104 research outputs found
Prediction of shielding effectiveness of cementgraphite powder using artificial neural network
No full textThis paper presents the method to predict the shielding effectiveness of cement powder
mixed with different amount of graphite powder. Cement mixed with different percentage
of graphite is prepared. Their dielectric constant and loss tangent are measured based on
the transmission/reflection technique using APC7 connector. The measured data is fed into
Artificial Neural Network (ANN) for training. When the training process is completed the
neural network is used to predict the dielectric constant and loss tangent of cementgraphite
mixture that contains different amount of graphite. The comparison shows that
the trained neural network is very successful to predict the dielectric constant and loss
tangent of cement-graphite mixture. The proposed graphical user interface has made the
process of shielding effectiveness prediction becomes more user friendly especially for
those designers who are not familiar with the analytical calculation of shielding
effectiveness and dielectric measurement
Equivalent wire model and travelling wave mode method to analyse the radiated emission of a bent microstrip line
No full textNowadays, expeditious developments in the electrical and electronic territory due to
endless demands from the markets have driven the operation frequency of the system
into the gigahertz region. This had evolved into a more effectual-performance
system, but also inflicts a lot of difficulties to the designers, for examples
Electromagnetic Interference (EMI) problem and Signal Integrity (SI) issue. The
integrity of circuit layout is inevitably compromised by bifurcated traces for
examples T -junctions, Y -junctions, right-angle bends or left-angle-bends and steps
planar transmission lines in order to fulfil the needs of a denser printed circuit
boards. However, bifurcation often induces impedance mismatching resulting in
reflection, radiated emission and power loss. This research is to investigate the
radiated emission of 0°,45° and 90° bent microstrip lines by using an analytical
fODnulation followed by computer simulation and experimental measurements for
validation purposes. The novelty of this research is the implementation of travelling
wave mode (TWM) method on bent microstrip line by adopting the equivalent wire
model. The reliability of the formulation is proven from the agreement between the
analytical results and computer simulation, especially in predicting the E¢
component. The analytical results clearly showed the significance of the bent in
altering the radiation pattern of the microstrip line. Increasing the operating
frequency and microstrip's width tend to produce more emission. One of the electric
field components, Eo is almost symmetrical with respect to the bent angle/2 line on
the plane of the microstrip line, while the E¢ component radiates strongly into the
bent angle + bent anglel2 direction. The magnetic field on the bent microstrip line
experiences an abrupt change at the location of the bent. This change becomes
apparent as the bent angle increases. Future work should focus on improving the
analytical fornmlation so that it can predict the Eo component with higher accuracy.
FurtheDnore, effort can also be made on generating algorithm which takes into
consideration the composite electric field radiation of all the bents on a practical
printed circuit board
Shielding effectiveness of concrete with graphite fine powder in between 50MHz to 400MHz
No full textDielectric Characterization Based On Complementary Split-Ring Resonator
No full textMaterial characterization method based on radio frequency and microwave measurements is highly demanded. The dielectric properties is very important for electronic circuit design, food industry, medicine and health care. In this work, a complementary split-ring resonator (CSRR)-based sensor employed in the ground plane is proposed for dielectric measurement. This method enable the determination of both relative permittivity and relative permeability at the same time as well as simple sample preparation process. This project focuses on the design, simulation and the prediction formulae of the CSRR. This CSRR is resonating at 2.477 GHz with a quality factor of 128.91 in unloaded condition. Basically, there are shifting in the resonance frequency and the change of the quality factor when dielectric material is placed at the highest intensity of electric and magnetic fields in separate zones. Four predicted formulas are proposed, which they are depend on the dielectric constant, real permeability, normalized resonance frequency, inverse normalized quality factor, electric loss tangent and magnetic loss tangent of the materials. The prediction formulas are used to measure the permittivity and permeability of FR-4, Polyimide, and self-defined material. Based on the comparison, the percentage error between calculated result and reference data are 10% and 4.1% for electric and magnetic loss tangent respectively. The maximum percentage error in dielectric constant and real permeability are 4.5% and 4.29% respectively. Based on the percentage of error, it is convincing that the prediction formulas are reliable for dielectric measurement. Future work of this project should focus on verification of its actual performance through experimental measurement
Magnetic and electric field radiation of bent microstrip line using Hertzian dipole method
No full textVending Machine for Enhancing Healthcare Access
No full textThis project addresses challenges in pharmacy access and feedback mechanisms for vending machine utilization by developing an advanced healthcare vending system. The system integrates RFID technology and an Arduino Mega microcontroller to enable secure dispensing and a conceptual RFID-based payment system. Additionally, an MIT App was developed to provide customer assistance. The methodology involved designing and assembling the vending machine\u27s mechanical and electrical components, programming the Arduino Mega, and testing the system. Results demonstrated robust RFID tag detection at 100% within 1.0 cm, declining accuracy at greater distances, and product vending accuracy ranging from 70% to 90% across slots. These findings highlight the potential of the system to enhance healthcare accessibility through reliable dispensing technology. Future improvements include IoT-based real-time inventory tracking for stock and expiration monitoring and implementing a Telegram bot for intelligent inventory management.
Optimization under uncertainty in radiation therapy
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 175-182).In the context of patient care for life-threatening illnesses, the presence of uncertainty may compromise the quality of a treatment. In this thesis, we investigate robust approaches to managing uncertainty in radiation therapy treatments for cancer. In the first part of the thesis, we study the effect of breathing motion uncertainty on intensity-modulated radiation therapy treatments of a lung tumor. We construct a robust framework that generalizes current mathematical programming formulations that account for motion. This framework gives insight into the trade-off between sparing the healthy tissues and ensuring that the tumor receives sufficient dose. With this trade-off in mind, we show that our robust solution outperforms a nominal (no uncertainty) solution and a margin (worst-case) solution on a clinical case. Next, we perform an in-depth study into the structure of different intensity maps that were witnessed in the first part of the thesis. We consider parameterized intensity maps and investigate their ability to deliver a sufficient dose to the tumor in the presence of motion that follows a Gaussian distribution. We characterize the structure of optimal intensity maps in terms of certain conditions on the problem parameters.(cont.) Finally, in the last part of the thesis, we study intensity-modulated proton therapy under uncertainty in the location of maximum dose deposited by the beamlets of radiation. We provide a robust formulation for the optimization of proton-based treatments and show that it outperforms traditional formulations in the face of uncertainty. In our computational experiments, we see evidence that optimal robust solutions use the physical characteristics of the proton beam to create dose distributions that are far less sensitive to the underlying uncertainty.by Timothy Ching-Yee Chan.Ph.D
Low Loss THz Waveguides and Its Potentials towards 6G Communication: A Brief Chronicle Review
No full textAdvancement in technology has opened the doors for the terahertz (THz) frequency range to be applied in different fields for various applications. The future communication technology, especially 6G, will also intend to utilize the THz frequency band due to its large bandwidth that has the capabilities to achieve a high data rate. Great losses are presented in the early research into terahertz transmission medium. It is critical to design an appropriate waveguide that can integrate the THz waves into the system efficiently with minimum loss and provides the ease of transmission of data and overcomes the free space loss issues. Communication, sensing, and other application parameters are highly affected by transmission losses; therefore, low transmission loss and dispersion loss waveguide designs are required for proper utilization. In this paper, the review on reduction in the transmission loss in different types of waveguides operating at the Terahertz frequency range is studied. The design and the experimental setup for several classes of THz waveguides for minimizing transmission loss are also discussed. The review study shows that these waveguides can be a promising transmission medium for future 6G communicatio
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