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Full-Text Articles in Social and Behavioral Sciences
A Best-First Anytime Algorithm For Computing Optimal Coalition Structures, Chattrakul Sombattheera, Aditya K. Ghose
A Best-First Anytime Algorithm For Computing Optimal Coalition Structures, Chattrakul Sombattheera, Aditya K. Ghose
Faculty of Engineering and Information Sciences - Papers: Part A
This work presents a best-first anytime algorithm for computing optimal coalition structures. The approach is novel in that it generates coalition structures based on coalition values, while existing algorithms base their generation on the structure (members and configurations) of coalitions. With our algorithm, coalition structures are generated by repeatedly choosing the best coalition, as determined using a novel metric called agent's contribution to coalition structure that we define. We have compared the performance of our algorithm against that of Rahwan et al [5] using 20 data distributions. Our results show that our algorithm almost always converges on an optimal coalition …
Fitting Position Latent Cluster Models For Social Networks With Latentnet, Pavel N. Krivitsky, M Handcock
Fitting Position Latent Cluster Models For Social Networks With Latentnet, Pavel N. Krivitsky, M Handcock
Faculty of Engineering and Information Sciences - Papers: Part A
latentnet is a package to fit and evaluate statistical latent position and cluster models for networks. Hoff, Raftery, and Handcock (2002) suggested an approach to modeling networks based on positing the existence of an latent space of characteristics of the actors. Relationships form as a function of distances between these characteristics as well as functions of observed dyadic level covariates. In latentnet social distances are represented in a Euclidean space. It also includes a variant of the extension of the latent position model to allow for clustering of the positions developed in Handcock, Raftery, and Tantrum (2007). The package implements …
High Spatial Resolution Fibre -Optic Fizeau Interferometric Strain Sensor Based On An In-Fiber Spherical Microcavity, Enbang Li, Gang-Ding Peng, Xin Ding
High Spatial Resolution Fibre -Optic Fizeau Interferometric Strain Sensor Based On An In-Fiber Spherical Microcavity, Enbang Li, Gang-Ding Peng, Xin Ding
Faculty of Engineering and Information Sciences - Papers: Part A
We present a fiber-optic Fizeau interferometric strain sensor consisting of an in-fiber spherical microcavity of 39um in diameter. The spherical microcavity was formed by splicing a normal single-mode fiber with a hollow-core photonic crystal fiber. We demonstrate that strain sensing can be realized by using the interference between the light signals reflected by the front and rear surfaces of the sphere. Experiments have shown that the strain sensor has a strain sensitivity of 3.36um/ue and a temperature sensitivity of 1.35um/°C.
Fabrication And Characterisation Of Periodically Poled Lithium Niobate Waveguide Using Femtosecond Laser Pulses, Shuanggen Zhang, Jianghong Yao, Qing Shi, Yange Liu, Weiwei Liu, Zhangchao Huang, Fuyun Lu, Enbang Li
Fabrication And Characterisation Of Periodically Poled Lithium Niobate Waveguide Using Femtosecond Laser Pulses, Shuanggen Zhang, Jianghong Yao, Qing Shi, Yange Liu, Weiwei Liu, Zhangchao Huang, Fuyun Lu, Enbang Li
Faculty of Engineering and Information Sciences - Papers: Part A
We present in this letter the fabrication and characterization of thermally stable type II waveguides in Z-cut periodically poled lithium niobate crystals. The waveguides were fabricated by using a femtosecond laser and were utilized for second harmonic generation. Our experiments have shown that a quasiphase matching wavelength of 1548.2nm, a tuning bandwidth of 2nm, and a tuning temperature range of 150.4±1.6°C can be achieved.
