MICROWAVE HEATING SIMULATION OF METALS AND DIELECTRIC CERAMICS

The research objectives proposed to study metal processing using a modular industrial microwave oven. The intent of the oven was to perform casting for metal processing purposes. The research objectives were to validate the ovens performance for melting copper and then to compare the results to modeling data. The initial intent was to test the oven for its capability to melt metals. Most researchers would argue that the industrial microwave could not be used for metal processing. However, this research proposed to answer the question as to whether the industrial microwave oven could be used for processing metals or not. The strength of the research lies in the fact that the technology had not been tested on a global scale and industry has not accepted the capabilities of the oven. Nevertheless, developmental efforts have continued and the microwave technology has not ceased to be developed. Although there would be problematic issues, the focus was not to prove the theoretical equations and derive large data sets for the experiments; but to validate that the oven could be used for processing metals and used in an industrial setting where alternative metal processing technologies exist. In order to perform the research, the unit was designed and manufactured and auxiliary components purchased. The research proposed to cast copper in the experimental modular microwave oven and compare the data to the modeling data. Data collection was basically coordinated using thermocouples along the mold and an optical pyrometer for the metal. The final casts were analyzed for both metallurgical and chemical characteristics. A model was designed based upon the dimensions and operational parameters of the experimental oven and data comparison was made. A simulator was then derived using computer code to formulate a user interface panel and simulation environment representative of a laboratory environment. In order to pursue the research goals, material properties were derived as functions of temperature. For the electromagnetic properties the dielectric permittivity was required along with suggestions for the electromagnetic boundary conditions. An experiment was developed and the properties were measured for several dielectric materials; thus the most suitable ceramic material chosen

Design of colon phantoms and a colon phantom motorized measuring system to verify the operation of a microwave-based diagnostic device

Treballs Finals de Grau d'Enginyeria Biomèdica. Facultat de Medicina i Ciències de la Salut. Universitat de Barcelona. Curs: 2022-2023. Tutor/Director: Fernández Esparrach, Glòria, Guardiola García, MartaMicrowave imaging (MWI) is an emerging medical imaging technique with promising biomedical applications. In line with this research area, MiWEndo Solutions is a spinoff devoted to the development of a MWI device for colorectal cancer diagnosis called MiWEndo, which is attached to the regular colonoscope. Before its actual commercialization, a fundamental step towards the validation of the MiWEndo prototype is the design of realistic colon tissue-mimicking phantoms. Such phantoms allow the assessment of the imaging system performance under well controlled and reproducible conditions. In this thesis, a new, simple, and highly reproducible phantom recipe based on polyvinylpyrrolidone (PVP) has been developed to mimic healthy colon mucosa. Moreover, a comparative study between the currently used oil-based phantom recipe and the new PVP phantom has been conducted to assess the lifespan and stability of each type of fabricated phantom. It has been concluded that PVP phantoms must be conserved in the fridge for increased stability. With this conservation protocol, the PVP recipe shows a similar lifespan as the oil-based one. Nevertheless, due to both the limited number of samples and time, further studies must be carried out to conclusively determine the recipe with larger stability. Furthermore, a colon phantom motorized measuring system has been designed to improve repeatability and reliability in the measurements of the phantoms. The system consists of an XYZ motorized positioning system, an Arduino Nano, stepper motor drivers and Arduino IDE firmware. Even though further improvements will be required once implemented, a first conception of a system that fulfils the established requirements has been obtained, based on reasonable-cost and simple-implementation components. Besides, a successful proof of concept of the measuring system has been carried out, concluding that a further implementation of the system seems viable

