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Lu Y.,China Unicom | Yang N.,Wireless Industrial Technologies, Inc. | Dai H.,North Carolina State University | Wang X.,Beijing University of Posts and Telecommunications
IEEE Transactions on Vehicular Technology | Year: 2012

In this paper, we propose new opportunistic decode-and-forward (DF) relaying with beamforming for multirelay networks, where an N s-antenna source communicates with an N d-antenna destination with the aid of N parallel single-antenna relays. Among these relays, only one relay that correctly decodes the signal from the source and has the highest instantaneous signal-to-noise ratio (SNR) to the destination is selected for transmission. The source employs maximum ratio transmission (MRT) to transmit, whereas the destination performs maximum ratio combining (MRC) to the received signals. To examine the benefits of the proposed scheme, we first derive the exact outage probability for independently but nonidentically distributed (i.n.i.d.) two-wave with diffuse power (TWDP) fading channels. We then derive an easy-to-compute expression for the exact outage probability to reduce computational cost. Our results encompass Rayleigh and Rician fading as special cases. We further derive a compact expression for the asymptotic outage probability, which characterizes two factors governing the network performance at high SNRs, i.e., the diversity order and the array gain. We demonstrate that our scheme preserves the maximum diversity order of N × min{N s,N d}. Additionally, we derive the optimal power allocation factor, which provides a practical design rule to optimally distribute the total transmission power between the source and the selected relay to minimize the outage probability. © 1967-2012 IEEE.


Lutzerath A.,TRIMET Aluminium SE | Evans J.W.,Wireless Industrial Technologies, Inc. | Victor R.,Wireless Industrial Technologies, Inc.
TMS Light Metals | Year: 2014

Since early 2012, individual anode currents of one Hall-H&oult pot at TRIMET, Hamburg, have been monitored using a system that measures the currents by sensing the magnetic fields produced by the anode currents. The system reports all anode currents every second, as well as the pot voltage. Data are transmitted wirelessly from the pot to a receiving computer near the pot for processing and onward transmission to the TRIMET network as well as to WIT in California. Interactive real-time plots of individual anode currents are available to engineers and others at both locations. The paper summarizes the difficulties overcome in the initial stages of the installation and displays representative plots of currents before and during anode effects, after anode changes, current interruptions etc. Some thoughts are provided on the value of making individual anode current measurements. Copyright © 2014 by The Minerals, Metals & Materials Society.


Zheng L.,Wireless Industrial Technologies, Inc.
Proceedings of the SICE Annual Conference | Year: 2010

This paper describes the resent industrial wireless sensor network technologies for process automation. It explains expected use cases, applications and technical requirements for the industrial wireless sensor networks. It introduces the trend of the industrial wireless communications standardization such as WirelessHART and ISA SP100.11a. © 2010 SICE.


Urata N.,Wireless Industrial Technologies, Inc. | Evans J.W.,Wireless Industrial Technologies, Inc.
TMS Light Metals | Year: 2010

A couple of previous papers have suggested that the current distribution in a pot can be determined by measuring magnetic fields, e.g. the distribution of current among the anode rods can be found by placing a magnetic field sensor next to each rod. Because the current distribution can have a significant effect on pot performance, the suggestion is worth analyzing and this has been done by mathematical models in the present paper. One important aspect of such measurements is the effect of fields generated by other currents on the measurement of a particular current, e.g. the effect of currents in adjacent anode rods on the measurement for one rod. It is shown that, with the use of a sufficient number of sensors, it should be possible to de-convolute individual anode currents, and other currents, from the measured field values.


Yang A.,Beijing Institute of Technology | Fei Z.,Beijing Institute of Technology | Yang N.,Wireless Industrial Technologies, Inc. | Yang N.,University of New South Wales | And 2 more authors.
IEEE Transactions on Vehicular Technology | Year: 2013

In this paper, we analyze the symbol error rate (SER) of space-time network coding (STNC) in a distributed cooperative network over independent but not necessarily identically distributed (i.n.i.d.) Nakagami-m fading channels. In this network, multiple sources communicate with a single destination with the assistance of multiple decode-and-forward (DF) relays. We first derive new exact closed-form expressions for the SER with M-ary phase-shift keying modulation (M-PSK) and M-ary quadrature-amplitude modulation ( M-QAM). We then derive new compact expressions for the asymptotic SER to offer valuable insights into the network behavior in the high signal-to-noise ratio (SNR) regime. Importantly, we demonstrate that STNC guarantees full diversity order, which is determined by the Nakagami-m fading parameters of all the channels but independent of the number of sources. Based on the new expressions, we examine the impact of the number of relays, relay location, Nakagami-m fading parameters, power allocation, and nonorthogonal codes on the SER. © 1967-2012 IEEE.


