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In this paper, firstly, the energy conservation equation of the cold side and the hot side of the precooler is written according to the energy conservation. Then the model of the precooler is established based on Matlab S-Function, and the model is simulated. The cold side helium mass flow is reduced to obtain the curve of the heat side temperature change, and the transfer function of the cold side...
Based on particle-in-cell (PIC) simulation, a robust method is developed to calculate varied loss-front velocity of long magnetically insulated transmission line (MITL) in pulse-propagating direction. In this method, the MITL is divided into several segments, and the loss front moves from one segment to the next one. Assumptions for this method include: 1) the interval between loss front and precursor...
A smart watch is one of the most popular wearable devices now. The end user cares about the electronic performance and safety. Along with the battery life and security, thermal safety is the most common concern. We show how to meet the ergonomic standard of user, predict the thermal performance on the typical scenarios. Certain thermal simulation software Flotherm or Icepack can be applied to the...
Time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) has higher spectral efficiency than standard cyclic prefix OFDM (CP- OFDM), which is achieved by using a known pseudorandom noise (PN) sequence to replace the classical CP. However, due to the interference between the PN sequence and the data block, the performance of TDS-OFDM degrades severely over fast fading channels...
Massive multiple-input multiple-output (MIMO) using a large number of antennas at the base station (BS) is a promising technique for the next-generation 5G wireless communications. It has been shown that linear precoding schemes can achieve near-optimal performance in massive MIMO systems. However, classical linear precoding schemes such as zero- forcing (ZF) precoding suffer from high complexity...
Conventional linear precoding schemes in massive multiple-input-multiple-output (MIMO) systems, such as regularized zero-forcing (RZF) precoding, have near-optimal performance but suffer from high computational complexity due to the required matrix inversion of large size. To solve this problem, we propose a successive overrelaxation (SOR)-based precoding scheme to approximate the matrix inversion...
This paper proposes a parametric channel estimation method for massive multiple input multiple output (MIMO) systems, whereby the spatial correlation of wireless channels is exploited. For outdoor communication scenarios, most wireless channels are sparse. Meanwhile, compared with the long signal transmission distance, scale of the transmit antenna array can be negligible. Therefore, channel impulse...
In this paper, we propose a new method for blind modulation detection based on detailed second order cyclostationary features for underwater acoustic communication. Due to the severe and fast varying Doppler shift and phase noise in the underwater acoustic communication channel, much shorter signal length can be used to detection the modulation scheme, leading to less accuracy in the modulation detection...
Orthogonal Frequency Division Multiplexing (OFDM) has been considered as a strong candidate for next generation high speed aerial vehicle communication systems. However, OFDM systems suffers severe performance degradation due to inter-carrier interference (ICI) in high mobility channel, if no ICI cancellation is performed. Traditionally, training symbols have been employed in one packet to help the...
Target detection is a surveillance problem of practical importance that is well suited to wireless sensor networks. In this paper, we study the target search via track-before-detect process for moving targets in large area utilizing a network of distributed sensor nodes. Specifically, we extend the track-before-detect process to heterogeneous sensors with imperfect communication links between the...
Services paths planning for Electric Power Communication Network (EPCN) is mainly designed by artificial pre-assignment and Dijkstra's algorithm. These algorithms commonly assign services on the shortest path to ensure the time delay. However, assigning too many services on one short line to reduce time delay may increase the risk. Therefore, to balance both the requirements of low-risk and low-delay...
It is well known that Orthogonal Frequency Division Multiplexing (OFDM) systems suffer from intercarrier interference (ICI) in mobile environment due to loss of orthogonality among subcarriers caused by Doppler shifts. There exist many ICI mitigation techniques in the literature to improve the performance of OFDM systems. However, most of the existing ICI mitigation techniques assume the OFDM transmission...
In recently developed cognitive radio network (CRN), the spectrum sharing leads to many uncertainties associated with the aggregate interference in the network. It is highly desired to build an interference model for such cognitive radio networks to express such uncertainties to quantify the effect of the interference on the primary network. However, existing interference models have not account for...
This paper describes how to meet the tourists' demands by using web crawlers, perceptual hashing, decision tree modeling and other technologies in city tourist attractions recommendation. The system makes the intelligent suggestions by using web crawlers to capture weather conditions for the next few days, and builds a decision tree according to the data base of users' feedbacks. It analyses the result...
Radio spectrum has become a precious resource, and it has long been the dream of wireless communication engineers to maximize the utilization of the radio spectrum. Dynamic Spectrum Access (DSA) and Cognitive Radio (CR) have been considered promising to enhance the efficiency and utilization of the spectrum. In current overlay cognitive radio, spectrum sensing is first performed to detect the spectrum...
In this paper, we implement and demonstrate an adaptive interference avoidance TDCS (Transform-domain Communication System) based cognitive radio via software defined radio implementation. By dynamically notching the occupied bands prior to applying IDFT, the designed cognitive radio communicates without interference to primary users and from primary users, as well as provides coexistence between...
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