Integrated navigation and visualisation for skull base surgery

Skull base surgery involves the management of tumours located on the underside of the brain and the base of the skull. Skull base tumours are intricately associated with several critical neurovascular structures making surgery challenging and high risk. Vestibular schwannoma (VS) is a benign nerve sheath tumour arising from one of the vestibular nerves and is the commonest pathology encountered in skull base surgery. The goal of modern VS surgery is maximal tumour removal whilst preserving neurological function and maintaining quality of life but despite advanced neurosurgical techniques, facial nerve paralysis remains a potentially devastating complication of this surgery. This thesis describes the development and integration of various advanced navigation and visualisation techniques to increase the precision and accuracy of skull base surgery. A novel Diffusion Magnetic Resonance Imaging (dMRI) acquisition and processing protocol for imaging the facial nerve in patients with VS was developed to improve delineation of facial nerve preoperatively. An automated Artificial Intelligence (AI)-based framework was developed to segment VS from MRI scans. A user-friendly navigation system capable of integrating dMRI and tractography of the facial nerve, 3D tumour segmentation and intraoperative 3D ultrasound was developed and validated using an anatomically-realistic acoustic phantom model of a head including the skull, brain and VS. The optical properties of five types of human brain tumour (meningioma, pituitary adenoma, schwannoma, low- and high-grade glioma) and nine different types of healthy brain tissue were examined across a wavelength spectrum of 400 nm to 800 nm in order to inform the development of an Intraoperative Hypserpectral Imaging (iHSI) system. Finally, functional and technical requirements of an iHSI were established and a prototype system was developed and tested in a first-in-patient study

Technology 2000, volume 1

The purpose of the conference was to increase awareness of existing NASA developed technologies that are available for immediate use in the development of new products and processes, and to lay the groundwork for the effective utilization of emerging technologies. There were sessions on the following: Computer technology and software engineering; Human factors engineering and life sciences; Information and data management; Material sciences; Manufacturing and fabrication technology; Power, energy, and control systems; Robotics; Sensors and measurement technology; Artificial intelligence; Environmental technology; Optics and communications; and Superconductivity

Analysis and enhancement of resin flow in liquid composite molding process

2016 - 2017The research activity was devoted to the study of the composite materials manufacturing processes. In particular, the liquid composite molding (LCM) processes were the object of the performed study. In recent years LCM processes have gained a widespread diffusion in different industrial fields, from civil to automotive and aerospace due to their several advantages compared to the conventional autoclave processes. However, some disadvantages related to a not uniform preform impregnation due to a local variation of the preform permeability, fibers bundles misalignment, that would results in dry zones or matrix richer areas, affect the LCMs limiting their usage in industrial full scale. Other limits are due to a limited pressure driving force as well as a reduced pressure compaction influencing the final volume fraction achievable with detrimental effects on the mechanical properties of the composite material product. A more deep knowledge of the phenomena involved in the manufacturing of the composite materials are required to implement proper control action on the parameters (e.g. pressure, resin flow rate, thermal cycle as well as inlet/vent locations) to optimize the process. In order to improve the impregnation of the preform and reduce the time required to fully fill the mold cavity an in-line microwave preheating system was developed. The aims was to couple a microwave generator upstream the LCM mold to heat up the resin prior the entry into the mold. Indeed, the temperature increasing reduces the liquid viscosity allowing the resin to flow more freely through the dry preform. To perform a thorough study on the effectiveness of the proposed approach a laboratory scale apparatus for liquid composite molding processes was designed. The system was instrumented with ad-hoc designed sensors to monitor the resin flow during the process. Cheaper dielectric sensors are designed, produced and installed on the mold. A numerical model was also developed to simulate the resin flow through the fibers preform. The numerical model proved to able to deal with the dual-scale nature of the textile preform commonly used in the LCMs, that are characterized by two different regions (inter- and intra-tow) with different values of permeability. The numerical outcomes were also used to validate the data obtained from the dielectric sensors. They demonstrated to be able to monitor the both the impregnation and the saturation of the fiber preform. The developed microwave heating system proved to be effective to both reduce the total infusion time as well as improve the wetting of the fibers, achieving a more uniform impregnation with a limited amount of residual voids.[edited by Author]XVI n.s. (XXX ciclo

Microfluidics and Nanofluidics Handbook

The Microfluidics and Nanofluidics Handbook: Two-Volume Set comprehensively captures the cross-disciplinary breadth of the fields of micro- and nanofluidics, which encompass the biological sciences, chemistry, physics and engineering applications. To fill the knowledge gap between engineering and the basic sciences, the editors pulled together key individuals, well known in their respective areas, to author chapters that help graduate students, scientists, and practicing engineers understand the overall area of microfluidics and nanofluidics. Topics covered include Finite Volume Method for Numerical Simulation Lattice Boltzmann Method and Its Applications in Microfluidics Microparticle and Nanoparticle Manipulation Methane Solubility Enhancement in Water Confined to Nanoscale Pores Volume Two: Fabrication, Implementation, and Applications focuses on topics related to experimental and numerical methods. It also covers fabrication and applications in a variety of areas, from aerospace to biological systems. Reflecting the inherent nature of microfluidics and nanofluidics, the book includes as much interdisciplinary knowledge as possible. It provides the fundamental science background for newcomers and advanced techniques and concepts for experienced researchers and professionals

