain considered two phases: agriculture and processing. The former includes orchard management from nursery to harvesting and considering the entire orchard life cycle equal to 20 years; whereas the latter examines the processing of sweet cherries, from harvesting in the orchard to the collected centre where they are packaged for the fresh market. The study highlights that the GWP100 associated with the system investigated is equal to 0.798 kg CO2eq per 0.5 kg of fresh sweet cherry packed in PET clamshell. In particular, the study shown that the impacts coming from the agricultural management stage is equal to 0.656 kgCO2eq, the processing is 0.068 kgCO2eq and clamshell PET production is 0.0744 kgCO2eq.vAs regard the orchard phase, the principal impact derives from the full production where the most GWP100 impact is represented by the utilisation of the groundwater pumping station (electricity, low voltage production) for the irrigation and fertigation activities (15.6% of the total CO2eq), by the transport of manure (4.7% of the total CO2eq) and by the ploughing (3.53% of the total CO2eq). These results could contributes to provide information to stakeholders involved in the sweet cherry supply chain to promote or enhance a sweet cherry production mainly environmental sustainable

Lattice Boltzmann Modelling of Droplet Dynamics on Fibres and Meshed Surfaces

Fibres and fibrous materials are ubiquitous in nature and industry, and their interactions with liquid droplets are often key for their use and functions. These structures can be employed as-is or combined to construct more complex mesh structures. Therefore, to optimise the effectiveness of these structures, the study of the wetting interactions between droplets and solids is essential. In this work, I use the numerical solver lattice Boltzmann method (LBM) to systematically study three different cases of droplet wetting, spreading, and moving across fibres, and droplets impacting mesh structures. First, I focus on partially wetting droplets moving along a fibre. For the so-called clamshell morphology, I find three possible dynamic regimes upon varying the droplet Bond number and the fibre radius: compact, breakup, and oscillation. For small Bond numbers, in the compact regime, the droplet reaches a steady state, and its velocity scales linearly with the driving body force. For higher Bond numbers, in the breakup regime, satellite droplets are formed trailing the initial moving droplet, which is easier with smaller fibre radii. Finally, in the oscillation regime (favoured in the midrange of fibre radius), the droplet shape periodically extends and contracts along the fibre. Outside of the commonly known fully wetting and partial wetting states, there exists the pseudo-partial wetting state (where both the spherical cap and the thin film can coexist together), which few numerical methods are able to simulate. I implement long-range interactions between the fluid and solid in LBM to realise this wetting state. The robustness of this approach is shown by simulating a number of scenarios. I start by simulating droplets in fully, partial, and pseudo-partial wetting states on flat surfaces, followed by pseudo-partially wetting droplets spreading on grooved surfaces and fibre structures. I also explore the effects of key parameters in long-range interactions. For the dynamics demonstration, I simulate droplets in the pseudo-partial wetting state moving along a fibre in both the barrel and clamshell morphologies at different droplet volumes and fibre radii. Finally, I focus on the dynamics of droplets impacting square mesh structures. I systematically vary the impact point, trajectory, and velocity. To rationalise the results, I find it useful to consider whether the droplet trajectory is dominated by orthogonal or diagonal movement. The former leads to a lower incident rate and a more uniform interaction time distribution, while the latter is typically characterised by more complex droplet trajectories with less predictability. Then, focussing on an impact point, I compare the droplet dynamics impacting a single-layer structure and equivalent double-layer structures. From a water-capturing capability perspective (given the same effective pore size), a double-layer structure performs slightly worse. A double-layer structure also generally leads to shorter interaction time compared to a single-layer structure

Lightweight, High-Temperature Radiator for In-Space Nuclear-Electric Power and Propulsion

