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with the development of electronic information technology, the heating problem in microwave components is becoming more and more important. Reducing dielectric loss is an effective way to reduce component heat. Bi1−xYxFeO3 (x=0.02, 0.04, 0.06, 0.08) ceramics were synthesized by traditional state solid method, and the effects of Y3+ ions on magnetic and dielectric properties were studied. The XRD results...
Magnetic and dielectric properties of multiferroic (1−x)BiFeO3−xBaFe12O19 (x=0.03, 0.05, 0.07, 0.09 wt%) solid solution synthesized by state solid were investigated. Morphology of the sample is determined by SEM, indicating that the grain has been shrink, and all samples have been irregular. With increasing of BaFe12O19, saturation magnetization increased from 0.07 to 0.7 emu/g, and coercivity increased...
In this research, a low cost control system of active magnetic bearings (AMB) has been designed and implemented using LabVIEW Interface for Arduino (LIFA). This study consists of analog signals acquisition, converting the analog signals into the digital signal (ADC), digital data processing, drawing real-time curve and historical curve of signals, pulse-width modulated (PWM) drive and PID control...
A hybrid foil-magnetic bearing (HFMB) is a combination of the gas foil bearing (GFB) and the magnetic bearing (MB), which takes advantages of each individual bearing and compensates for their inherent weaknesses each other. However, control of the HFMB is different from that of the AMB considering the varying dynamic stiffness and damping coefficients of the GFB. This paper presents an adaptive control...
Large-scale multiple-input multiple-output (MIMO) system with tens to hundreds of antennas is getting increasing attention for its very high spectral efficiency and energy efficiency. However, for frequency division duplexing (FDD) system, the cost of CSIT feedback becomes a bottleneck with the BS antennas increasing. To reduce the cost of the downlink training and the CSIT uplink feedback, joint...
Large-scale multiple-input multiple-output (MIMO) system with tens to hundreds of antennas is getting increasing attention for its very high spectral efficiency and energy efficiency. However, for frequency division duplexing (FDD) system, the cost of CSIT feedback becomes a bottleneck with the BS antennas increasing. To reduce the cost of the downlink training and the CSIT uplink feedback, joint...
The contact interfaces for the rod-fastened rotor of a heavy-duty gas turbine rotor were analyzed and classified into three kinds. In order to predict the effects of contact interfaces on the rotor dynamic characteristics of the heavy-duty gas turbine generator set, the torsional characteristics of the contact segments were studied firstly. The piecewise bilinear torsional deformation model for the...
In this paper, a novel self-interference (SI) suppression scheme based on Dempster-Shafer (D-S) evidence theory is proposed to cancel self-interference in two-way full-duplex (FD) MIMO relay. D-S evidence theory can appropriately characterize uncertainty and make full use of multiple evidence source information by Dempster's combination rule to obtain reliable decisions. Instead of traditional spatial-domain...
The spectral performance parameters of hyper-spectral imaging spectrometer include the spectral calibration parameter and the radiometric calibrati on parameter. Accurate calibration of these parameters is the basic premise of the quantitative application of hyper-spectral data. The spectral calibration is used to determine the central wavelength, spectral width, and the radiometric calibration is...
The advent of petascale computing has introduced new challenges (e.g. Heterogeneity, system failure) for programming scalable parallel applications. Increased complexity and dynamism in science and engineering applications of today have further exacerbated the situation. Addressing these challenges requires more emphasis on concepts that were previously of secondary importance, including migratability,...
Currently deployed petascale supercomputers typically use toroidal network topologies in three or more dimensions. While these networks perform well for topology-agnostic codes on a few thousand nodes, leadership machines with 20,000 nodes require topology awareness to avoid network contention for communication-intensive codes. Topology adaptation is complicated by irregular node allocation shapes...
Fine-grained communication in supercomputing applications often limits performance through high communication overhead and poor utilization of network bandwidth. This paper presents Topological Routing and Aggregation Module (TRAM), a library that optimizes fine-grained communication performance by routing and dynamically combining short messages. TRAM collects units of fine-grained communication...
An analytical model is proposed using the d/q-axis model to estimate the maximum output power of the high speed permanent magnet synchronous generator (PMSG) and corresponding current, power-angle, etc. An experimental phenomenon that a 100kW 45000rpm PMSG unable to generate rated power is analysed using the analytical model. Then the rotor structure is improved according to the analytical results...
The rotordynamic characteristics of a simulated rotor system supported on gas foil bearings was investigated, which has a rated speed of 24 krpm. A test rig was established and assembled to simulate the operating performance of the rotor system for a microturbine. The compliant gas foil journal and thrust bearings were designed to support the rotor. The rotor system was driven by high pressure gas...
For the ultra high speed PM rotor, a metallic sleeve is usually interference fitted onto a cylinder or ring shaped PM to against the huge centrifugal force. The initial interference hinges not only on the loose of the rotor, but also strongly on the strength of the PM and the sleeve. In order to determinate the initial interference, this paper proposes an analytical model of stress/displacement field...
With the development of Internet of Things, the timely and fast storage of various types of stream data is becoming the urgent problem to the Internet of Things applications. Facing the arriving stream data continuously, data stream storage system must store the results persistently in a timely way. After analyzing the characteristic of stream data of the transport monitoring system, we propose a...
Gas Foil Bearings (GFBs) are self-acting hydrodynamic bearings and potential alternatives to rolling element bearings for high speed applications. In order to increase load capacity, the assembly preload is often added to GFBs now. Firstly, for multi-leaf GFBs with assembly preload, this paper presents a method to fabricate the bearings with assembly preload, and the precision of the shape of the...
IBM Blue Gene/Q is the next generation Blue Gene machine that can scale to tens of Peta Flops with 16 cores and 64 hardware threads per node. However, significant efforts are required to fully exploit its capacity on various applications, spanning multiple programming models. In this paper, we focus on the asynchronous message driven parallel programming model -Charm++. Since its behavior (asynchronous)...
Achieving good scaling for fine-grained communication intensive applications on modern supercomputers remains challenging. In our previous work, we have shown that such an application -- NAMD -- scales well on the full Jaguar XT5 without long-range interactions; Yet, with them, the speedup falters beyond 64K cores. Although the new Gemini interconnect on Cray XK6 has improved network performance,...
Gemini, the network for the new Cray XE/XK systems, features low latency, high bandwidth and strong scalability. Its hardware support for remote direct memory access enables efficient implementation of the global address space programming languages. Although the user Generic Network Interface (uGNI) provides a low-level interface for Gemini with support to the message-passing programming model (MPI),...
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