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Full-Text Articles in Social and Behavioral Sciences
An Application Of Nonlinear Feature Extraction – A Case Study For Low Speed Slewing Bearing Condition Monitoring And Prognosis, Wahyu Caesarendra, Prabuono Buyung Kosasih, A K. Tieu, Craig Moodie
An Application Of Nonlinear Feature Extraction – A Case Study For Low Speed Slewing Bearing Condition Monitoring And Prognosis, Wahyu Caesarendra, Prabuono Buyung Kosasih, A K. Tieu, Craig Moodie
Faculty of Engineering and Information Sciences - Papers: Part A
This paper presents the application of four nonlinear methods of feature extraction in slewing bearing condition monitoring and prognosis: these are largest Lyapunov exponent, fractal dimension, correlation dimension, and approximate entropy methods. Although correlation dimension and approximate entropy methods have been used previously, the largest Lyapunov exponent and fractal dimension methods have not been used in vibration condition monitoring to date. The vibration data of the laboratory slewing bearing test-rig run at 1 rpm was acquired daily from February to August 2007 (138 days). As time progressed, a more accurate observation of the alteration of bearing condition from normal to …
Enhancing Mechanical Properties Of A Low-Carbon Microalloyed Cast Steel By Controlled Heat Treatment, Jingwei Zhao, Jeong Hun Lee, Yong Woo Kim, Zhengyi Jiang, Chong Soo Lee
Enhancing Mechanical Properties Of A Low-Carbon Microalloyed Cast Steel By Controlled Heat Treatment, Jingwei Zhao, Jeong Hun Lee, Yong Woo Kim, Zhengyi Jiang, Chong Soo Lee
Faculty of Engineering and Information Sciences - Papers: Part A
In the present work, detailed studies were made on the optimization of microstructure and mechanical properties of a low-carbon microalloyed cast steel through control of heat treatment conditions. Specimens were austenitized at temperatures ranging from 950 to 1200 °C for 2 h followed by different cooling methods (furnace, air and water). For analyzing the effect of holding time on mechanical properties, some cast specimens were austenitized at 1100 °C for different times followed by furnace cooling. After heat treatment, mechanical tests were employed to evaluate the room temperature Charpy impact and tensile properties. The characterization of complex precipitates formed during …
Work Hardening Behaviors Of A Low Carbon Nb-Microalloyed Si-Mn Quenching-Partitioning Steel With Different Cooling Styles After Partitioning, Jun Zhang, Hua Ding, Chao Wang, Jingwei Zhao, Ting Ding
Work Hardening Behaviors Of A Low Carbon Nb-Microalloyed Si-Mn Quenching-Partitioning Steel With Different Cooling Styles After Partitioning, Jun Zhang, Hua Ding, Chao Wang, Jingwei Zhao, Ting Ding
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, the strain hardening behaviors of a low carbon Nb-microalloyed Si–Mn quenching–partitioning (Q–P) steel were investigated. The microstructures were analyzed by the scanning electron microscope (SEM) and transmission electron microscope (TEM). Mechanical tests were used to evaluate the room temperature tensile properties of the steel. The work hardening behaviors of the tested specimens were analyzed using the Hollomon approach. The results showed that a two-stage work hardening behavior was observed during deformation processes. In the first stage, for the quenched samples, martensite deforms plastically and the hardening exponent decreased. For the air-cooled samples, however, the carbide-free ferrite deforms …
A Low Cost Soft Mapper For Turbo Equalization With High Order Modulation, Licai Fang, Qinghua Guo, Defeng (David) Huang, Sven Nordholm
A Low Cost Soft Mapper For Turbo Equalization With High Order Modulation, Licai Fang, Qinghua Guo, Defeng (David) Huang, Sven Nordholm
Faculty of Engineering and Information Sciences - Papers: Part A
In an MMSE based turbo equalization system, a soft mapper calculates the symbol mean and variance based on extrinsic Log-Likelihood-Ratios (LLRs) information coming from a Soft-Input Soft-Output (SISO) decoder. In this paper, we investigate the complexity of this module, and in particular, we employ a 3-segment linear approximation approach to calculate the mean and variance of data symbols from LLRs. For FPGA and VLSI implementation, we propose novel piecewise linear functions which map LLR to the mean and variance directly without the use of any two-variable-input multipliers. Simulation results for 16-QAM and 64-QAM show that the no multiplier approach has …
The Effect Of Chromium Addition On The Strain Ageing And Recrystallisation Behaviour Of Low Carbon Steel, Elena Pereloma, V Bata, Azdiar A. Gazder