Hydraulic Fracturing In Underground Coal Mines, Dennis John Black, Naj Aziz
Hydraulic Fracturing In Underground Coal Mines, Dennis John Black, Naj Aziz
Faculty of Engineering and Information Sciences - Papers: Part A
The success of hydraulic fracturing application in stimulating gas drainage from coal seams is influenced by the ground stress conditions and the effective installation of straddled packers. A total of five holes were drilled in the Bulli Seam in a mine (Mine A) and tested for increased gas stimulation by hydraulic fracturing. Parameters examined included casing material integrity for cutability and ability to resist the external collapse during grouting and hydraulic fracturing. Changes made to the injecti on pressure, casing wall thickness, slot orientation (circumferential instead of axial) and controlled pressure release rate post-treatment improved the hydraulic fracturing treatment. However, …
Gas Drainage Improvement In Underground Coal Mines, Dennis John Black, Naj Aziz
Gas Drainage Improvement In Underground Coal Mines, Dennis John Black, Naj Aziz
Faculty of Engineering and Information Sciences - Papers: Part A
Effective gas management is vital to the success of the longwall mining in the Bulli seam, in the Southern Coalfield, Sydney Basin, NSW, Australia. The evolution of gas drainage methods and practices are discussed with respect to gas type, gas drainage lead time and prevailing geological conditions. Both underground to inseam drilling and surface to inseam drilling techniques are described at both pre and post-drainage conditions. Post-drainage of gas from longwall is discussed for its effectiveness, practicability and efficiency. The long term benefit of the method selected is examined with respect to gas capture efficiency. An alternative method of surface …
Improving Uis Gas Drainage In Underground Coal Mines, Dennis John Black, Naj Aziz
Improving Uis Gas Drainage In Underground Coal Mines, Dennis John Black, Naj Aziz
Faculty of Engineering and Information Sciences - Papers: Part A
Gas drainage is considered one of the most effective controls in preventing coal and gas outbursts. The advances in mining equipment technology over the last 20 years have led to a significant increase in coal mine production, resulting in increased coal mine gas emission during the coal extraction process. High gas emissions, if not effectively managed, may exceed the diluting capability of the mine's ventilation system, potentially exceeding the statutory limit, resulting in gas related production delays. The development of underground to inseam (UIS) gas drainage is discussed. The study is focused on a range of factors which impact gas …
Numerical Analysis Of Roll Deflection For Sendzimir Mill, H L. Yu, X H. Liu, G T. Lee, X W. Li, H D. Park
Numerical Analysis Of Roll Deflection For Sendzimir Mill, H L. Yu, X H. Liu, G T. Lee, X W. Li, H D. Park
Faculty of Engineering and Information Sciences - Papers: Part A
The present work introduces a new type of numerical analyzing method: the contact element method with two relative coordinates (CEM). The main characteristic of the procedure is elements meshing on the basis of the contact length between objects and that each element has two relative coordinates. The ordinary expression of this procedure is DX[CXY(i)]=D Y[CYX(i)]. Through this method, the CEM function of the 20-high Sendzimir mill and the deflection function expression of every roll are obtained. A computational software SM4SM for the Sendzimir mill has been developed, by which the deflection condition of rolls S, O, I, and A can …
A Novel Dynamic Absorber Using Enhanced Magnetorheological Elastomers For Powertrain Vibration Control, Nong Zhang, Nga Hoang, Haiping Du
A Novel Dynamic Absorber Using Enhanced Magnetorheological Elastomers For Powertrain Vibration Control, Nong Zhang, Nga Hoang, Haiping Du
Faculty of Engineering and Information Sciences - Papers: Part A
This paper presents a novel Adaptive Tuned Vibration Absorber (ATVA) using the enhanced magnetorheological elastomers (MREs) for powertrain vibration reduction. The MRE material used in this application includes micro-sized iron particles enhanced by adding nano-sized magnetic powders. With the enhancement, MRE's elastic modulus significantly increases due to the MR effect. In the new ATVA, the MRE plays a role as a torsional spring whose stiffness coefficient can be varied with an external magnetic field. Additionally, this ATVA could operate in shear-squeeze mode rather than shear mode. Thus, the frequency range is much wider than that of general MREs. Such property …
Cost-Based Bdi Plan Selection For Change Propagation, Khanh Hoa Dam, Michael Winikoff
Cost-Based Bdi Plan Selection For Change Propagation, Khanh Hoa Dam, Michael Winikoff
Faculty of Engineering and Information Sciences - Papers: Part A
Software maintenance is responsible for as much as two thirds of the cost of any software, and is consequently an important research area. In this paper we focus on the change propagation problem: given a primary change that is made in order to meet a new or changed requirement, what additional, secondary, changes are needed? We build on previous work that has proposed to use a BDI (belief-desire-intention) agent framework to propagate changes by fixing violations of consistency constraints. One question that needs to be answered as part of this framework is how to select between different applicable (repair) plan …
An Agent-Oriented Approach To Support Change Propagation In Software Evolution, Hoa K. Dam
An Agent-Oriented Approach To Support Change Propagation In Software Evolution, Hoa K. Dam
Faculty of Engineering and Information Sciences - Papers: Part A
Software maintenance and evolution is arguably a lengthy and expensive phase in the life cycle of a software system. A critical issue at this phase is change propagation: given a set of primary changes that have been made to software, what additional secondary changes are needed? Although many approaches have been proposed, automated change propagation is still a significant technical challenge in software maintenance and evolution. This paper presents a Ph.D. research in the final stages of developing and evaluating a novel, agent-based, framework to support semi-automated change propagation in evolving software systems.