Технології виробництва заготовок литтям

У навчальному посібнику «Технології виробництва заготовок литтям» розглянуто еволюцію ливарного виробництва, сучасні методи одержання литих заготовок, класифікацію способів виробництва заготовок литтям, їх переваги та недоліки. Подано фундаментальні основи сучасного виробництва литих заготовок, раціональні варіанти їх виготовлення; обладнання, інструменти та технологічне оснащення для різних технологічних режимів і умов. Для перевірки отриманих знань запропоновано тестові завдання з кожного розділу посібника. Начальний посібник рекомендовано для здобувачів вищої освіти галузі знань 13 «Механічна інженерія», а також для інженерно-технічних працівників ливарної промисловостіThe manual «Technologies of Workpieces Manufacturing by Castings» provides knowledge regarding different foundry processes and their industrial importance. It is considered the modern techniques of processing raw materials by casting as an important stage of solving the tasks of designing technological processes for manufacturing the parts. The manual includes fundamentals of metal casting, the evolution of the foundry industry, basic casting techniques, the metal casting operations, methods of manufacturing the cast blanks; the most rational variants of their manufacturing; equipment, tools and machining attachments for making workpieces of machine elements and parts in different process specifications and conditions. Also focused on efficient design of casting runner, riser and gating system with minimal casting defects and solidification process. Multiple choice questions from each section of the manual are offered to test the acquired knowledge. Recommended for higher education seekers in 13 «Mechanical Engineering» majors, and can also be useful for engineering and technical specialists of foundry technologies in the mechanical engineering industryINTRODUCTION...7 1. EVOLUTION OF THE METAL CASTING INDUSTRY...8 Multiple Choice Questions...18 2. METAL CASTING AS A MANUFACTURING PROCESS...22 Multiple Choice Questions...33 3. METALS AND ALLOYS USED IN METAL CASTING...38 Multiple Choice Questions...54 4. CLASSIFICATION OF METAL CASTING PROCESSES...58 Multiple Choice Questions...62 5. FUNDAMENTALS OF METAL CASTING 5.1. Metal casting basics...64 5.2. Metal casting operations...73 5.3. Gases in metal casting...80 5.4. Metal casting design...82 Multiple Choice Questions...90 6. EXPENDABLE MOLD CASTING 6.1. Sand casting...129 6.2. Plaster mold casting...140 6.3. Ceramic mold casting...143 6.4. Shell molding...146 6.5. Vacuum casting...152 6.6. Expanded polystyrene casting...158 6.7. Investment casting Multiple ...162 Choice Questions...169 7. PERMANENT MOLD CASTING 7.1. Basic permanent mold casting...204 7.2. Vacuum permanent mold casting...213 7.3. Slush casting...216 7.4. Die casting...223 7.4.1. Hot chamber die casting...233 7.4.2. Cold chamber die casting...240 7.5. Pressure die casting...248 7.5.1. Low pressure die casting...253 7.5.2. High pressure die casting...260 7.5.3. Gravity die casting...270 7.6. Centrifugal casting...276 7.6.1. True centrifugal casting...283 7.6.2. Semi-centrifugal casting...288 7.6.3. Centrifuge casting...294 7.7. Squeeze casting...299 7.8. Continuous casting...307 7.9. Evaporative pattern casting...314 7.9.1. Lost foam casting...325 7.9.2. Full mold casting...331 7.10. Stir casting...337 7.11. Ingot casting manufacture...341 Multiple Choice Questions...346 8. CASTING DEFECTS 8.1. Casting microstructure...411 8.2. Casting defects and remedies... Multiple Choice Questions...427 9. COMPUTER SYSTEMS FOR CASTING PROCESSES SIMULATION...433 GLOSSARY...446 REFERENCES...48