The Effect Of Chromium Addition On The Strain Ageing And Recrystallisation Behaviour Of Low Carbon Steel, Elena Pereloma, V Bata, Azdiar A. Gazder
Faculty of Engineering and Information Sciences - Papers: Part A
The strain ageing and recrystallisation behaviour of conventional low carbon A06 steel was compared with those containing varying amounts of chromium (0.26, 0.52 and 0.74 wt.%). The results show that the A06 steel undergoes four stages of strain ageing: (i) the pinning by solute atoms of dislocations generated during pre-strain, (ii) the generation of fresh dislocations from grain boundaries, (iii) the onset of precipitation and, (iv) the inhibition of dislocation generation from grain boundaries due to pinning by carbon segregation. On the other hand, the chromium containing steels only exhibit the fIrst three stages of strain ageing. An approximately twofold …
Recrystallisation Behaviour Of Low Carbon Steel With And Without Addition Of Chromium, Azdiar A. Gazder, Vladimir Bata, Sujoy S. Hazra, Elena V. Pereloma
Recrystallisation Behaviour Of Low Carbon Steel With And Without Addition Of Chromium, Azdiar A. Gazder, Vladimir Bata, Sujoy S. Hazra, Elena V. Pereloma
Faculty of Engineering and Information Sciences - Papers: Part A
The effects of 0.74wt% Cr addition on the recrystallisation kinetics of low carbon (LC) steel was investigated using Vickers hardness testing, optical metallography and Electron Back- Scattering Diffraction (EBSD). Compared to the unalloyed steel, Cr addition significantly delays the time for recrystallisation and increases the JMAK pre-exponential factor (k) by an order of magnitude. During initial softening, EBSD returned similar orientations for nucleated and growing grain fractions in both steels. However with longer annealing times the micro-texture of recrystallised grains differs from their earlier counterparts. Overall, the effect of fine Cr carbides on grain boundary mobility in the LC-Cr steel …
Sensitization Behaviour Of 11-12% Cr Aisi 409 Stainless Steel During Low Heat Input Welding, Cornelis Janise Van Niekerk, Madeleine Du Toit
Sensitization Behaviour Of 11-12% Cr Aisi 409 Stainless Steel During Low Heat Input Welding, Cornelis Janise Van Niekerk, Madeleine Du Toit
Faculty of Engineering and Information Sciences - Papers: Part A
The study comprised of the investigation into the sensitization characteristics of AISI 409 titanium stabilized ferritic stainless steel during low heat input welding. AISI 409 is a fully ferritic stainless steel used in catalytic converters and tubing for automotive exhaust systems due to the supposition that sensitization does not occur during low heat input welding. Two plates of 2 and 4 mm were tested for sensitization during low heat input welding. The study confirmed that chromium carbide (M23C6) precipitation occurs on the grain boundaries in the heat-affected zone with consequent depletion of Cr adjacent to the …
Hardness And Microstructural Gradients In The Heat Affected Zone Of Welded Low-Carbon Quenched And Tempered Steels, W Pang, N Ahmed, D Dunne
Hardness And Microstructural Gradients In The Heat Affected Zone Of Welded Low-Carbon Quenched And Tempered Steels, W Pang, N Ahmed, D Dunne
Faculty of Engineering and Information Sciences - Papers: Part A
This paper concentrates on the form of the hardness gradient in the heat affected zones (HAZs) produced by submerged arc welding of two low-carbon Q & T steels. The results show unequivocally that the gradient differs from that found in steels of lower carbon equivalent in that the peak HAZ hardness is displaced from the grain coarsened heat affected zone (GCHAZ) into the grain refined heat affected zone (GRHAZ). Weld thermal cycle simulation has been used to confirm the results obtained from actual welds and to clarify the cause of this unexpected phenomenon.
Low-Complexity Ldpc Coded Bicm-Id With Orthogonal Modulations, S Che, S Tong
Low-Complexity Ldpc Coded Bicm-Id With Orthogonal Modulations, S Che, S Tong
Faculty of Engineering and Information Sciences - Papers: Part A
A low-complexity low density parity check (LDPC) coded bit-interleaved coded modulation with iterative decoding (BICM-ID) scheme with orthogonal modulations is proposed. With a novel mapping strategy of coded bits to symbols, the proposed scheme is equivalent to a generalised LDPC code with Hadamard constraints and thus orthogonal demodulation can be merged into the iterative LDPC decoding process, resulting in a simpler implementation and a lower computational complexity.