The desire to explore deep space destinations with high-power and high-speed spacecraft inspired this work. Nuclear Electric Propulsion (NEP), shown to provide orders of magnitude higher specific impulse and propulsion efficiency over traditional chemical rockets, has been identified as an enabling technology for this goal. One of large obstacle to launching an NEP vehicle is total mass. Increasing the specific power (kW/kg) of the heat radiator component is necessary to meet NASA’s mass targets. This work evaluated a novel lightweight, high-temperature carbon fiber radiator designed to meet the mass requirements of future NEP missions. The research is grouped into three major sections: 1) a micro-scale radiation study, 2) bench-scale experimental and analytical investigations, and 3) large-scale radiator system modeling. In the first section, a Monte Carlo ray tracing model built to predict the effective emissivity of a carbon fiber fin by modeling the radiation scattering among fibers showed that the added surface area of the fibers over a flat fin surface increases the effective emissivity of the radiator area by up to 20%. The effective emissivity increases as the fiber volume fraction decreases from 1 to about 0.16 due to increased scattering among the fibers. For fiber volume fractions lower than 0.10, the effective emissivity decreases rapidly as the effect of radiation transmission becomes significant. In the second section, thermal analyses of the carbon fiber radiator fin predicted that these radiators could meet NASA’s performance targets by reducing the areal density to 2.2 kg/m2 or below. These models were validated through experimental tests conducted on sub-scale radiator test articles. This work elevated the technology readiness level (TRL) of the carbon fiber radiator fin from level 2 to 4. In the last section, a radiator system model for an NEP vehicle was built to analyze the dependence of radiator mass on selected system parameters. The model was used to minimize the radiator mass for test cases. The results predicted that carbon fiber fins operated near 600°C reduced the radiator mass by a factor of 7 as compared with traditional radiators operating near 100°C. This significant mass-reduction could enable future NEP systems

A novel parallel algorithm for surface editing and its FPGA implementation

A thesis submitted to the University of Bedfordshire in partial fulfilment of the requirements for the degree of Doctor of PhilosophySurface modelling and editing is one of important subjects in computer graphics. Decades of research in computer graphics has been carried out on both low-level, hardware-related algorithms and high-level, abstract software. Success of computer graphics has been seen in many application areas, such as multimedia, visualisation, virtual reality and the Internet. However, the hardware realisation of OpenGL architecture based on FPGA (field programmable gate array) is beyond the scope of most of computer graphics researches. It is an uncultivated research area where the OpenGL pipeline, from hardware through the whole embedded system (ES) up to applications, is implemented in an FPGA chip. This research proposes a hybrid approach to investigating both software and hardware methods. It aims at bridging the gap between methods of software and hardware, and enhancing the overall performance for computer graphics. It consists of four parts, the construction of an FPGA-based ES, Mesa-OpenGL implementation for FPGA-based ESs, parallel processing, and a novel algorithm for surface modelling and editing. The FPGA-based ES is built up. In addition to the Nios II soft processor and DDR SDRAM memory, it consists of the LCD display device, frame buffers, video pipeline, and algorithm-specified module to support the graphics processing. Since there is no implementation of OpenGL ES available for FPGA-based ESs, a specific OpenGL implementation based on Mesa is carried out. Because of the limited FPGA resources, the implementation adopts the fixed-point arithmetic, which can offer faster computing and lower storage than the floating point arithmetic, and the accuracy satisfying the needs of 3D rendering. Moreover, the implementation includes Bézier-spline curve and surface algorithms to support surface modelling and editing. The pipelined parallelism and co-processors are used to accelerate graphics processing in this research. These two parallelism methods extend the traditional computation parallelism in fine-grained parallel tasks in the FPGA-base ESs. The novel algorithm for surface modelling and editing, called Progressive and Mixing Algorithm (PAMA), is proposed and implemented on FPGA-based ES’s. Compared with two main surface editing methods, subdivision and deformation, the PAMA can eliminate the large storage requirement and computing cost of intermediated processes. With four independent shape parameters, the PAMA can be used to model and edit freely the shape of an open or closed surface that keeps globally the zero-order geometric continuity. The PAMA can be applied independently not only FPGA-based ESs but also other platforms. With the parallel processing, small size, and low costs of computing, storage and power, the FPGA-based ES provides an effective hybrid solution to surface modelling and editing

