Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 21 for “"parallel transmission"”.
-
Design algorithms for parallel transmission in magnetic resonance imaging
… design, implementation, and validation of parallel transmission technology in Magnetic Resonance Imaging (MRI). Novel algorithms are proposed which yield excellent excitation control, low RF power requirements, methods that extend to non-linear large-flip-angle excitation, as well as a new …
-
Magnetic resonance spectroscopic imaging using parallel transmission at 7T
… for new RF excitation hardware at 7T, so-called parallel transmission (pTx). The B1 homogeneity of the pTx excitations improved at least by a factor of 4 (measured by the normalized spatial standard deviations) compared to conventional single channel transmit systems. The first contribution of …
-
Numerical field simulation for parallel transmission in MRI at 7 tesla
Parallel transmission (pTx) is a promising improvement to coil design that has been demonstrated to mitigate B1* inhomogeneity, manifest as center brightening, for high-field magnetic resonance imaging (MRI). Parallel transmission achieves spatially-tailored pulses through multiple radiofrequency …
-
Parallel transmission for magnetic resonance imaging on a 9.4 Tesla Human System.
… very long and are impractical at high field. Parallel transmission, an emerging technique, makes it possible to design sufficiently short selective RF pulses for use in actual experiments. In this thesis, we demonstrate the first successful implementation of parallel transmission at an …
-
Design and implementation of multiple address parallel transmission architecture for storage area network
In this paper, we present a parallel transmission architecture for SAN. By using two schedulers on the destination and source addresses of packets, the load of multiple data flows between multiple devices can be balanced in an asymmetrical topology without using special hardware. The SAN …
-
Design of Multidimensional Large -Tip -Angle Radiofrequency Pulses for Parallel Transmission in Magnetic Resonance Imaging
… RF pulses (including both single-channel and parallel transmission) is first identified. Then, an alternative approach using a new class of spiral trajectories, termed the variable slew-rate spirals, is proposed to locally reduce B 1 amplitude of 2D RF pulses. The peak B1 reduction is achieved …
-
Mitigating Inhomogeneity in High-Field MRI Excitations: Arbitrary Waveform Optimization and Multiphoton Parallel Transmission (MP-pTx)
… elements surrounding the imaging region. Parallel transmission (pTx) mitigates this issue by employing multiple high-power, independently controlled transmit elements for more precise excitation control. However, since the wavelength of the applied radio waves is shortened in tissue, the …
-
Bilateral Ortohogonality Generative Acquisitions Method for Transmit Field Inhomogeneity Correction in Magnetic Resonance Imaging
… and multi-acquisition methods with and without parallel transmission systems have been demonstrated for addressing the transmit field inhomogeneity. While substantial improvements have been demonstrated with these methods, they can be limited to certain contrasts, require a library of pulses for …
-
NOVEL PARALLEL TRANSMIT SYSTEMS FOR MRI APPLICATIONS
… a new RF transmitter design is presented for MRI parallel transmissionapplications. Benchtop measurements and imaging experiments were performed withdifferent prototypes to prove system’s performance and potential advantages versus asystem based on conventional MRI RF hardware. The degrees of …
-
Fast simulation of E1, B1 and Specific Absorption Rate for 7T MRI with the use of graphical processors
… of much recent interest with developments of parallel transmission systems (pTx). While real-time estimates of local SAR over large volumes as well as SAR-constrained pTx RF design are highly desirable goals, it is both difficult to control and computationally demanding. Steady advances in …
-
Improved accuracy in susceptibility-based OEF measurements by mitigation of partial-volume effects via combined magnitude and phase reconstruction
… is developed and validated on in vivo data. Parallel Transmission (pTx) improves image quality and patient safety in high-field MRI. Unlike in single-channel MR excitation, an array of multiple excitation coils is used in pTx. However, coupling between these independent coils significantly …
-
Using Decoys as a Resiliency Mechanism in Spectrally Harsh DSA Environments
… interference away from the main source of transmission. Using either serial or parallel transmission (splitting the signal in time or splitting the signal's energy) with the decoy signals and the original signal can either maximize data throughput in a minimal-interference environment or …
-
Parallel transmit pulse sequence design for ultra-high field (7T) MRI
… solution to improve image homogeneity is parallel transmission (pTx). A pTx-enabled scanner has multiple independently-driven transmit channels, providing additional degrees of freedom for improved spatial and temporal control of the B+1 fields. This thesis aims to extend the methodology …
-
New Algorithms for Locating Faults in Series Capacitive Compensated Transmission Lines
… of the fault in a series capacitive compensated transmission line (SCCTL) plays an integral part in limiting the maintenance time following its tripping due to the occurrence of a permanent fault. Since, an SCCTL acts as a huge corridor of power, its outage will result in huge monetary losses …
-
Flexible and stretchable tactile sensing skins using microwave transmission lines and piezoresistive rubber
… a distributed sensor based on buried microwave transmission lines. Applied pressure deforms the silicone rubber dielectric, creating an impedance discontinuity that is used to determine the location and degree of deformation. Using an algorithm derived in this thesis, the sensor deformation can …
-
Control and operation of offshore wind farms connected with diode rectifier HVDC systems
… of offshore wind farms connected with two parallel transmission links, i.e. a DR-HVDC and a HVAC link, is investigated. A hierarchical control structure which contains primary, secondary and tertiary controls, is proposed to ensure reliable operation and smooth transition between DR-HVDC …
-
Medium access control design for all-IP and ad hoc wireless network
… main parts. The first part pursues a Prioritized Parallel Transmission MAC (PPTM) design for All-IP Wireless WAN. Two stages are used and each packet is with a priority level in PPTM. In stage 1, a pretransmission probability is calculated according to the continuous observation of the channel …
-
Design and analysis of energy-efficient media access control protocols in wireless sensor networks. Design and analysis of MAC layer protocols using low duty cycle technique to improve energy efficient and enhance communication performance in wireless sensor networks.
… efficiency. This is achieved by applying a parallel transmission concept on the communicating nodes. As a result, the overall efficiency of the channel contention mechanism increases and leads to higher throughput with lower energy consumption. Finally, this thesis proposed the use of the …
-
Excitation and readout Designs for high field spectroscopic imaging
… in magnetic resonance imaging RF excitation with parallel transmission (pTx) and magnetic resonance spectroscopic imaging (MRSI). Recent work in parallel RF excitation in MRI has been demonstrated to offer dramatically improved flexibility for manipulation of magnetization preparation for imaging …
-
Control Applications and Economic Evaluations of Distributed Series Reactors in Unbalanced Electrical Transmission Systems
… need to analyse and determine the adequacy of transmission capacity. There is a need for approaches to increase transmission system capacity without construction of new transmission facilities, all while assuring secure operation of the grid. New technologies can enhance efficiency and …
Page 1 of 2