Ni W.,Wireless Industrial Technologies, Inc. | Collings I.B.,Wireless Industrial Technologies, Inc. | Liu R.P.,Wireless Industrial Technologies, Inc.
IEEE Transactions on Vehicular Technology | Year: 2012

Fixed relay networks will be an integrated component of future International Mobile Telecommunications (IMT)-Advanced. In this paper, we propose a new approach to relay handover and link adaptation. Our approach is built on a new Markov chain model (MCM) that comprehensively characterizes different relay protocols and quantifies their quality-of-service (QoS) measures, such as packet drop rate and latency, and spectral efficiency. Our relay handover and link adaptation scheme combats channel fluctuations while satisfying QoS requirements. It also accommodates multiple relay stations, supports multiplexing and diversity, and copes with mutually related and time-dependent transmissions. Analytical results, which were validated by simulations, show that our scheme can reduce the packet loss by up to three orders of magnitude. It also decreases the packet delay by up to 18% and improves the throughput by up to 10%. © 2012 IEEE.


Bojarevics V.,University of Greenwich | Evans J.W.,Wireless Industrial Technologies, Inc.
TMS Light Metals | Year: 2015

A software application based on the full MHD model of the aluminium electrolytic production cell is used to predict the liquid metal surface instability in a commercial Trimet operated potline. The results are compared with the electric current distribution variation in time over the anodes obtained from the measurement of magnetic fields by wireless sensors. The model incorporating full 3d busbar configuration predicts a critical instability excitation frequency 0.0259 Hz, which compares to the measured frequency of 0.0254 Hz. The mathematical software permits to analyse the sensitivity to the pot individual features like ACD, anode loads, ledge shape, bottom wear and busbar irregularities. The ability to monitor continuously the electric current distribution to high accuracy helps to control disturbances and to visualise the cell interior with the help of this numerical tool.


Yang N.,Wireless Industrial Technologies, Inc. | Yeoh P.L.,University of Melbourne | Elkashlan M.,Queen Mary, University of London | Collings I.B.,Wireless Industrial Technologies, Inc. | Chen Z.,Wireless Industrial Technologies, Inc.
IEEE Transactions on Vehicular Technology | Year: 2012

We propose and analyze two multiple-input-multiple-output (MIMO) two-way relaying schemes with an amplify-and-forward protocol in Nakagami-m fading channels, where multi-antenna sources communicate via a single-antenna relay. Specifically, we present a new framework for the comparative analysis of beamforming and antenna selection with nonidentical fading parameter m in the two source-relay links. To facilitate the comparison, we derive new exact, approximate, and asymptotic expressions for the sum symbol error rate (SSER) with M-ary phase-shift keying ( M-PSK) and M-ary quadrature amplitude modulation (M-QAM). Based on the asymptotic SSER, we prove that beamforming and antenna selection have the same diversity order. The diversity order is dominated by the weaker source-relay link, which is determined by the product of the number of source antennas and the fading parameter. We proceed to characterize the fundamental difference between the two schemes in terms of their array gains and average signal-to-noise ratios (SNRs). To obtain further insights, we address the key question of How to allocate the total transmit power such that the SSER is minimized? Our answer is given in the form of new concise expressions for the power-allocation factor that optimally distributes the total transmit power between the sources and the relay. A pivotal conclusion is reached that antenna selection offers the same SSER as beamforming when the source in the weaker link is equipped with a single antenna. © 1967-2012 IEEE.