Research and technology

As the NASA Center responsible for assembly, checkout, servicing, launch, recovery and operational support of Space Transportation System elements and payloads, Kennedy Space Center is placing emphasis on its research and technology program. In addition to strengthening those areas of engineering and operations technology that contribute to safer, more efficient, and more economical execution of our current mission, we are developing the technological tools needed to execute the Center's mission relative to future programs. The Engineering Development Directorate encompasses most of the laboratories and other Center resources that are key elements of research and technology program implementation, and is responsible for implementation of the majority of the projects in this Kennedy Space Center 1988 Annual Report

Inverted Fluorescence Microscope

Team F13 is composed of Trevor Blythe, Spencer Hann, Matthew Pfeiffer, and Thomas Eggenberger. We are all majoring in mechanical engineering and in our final year of study here at Cal Poly San Luis Obispo. This project is a continuation of a 2019-2020 senior project. The previous team designed and built a functioning inverted fluorescence microscope (IFM) from scratch. This device was created as a lab tool for undergraduate students to be able to perform experiments on microfluidic devices constructed in Cal Poly’s Microfabrication Laboratory. Although substantially functional, several design constraints had not yet been met. Our team has improved microscope robustness and functionality for practical undergraduate lab use. To do this, we set overarching goals including decreasing microscope footprint, increasing the accuracy of microscope positional repeatability, and improving user-friendliness. Within this Final Design Review report, the full design, manufacturing, and testing processes of this project are explicitly detailed, as well as project logistics, future suggestions, and project management

Microbial Load Monitor

The Microbial Load Monitor (MLM) is an automated and computerized system for detection and identification of microorganisms. Additionally, the system is designed to enumerate and provide antimicrobic susceptibility profiles for medically significant bacteria. The system is designed to accomplish these tasks in a time of 13 hours or less versus the traditional time of 24 hours for negatives and 72 hours or more for positives usually required for standard microbiological analysis. The MLM concept differs from other methods of microbial detection in that the system is designed to accept raw untreated clinical samples and to selectively identify each group or species that may be present in a polymicrobic sample

DEVELOPMENT AND ANALYSIS OF HYBRID SOLAR DRYER WITH BIOMASS BACKUP HEATER

The application of solar drying, especially in the agricultural areas, has been proven to be practical, economical, and environmental friendly. However, the drying process is limited only on a sunny environment and often interrupted during the cloudy or rainy days and also at night. A hybrid dryer with thermal backup technique has been adopted to overcome the limitation of solar dryer. The combination of the systems is expected to create 24 hours a day of non-interrupted drying process. The study on the drying system was carried out by three analysis techniques; analytical, experimental and numerical. The conceptual design of the experimental model was based on analytical modeling of the drying process using solar, or the backing up heat source, or both of them simultaneously. The work was extended to involve numerical simulation of the fluid flow inside the developed hybrid dryer by employing CFD technique using FLUENT® software under different operational modes. Chillies and empty fruit bunch (EFB) as food and waste product respectively has been selected for the materials to be dried. They were dried under different modes, which were ‘only solar’, ‘thermal backup alone’ and ‘solar-thermal backup’ (hybrid). Open sun drying was also conducted and considered as a reference for comparison. It was found that the fastest drying process was in the hybrid drying mode. Moisture content of chillies and EFB were reduced from 80% to 5% and 75% to 6% within 2.33 and 1.33 days of drying, respectively. The hybrid drying efficiencies of chillies and EFB were considerably high as compared to only solar and thermal alone mode which were 6.85% and 11% respectively. The experimental measurements have shown good agreement with the simulated results, with maximum percent of error of 15%. Hybrid mode was the most appropriate mode for drying application since it meets the required drying temperature. Also, it was capable to reduce the drying period considerably. The simulation results were validated by comparing with the experimental measurements