Degrees of Freedom of Full-Duplex Multiantenna Cellular Networks

We study the degrees of freedom (DoF) of cellular networks in which a full duplex (FD) base station (BS) equipped with multiple transmit and receive antennas communicates with multiple mobile users. We consider two different scenarios. In the first scenario, we study the case when half duplex (HD) users, partitioned to either the uplink (UL) set or the downlink (DL) set, simultaneously communicate with the FD BS. In the second scenario, we study the case when FD users simultaneously communicate UL and DL data with the FD BS. Unlike conventional HD only systems, inter-user interference (within the cell) may severely limit the DoF, and must be carefully taken into account. With the goal of providing theoretical guidelines for designing such FD systems, we completely characterize the sum DoF of each of the two different FD cellular networks by developing an achievable scheme and obtaining a matching upper bound. The key idea of the proposed scheme is to carefully allocate UL and DL information streams using interference alignment and beamforming techniques. By comparing the DoFs of the considered FD systems with those of the conventional HD systems, we establish the DoF gain by enabling FD operation in various configurations. As a consequence of the result, we show that the DoF can approach the two-fold gain over the HD systems when the number of users becomes large enough as compared to the number of antennas at the BS.Comment: 21 pages, 16 figures, a shorter version of this paper has been submitted to the IEEE International Symposium on Information Theory (ISIT) 201

Vibration Modeling of Bladed Disks Subject to Geometric Mistuning and Design Changes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76928/1/AIAA-2004-1686-437.pd

Vertically aligned InGaN nanowires with engineered axial In composition for highly efficient visible light emission.

We report on the fabrication of novel InGaN nanowires (NWs) with improved crystalline quality and high radiative efficiency for applications as nanoscale visible light emitters. Pristine InGaN NWs grown under a uniform In/Ga molar flow ratio (UIF) exhibited multi-peak white-like emission and a high density of dislocation-like defects. A phase separation and broad emission with non-uniform luminescent clusters were also observed for a single UIF NW investigated by spatially resolved cathodoluminescence. Hence, we proposed a simple approach based on engineering the axial In content by increasing the In/Ga molar flow ratio at the end of NW growth. This new approach yielded samples with a high luminescence intensity, a narrow emission spectrum, and enhanced crystalline quality. Using time-resolved photoluminescence spectroscopy, the UIF NWs exhibited a long radiative recombination time (τr) and low internal quantum efficiency (IQE) due to strong exciton localization and carrier trapping in defect states. In contrast, NWs with engineered In content demonstrated three times higher IQE and a much shorter τr due to mitigated In fluctuation and improved crystal quality

A Compact, Generalized Component Mode Mistuning Representation for Modeling Bladed Disk Vibration

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76212/1/AIAA-2003-1545-961.pd

Compact, Generalized Component Mode Mistuning Representation for Modeling Bladed Disk Vibration

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76577/1/AIAA-13172-918.pd

Effect of sodium chloride, PGDO and Arabic gum in pollen liquid diluent on suspensibility of kiwi pollen

This study was conducted to develop the pollen liquid diluent suitable for the artificial pollination of kiwi. The pollen of ‘Matua’ kiwi was collected at 1 day before flowering. Five concentrations of sodium chloride (0, 50, 150, 250, and 350 mg․L-1), four concentrations of poly (glycolide-co-p-dioxanone) (0, 7, 14, and 21 mg․L-1), and four concentrations of arabic gum (0, 150, 350, and 550 mg․L-1) were tested on an absent condition of each component in the pollen liquid diluent. Twenty mg of pollen was distributed in beakers containing 10 mL of the pollen liquid diluent. Suspensibility of the pollen liquid diluent was measured by the sensory evaluation and particle size analyzer. The addition of sodium chloride in pollen liquid diluent was effectible for the suspensibility improvement and the promotion of pollen growth in kiwi pollen. The kiwi pollen in pollen liquid diluent could be suspended without damage in pollen germination at low concentration of poly (glycolide-co-p-dioxanone) (PGDO), which has been known as a safe surfactant. The addition of Arabic gum would be highly advantageous to the stabilization of the pollen liquid diluent without any contamination for pollen growth. Kiwi fruits were set and grown well by the artificial pollination using the pollen liquid diluent. Therefore, the use of the pollen liquid diluent in the artificial pollination of kiwi fruit should be an effective practice

Journal of Turbomachinery Technical Brief Predicting Blade Stress Levels Directly From Reduced-Order Vibration Models of Mistuned Bladed Disks

The forced vibration response of bladed disks can increase dra