Research and Technology 1995

This report selectively summarizes the NASA Lewis Research Center's research and technology accomplishments for fiscal year 1995. It comprises over 150 short articles submitted by the staff members of the technical directorates. The report is organized into six major sections: aeronautics, aerospace technology, space flight systems, engineering support, Lewis Research Academy, and technology transfer. A table of contents, an author index, and a list of NASA Headquarters program offices have been included to assist the reader in finding articles of special interest. This report is not intended to be a comprehensive summary of all research and technology work done over the past fiscal year. Most of the work is reported in Lewis-published technical reports, journal articles, and presentations prepared by Lewis staff members and contractors (for abstracts of these Lewis-authored reports, visit the Lewis Technical Report Server (LETRS) on the World Wide Web-http://letrs.lerc.nasa.gov/LeTRS/). In addition, university grants have enabled faculty members and graduate students to engage in sponsored research that is reported at technical meetings or in journal articles. For each article in this report, a Lewis contact person has been identified, and where possible, reference documents are listed so that additional information can be easily obtained. The diversity of topics attests to the breadth of research and technology being pursued and to the skill mix of the staff that makes it possible. For more information about Lewis' research, visit us on the World Wide web-http://www.lerc.nasa.gov

Fabrication of clog-free microfluidic cell isolation and solid-state light-emitting devices for biomedical applications

Over the past few decades, research and development on microfluidic devices, also referred to as lab-on-a-chip systems or microfluidic total analysis systems (TAS), have advanced quickly. There aren't many commercial success stories for microfluidic devices, despite the many advantages they offer, including improved analytical performance, decreased sample and reagent usage in the biomedical disciplines. From liquid biopsies, microfluidics has been used to filter out rare tumor cells from blood. Low flow rates and device clogs brought on by a single fluidic path function severely restrict processing. A novel technique was created employing multifunctional hybrid microposts with various features has effectively ensured high effective separation of rare cells from biological fluids. Furthermore, Solid-State perovskite material is synthesized, fabricated in 3D printed layers, and characterized for the need to be incorporated into fluorescence imaging of biological cells. Since effective imaging techniques are required to image the cells in a PDMS-based microfluidic device, the emission of the perovskite material shows positive signs as a fluorescent light source for identification of cells based on their emission of light.Includes bibliographical references

Automated liquid handling systems for microfluidic applications

Advances in microfluidic research have improved the quality of assays performed in micro-scale environments. Improvement of liquid handling techniques has enabled efficient reagent and drug use while minimising waste. The requirements for the applied techniques vary with applications and a custom integrated liquid handling solution was developed to accomplish some of these applications with minimal changes to the system. It is desirable to employ this technology to neuroscience research that requires a fluidic system that can test theories of reinforcement learning in neuronal cultures. An integrated system is therefore required to implement transport and manipulation of media and drugs loaded in a microfluidic device. One requirement for such an integrated system for liquid handling is a transport mechanism to deliver reagents and nutrients to cultures. A liquid flow control system is required to allow precise and timely control of flow rates through a microfluidic device. This can be extended to enable more sophisticated drug delivery approaches like gradient generation, spatial drug distribution and high temporal resolution of the drugs delivered. Another requirement for an integrated system is a liquid loading system that is capable of inserting specified drugs into the flow line. Such a loading system would allow any number of drugs to be loaded during an experimental process to the microfluidic device containing cells as part of an assay. The integration of these systems will allow researchers take advantage of the combined systems. Software development process should also be undertaken to improve the modularity of the integrated system so that hardware changes have marginal effects on the system operation. The project scope was the development of these liquid handling systems as well as their integration in hardware and software to enable their spatio-temporal drug delivery to neuronal cultures in microfluidic devices. The approach was to optimise performance of custom liquid handling system which was developed to realise fast flow rate changes within 1 second interval. Macro- and micro-scale solutions have been investigated in order to realise effective off-chip liquid loading capabilities. Emphasis has been placed on ease of use, modularity, rapid prototyping and precision. A commercial autoloader was identified as a starting point for sequential drug delivery. This was characterised for suitability and the constraints with this setup was used to identify additional requirements for the development of a novel sequential liquid injection system. The design process of the novel liquid injection system was unable to realise a working system due to mechanical and operational challenges encountered. A modular on-chip liquid manipulation system has been investigated and proposed to realise the sequential injection requirements. Rapid prototyping techniques that can promote ubiquitous microfluidic applications have been identified and verified. An integrated liquid manipulation system has been developed using the commercial autosampler that enables sequential loading of agonists into the microfluidic device as well as reliable chemical signalling of the loaded drugs by switching flow rates of the inputs to the device. This system will be beneficial towards research of other cell types within other research fields requiring similar functionality