Low Temperature Graphene Growth, Shailesh Kumar, N Mcevoy, T. Lutz, G. Keeley, Nicholas Whiteside, Werner Blau, G. Duesberg
Low Temperature Graphene Growth, Shailesh Kumar, N Mcevoy, T. Lutz, G. Keeley, Nicholas Whiteside, Werner Blau, G. Duesberg
Faculty of Engineering and Information Sciences - Papers: Part A
We demonstrate the growth of graphene films on nickel substrates by chemical vapour deposition using acetylene at temperatures as low as 750 degrees celsius, opening a viable route for its scalable production. Raman spectroscopy was used to confirm defect-free mono and multilayer graphene at and above this temperature, and of defective graphene at lower temperatures. Atomic force microscopy and scanning electron microscopy performed directly on the films give an indication of graphene flake size, morphology and also the topography on substrate. An unexpected dependence of graphene thickness on precursor dwell time is reported. This together with low temperature growth suggests …
A Low-Complexity Iterative Channel Estimation And Detection Technique For Doubly Selective Channels, Qinghua Guo, Li Ping, Defeng (David) Huang
A Low-Complexity Iterative Channel Estimation And Detection Technique For Doubly Selective Channels, Qinghua Guo, Li Ping, Defeng (David) Huang
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, we propose a low-complexity iterative joint channel estimation, detection and decoding technique for doubly selective channels. The key to the proposed technique is a segment-by-segment processing strategy under the assumption that the channel is approximately static within a short segment of a data block. Through a virtual zero-padding technique, the proposed segment-by-segment equalization approach inherits the low-complexity advantage of the conventional frequency domain equalization (FDE), but does not need the assistance of guard interval (for cyclic-prefixing or zero-padding), thereby avoiding the spectral and power overheads. Furthermore, we develop a low-complexity bidirectional channel estimator, where the Gaussian message …
A Low-Complexity Iterative Channel Estimation And Detection Technique For Doubly Selective Channels, Qinghua Guo, Li Ping
A Low-Complexity Iterative Channel Estimation And Detection Technique For Doubly Selective Channels, Qinghua Guo, Li Ping
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, we propose a low-complexity iterative joint channel estimation, detection and decoding technique for doubly selective channels. The key is a segment-by-segment frequency domain equalization (FDE) strategy under the assumption that channel is approximately static within a short segment. Guard gaps (for cyclic prefixing or zero padding) are not required between adjacent segments, which avoids the power and spectral overheads due to the use of cyclic prefix (CP) in the conventional FDE technique. A low-complexity bi-directional channel estimation algorithm is also developed to exploit correlation information of time-varying channels. Simulation results are provided to demonstrate the efficiency of …
Evolution Analysis Of Low-Cost Iterative Equalization In Coded Linear Systems With Cyclic Prefixes, Xiaojun Yuan, Qinghua Guo, Xiaodong Wang, Li Ping
Evolution Analysis Of Low-Cost Iterative Equalization In Coded Linear Systems With Cyclic Prefixes, Xiaojun Yuan, Qinghua Guo, Xiaodong Wang, Li Ping
Faculty of Engineering and Information Sciences - Papers: Part A
This paper is concerned with the low-cost iterative equalization/detection principles for coded linear systems with cyclic prefixes. Turbo frequency-domain-equalization (FDE) is applied to systems that may contain the joint effect of multiple-access interference (MAI), cross-antenna interference (CAI) and inter-symbol interference (ISI). We develop an SNK-variance evolution technique for the performance evaluation of the proposed systems. Numerical results in various channel environments demonstrate excellent agreement between the predicted and simulated system performance. © 2008 IEEE.
Low-Complexity Iterative Detection In Multi-User Mimo Isi Channels, Xiaojun Yuan, Qinghua Guo, Li Ping
Low-Complexity Iterative Detection In Multi-User Mimo Isi Channels, Xiaojun Yuan, Qinghua Guo, Li Ping
Faculty of Engineering and Information Sciences - Papers: Part A
We propose a low-cost detection strategy for multi-user multiple-input-multiple-output (MIMO) systems with inter-symbol interference (ISI). The cyclic prefix (CP) technique is assumed. The proposed detection algorithm is derived in a very concise manner based on some elegant properties of circulant matrices. We show that multi-user detection and equalization can be carried out jointly and efficiently. © 2007 IEEE.