Grant
Agency: Environmental Protection Agency | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 70.00K | Year: 2010

There are 315 to 458 million metric tons of CO2 (or equivalents) emissions per year due to primary aluminum production, of which 21 to 31 million metric tons are estimated to be produced in the United States. In part, this is due to the enormous electrical energy consumption entailed:  548,350 gigawatt hours worldwide (more than the electricity consumed by the whole of Germany), and the energy inefficiency of primary aluminum production (only 40-45% energy efficiency). It also is due to the emission of polyfluorinated hydrocarbons (PFCs). PFCs are more pernicious than CO2 in their impact on global warming with a global warming potential of 6,500 – 9,200 that of CO2. These PFCs are emitted by the large electrolytic cells in aluminum smelters at a level equivalent to 0.7 tons of CO2 equivalents per ton of aluminum produced. PFCs are emitted mainly during an upset condition of the cells known as an “anode effect”. These anode effects are marked by a large increase in cell voltage; methods are available for their quenching, but only after the excursion of cell voltage is detected, and typical effects last around 2 minutes. A typical aluminum plant, with a few hundred cells, would experience on the order of 100 anode effects per day. An alternative method of detecting anode effects has been investigated in prior work at Wireless Industrial Technologies (WIT). Hall effect sensors, connected to wireless transceivers, were used to tract the currents passing through individual anodes. Preliminary results indicated that the “signature” on an incipient anode effect was discernible in the anode currents approximately 1 minute before the cell voltage increase, providing an opportunity for earlier quenching of the effect or, perhaps, avoidance of the anode effect. In addition, measurement of individual anode currents has been shown by WIT to provide a means of detecting cells, which otherwise are performing below par (“noisy” cells or shorted cells) and thereby provides a further opportunity for reduction of greenhouse gas (GHG) emissions by reduction in electrical energy consumed per ton of aluminum produced. This project will allow WTI to carry the technology to the next stage:  demonstration of technical viability and potential benefits on all anodes of one cell of a primary aluminum plant.  Potential commercial applications are in the world aluminum industry. Projected gross revenues for WIT at Year 5 are $24 million with deployment completed at 21 of the world’s 200 primary aluminum plants.


Grant
Agency: Environmental Protection Agency | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 70.00K | Year: 2010

There are 315 to 458 million metric tons of CO2 (or equivalents) emissions per year due to primary aluminum production, of which 21 to 31 million metric tons are estimated to be produced in the United States. In part, this is due to the enormous electrical energy consumption entailed:  548,350 gigawatt hours worldwide (more than the electricity consumed by the whole of Germany), and the energy inefficiency of primary aluminum production (only 40-45% energy efficiency). It also is due to the emission of polyfluorinated hydrocarbons (PFCs). PFCs are more pernicious than CO2 in their impact on global warming with a global warming potential of 6,500 – 9,200 that of CO2. These PFCs are emitted by the large electrolytic cells in aluminum smelters at a level equivalent to 0.7 tons of CO2 equivalents per ton of aluminum produced. PFCs are emitted mainly during an upset condition of the cells known as an “anode effect”. These anode effects are marked by a large increase in cell voltage; methods are available for their quenching, but only after the excursion of cell voltage is detected, and typical effects last around 2 minutes. A typical aluminum plant, with a few hundred cells, would experience on the order of 100 anode effects per day. An alternative method of detecting anode effects has been investigated in prior work at Wireless Industrial Technologies (WIT). Hall effect sensors, connected to wireless transceivers, were used to tract the currents passing through individual anodes. Preliminary results indicated that the “signature” on an incipient anode effect was discernible in the anode currents approximately 1 minute before the cell voltage increase, providing an opportunity for earlier quenching of the effect or, perhaps, avoidance of the anode effect. In addition, measurement of individual anode currents has been shown by WIT to provide a means of detecting cells, which otherwise are performing below par (“noisy” cells or shorted cells) and thereby provides a further opportunity for reduction of greenhouse gas (GHG) emissions by reduction in electrical energy consumed per ton of aluminum produced. This project will allow WTI to carry the technology to the next stage:  demonstration of technical viability and potential benefits on all anodes of one cell of a primary aluminum plant.  Potential commercial applications are in the world aluminum industry. Projected gross revenues for WIT at Year 5 are $24 million with deployment completed at 21 of the world’s 200 primary aluminum plants.

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