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To reduce the cost of the Nd–Fe–B magnets, the Ce element was suggested to be used as a replacement of Nd element. In this paper, nanocrystalline (Ce1–xNdx)16Fe78B6 ($x = 0$ –0.7) alloys were prepared by melt spinning. The X-ray diffraction (XRD) results indicate that the alloys are composed of (NdCe)2Fe14B (2:14:1) phase and (CeNd)Fe2 (1:2) phase for 0 < 0.6, and the 1:2 phase was replaced by...
In this letter, an optimal power allocation scheme for energy efficiency (EE) maximization with low complexity in 5G downlink multiuser systems is presented. The optimal power allocation is obtained in two steps. The first step is to find the power scheme to maximize the geometric mean of weighted average channel gains corresponding to any fixed total dynamic power. The second step to obtain the optimal...
A novel refractive index (RI) sensing system with improved resolution based on a microwave photonics filter (MPF) is proposed and experimentally demonstrated. The sensing probe used for RI measurement is a microfiber Bragg grating. We use the frequency interrogation scheme (different from the traditional wavelength demodulation method) for resolution improvement of RI detection. The frequency shift...
High sensitivity biological sample measurement has been achieved by using a 12° tilted fiber Bragg grating (TFBG). Human acute leukemia cells with different intracellular densities whose refraction index (RI) ranging from 1.3342 to 1.3344 were clearly discriminated by using the differential spectral measurement of the cutoff resonance between two orthogonal polarizations, combining with a temperature...
A compact fiber torsion sensor, in which a short section of polarization-maintaining (PM) fiber stub containing a normal straight fiber Bragg grating (FBG) is spliced to another single-mode fiber without any lateral offset, is proposed and experimentally demonstrated. Two well-defined resonances (orthogonal-polarimetric FBG core-modes) with ∼0.5 nm wavelength separation have been achieved in reflection...
Philips has introduced the world's first whole body sequential PET/MR system. We present the current status of MR-based attenuation correction (MRAC) technique. MRAC consists of MR image acquisition, segmentation, truncation compensation (TC), μ-value assignment, as well as correction for patient table and RF coils. These components have been described last year; this paper focuses on updates of the...
In this paper MR-based attenuation method was implemented for a clinical whole-body PET/MR system. While awaiting future clinical evaluation, the algorithm seems promising from preliminary patient data evaluation, from both qualitative PET image quality and quantification accuracy. While the 3-segment MRAC resembles the results from short PET transmission scans, future work will be to implement and...
A sequential PET/MR system like Philips Gemini TF PET/MR system generates attenuation correction map from an MR image instead of a CT or transmission image for PET reconstruction. One problem in MR-based attenuation correction is that the MR table and coils are invisible in MR images but they may contain high density materials which have to be compensated for attenuation. This work investigates the...
The quality of service (QoS) support for multimedia communications faces a big challenge in a fading wireless network. On one hand, conventional automatic repeat request (ARQ) schemes are not effective for small-scale fading channels with correlated errors due to consecutive retransmission failures. On the other hand, large-scale fading due to propagation loss or shadowing severely limits transmission...
This work presents the application of a quantitative magnetic resonance imaging (MRI) technique in stereotactic deep-brain neurosurgery planning procedures. The high spatial resolution T1 and T2 maps acquired using this imaging method have been normalized to the standard CJH-27 brain coordinate system and integrated into a neurosurgical visualization and navigation system to improve the accuracy...
Summary form only given. In summary, we have successfully demonstrated a variety of methods to dramatically increase the bandwidth of Ti:sapphire chirped-pulse laser amplification systems. These methods have been used to generate amplified pulses as short as 18 fs. Additionally, we have simultaneously amplified and compressed two femtosecond pulses separated by as much as 100 nm in wavelength.
Summary form only given. In 1992, it was demonstrated that hard X-rays can be produced in the high-intensity, >10/sup 18/ W/cm/sup 2/, focus of a relatively low energy, /spl sim/40 mJ, ultrashort pulse laser system. Measurements of X-ray yield through various filter materials provided a crude spectrum of the X-rays and indicated that the majority of the X-ray flux was at energies suitable for diagnostic...
Summary form only given. In this paper, we present results of a three-stage Ti:sapphire laser amplification system that is designed to produce 1J pulses of 15 fs in duration. To date, the first two stages of amplification have produced 18 fs, 4 TW pulses at a repetition rate of 50 Hz and an average power 4 W. To our knowledge, these intermediate results represent the shortest terawatt pulses, the...
This paper presents a new approach to the position and velocity control of a manipulator by using the adaptive (self-tuning) controllers. The complicated model of a manipulator system is modeled by a set of time varying difference equations. The parameters of the system are determined by an on-line recursive algorithm based on the least squares error criterion. An adaptive controller is designed on...
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