Atomic Observations Of Warm Rolled Low Carbon Steels Alloyed With Cr And P, E V. Pereloma, M K. Miller
Atomic Observations Of Warm Rolled Low Carbon Steels Alloyed With Cr And P, E V. Pereloma, M K. Miller
Faculty of Engineering and Information Sciences - Papers: Part A
Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005
Role Of Cr And P Additions In The Development Of Microstructure And Texture In Annealed Low Carbon Steels, E V. Pereloma, I B. Timokhina, A I. Nosenkov, J J. Jonas
Role Of Cr And P Additions In The Development Of Microstructure And Texture In Annealed Low Carbon Steels, E V. Pereloma, I B. Timokhina, A I. Nosenkov, J J. Jonas
Faculty of Engineering and Information Sciences - Papers: Part A
The recrystallisation behaviour of four warm rolled steels was investigated during annealing. The extra-low carbon (ELC) steel displayed the highest rate of recrystallisation, the steels with additions of chromium and phosphorus (LC(Cr)), (LC(Cr,P)) recrystallised at intermediate rates, while the interstitial-free (IF) steel exhibited the lowest rate. The additions of Cr and Cr/P increased the fraction of g-fibre in the annealing textures compared to that present in the ELC steel; this effect was particularly pronounced up to 50 % recrystallisation. After the completion of recrystallisation, the steel textures were characterized by a dominant g-fibre in the IF steel, while in the …
Reliability Of Higher Seeding Rates Of Wheat For Increased Competitiveness With Weeds In Low Rainfall Environments, D Lemerle, R D. Cousens, G S. Gill, S J. Peltzer, M Moerkerk, C E. Murphy, D Collins, Brian R. Cullis
Reliability Of Higher Seeding Rates Of Wheat For Increased Competitiveness With Weeds In Low Rainfall Environments, D Lemerle, R D. Cousens, G S. Gill, S J. Peltzer, M Moerkerk, C E. Murphy, D Collins, Brian R. Cullis
Faculty of Engineering and Information Sciences - Papers: Part A
Increasing crop competitiveness using higher seeding rates is a possible technique for weed management in low input and organic farming systems or when herbicide resistance develops in weeds. A range of wheat seeding rates were sown and resulted in crop densities between 50–400 plants/m2 (current recommendations are 100–150 plants/m2) in the presence and absence of annual ryegrass (Lolium rigidum Gaud.) in three wheat cultivars at nine experiments in southern Australia. Wheat densities of at least 200 plants/m2 were required to suppress L. rigidum and to a lesser extent increase crop yield across a wide range …
Widmanstatten Ferrite Plate Formation In Low-Carbon Steels, Dominic Phelan, Rian Dippenaar
Widmanstatten Ferrite Plate Formation In Low-Carbon Steels, Dominic Phelan, Rian Dippenaar
Faculty of Engineering and Information Sciences - Papers: Part A
The mechanism by which Widmanstätten ferrite plates nucleate and grow in low-carbon steels has been studied. In-situ laser scanning confocal microscopy (LSCM) observations, optical microscopy, and electron backscattered diffraction (EBSD) techniques have been used to characterize the relationship between grain boundary allotriomorphs and Widmanstätten ferrite plates. The issue of where Widmanstätten ferrite plates nucleate is one of some debate, with theories including morphological instability and sympathetic nucleation. Evidence has been found that supports the theory of a sympathetic nucleation mechanism being responsible for the formation of Widmanstätten ferrite plates. The EBSD measurements have shown that low-angle misorientations of between 5 …
Delta-Ferrite Recovery Structures In Low-Carbon Steels, Rian Dippenaar, Dominic Phelan
Delta-Ferrite Recovery Structures In Low-Carbon Steels, Rian Dippenaar, Dominic Phelan
Faculty of Engineering and Information Sciences - Papers: Part A
The development of delta-ferrite recovery substructures in low-carbon steels has been observed in-situ utilizing laser scanning confocal microscopy (LSCM). Well-developed sub-boundaries with interfacial energies much smaller than that of delta-ferrite grain boundaries formed following transformation from austenite to delta-ferrite on heating. It is proposed that transformation stresses associated with the austenite to delta-ferrite phase transformation generate dislocations that subsequently recover into sub-boundaries by a process of polygonization. Experimental evidence in support of this proposal was found in a ferritic stainless steel. Thermal cycling through the high-temperature delta-ferrite/austenite/delta-ferrite phase transformation leads to the development of a well-defined recovery substructure, which, in …
Low Temperature Synthesis Of Al-Aln Composites From A Nanostructure Made By Controlled Magneto-Ball Milling Of Al In Ammonia, Andrzej Calka, J I. Nikolov, G H. J Wantenaar
Low Temperature Synthesis Of Al-Aln Composites From A Nanostructure Made By Controlled Magneto-Ball Milling Of Al In Ammonia, Andrzej Calka, J I. Nikolov, G H. J Wantenaar
Faculty of Engineering and Information Sciences - Papers: Part A
The formation of an AlN compound in ball milled Al powder in ammonia was studied. In this work a magneto‐ball milling device with controlled ball movement was used. The end milling product was an Al based nanostructure. This product can be transformed into an AlN‐Al nanocomposite upon heating below the melting point of Al. It was found that the level of unreacted Al is dependent on milling time. The maximum amount of AlN was 88.28 wt %. The structure of as‐milled and annealed samples was investigated using x‐ray diffractometry and transmission electron microscopy. Differential thermal analysis was performed on as‐milled …