Network Structure, Ict Use And Performance Attitudes Of Knowledge Workers, Kon Shing Kenneth Chung, Liaquat Hossain
Network Structure, Ict Use And Performance Attitudes Of Knowledge Workers, Kon Shing Kenneth Chung, Liaquat Hossain
Faculty of Engineering and Information Sciences - Papers: Part A
In this study, we examine the effect of social network structure and information and communication technologies (ICT) use on performance attitudes of knowledge-intensive workers in dispersed occupational communities. We first develop a theoretical framework and use it to develop a valid and reliable survey instrument. Secondly, we apply structural hole measures (constraint and efficiency) for exploring the association with ICT use and attitudes to performance. Empirical results suggest that density of knowledge workers' professional network is positively associated with ICT use whereas network efficiency is negatively correlated with ICT use at both task and communication-structure level. The findings show that …
Single- And Multi-Carrier Idma Schemes With Cyclic Prefixing And Zero Padding Techniques, Qinghua Guo, Xiaojun Yuan, Li Ping
Single- And Multi-Carrier Idma Schemes With Cyclic Prefixing And Zero Padding Techniques, Qinghua Guo, Xiaojun Yuan, Li Ping
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, we investigate single-carrier (SC) and multi-carrier IDMA schemes with cyclic prefixing (CP) and zero padding (ZP) techniques. These schemes are called SC-IDMA-CP, SC-IDMA-ZP, orthogonal frequency-division multiplexing (OFDM)-IDMA-CP and OFDM-IDMA-ZP, respectively. By exploiting the circulant property of channel matrices, the multi-user detection of these schemes can be efficiently realised with per-user complexity independent of the number of users and the length of inter-symbol interference (ISI) channels. We show the potential advantages of ZP-based schemes in power efficiency and convergence speed. Simulation results are provided to compare the four schemes. Copyright © 2008 John Wiley & Sons, Ltd.
Lmmse Turbo Equalization Based On Factor Graphs, Qinghua Guo, Li Ping
Lmmse Turbo Equalization Based On Factor Graphs, Qinghua Guo, Li Ping
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, a vector-form factor graph representation is derived for intersymbol interference (ISI) channels. The resultant graphs have a tree-structure that avoids the short cycle problem in existing graph approaches. Based on a joint Gaussian approximation, we establish a connection between the LLR (log-likelihood ratio) estimator for a linear system driven by binary inputs and the LMMSE (linear minimum mean-square error) estimator for a linear system driven by Gaussian inputs. This connection facilitates the application of the recently proposed Gaussian message passing technique to the cycle-free graphs for ISI channels. We also show the equivalence between the proposed approach …
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.
Impact Of Signaling Schemes On Iterative Linear Minimum-Mean-Square-Error Detection, Li Ping, Jun Tong, Xiaojun Yuan, Qinghua Guo
Impact Of Signaling Schemes On Iterative Linear Minimum-Mean-Square-Error Detection, Li Ping, Jun Tong, Xiaojun Yuan, Qinghua Guo
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, we study the iterative detection problem for a coded system with multi-ary modulation. We show that, with iterative linear minimum-mean-square-error (LMMSE) detection, superposition coded modulation (SCM) can provide performance superior to that with other traditional signaling schemes used in trellis coded modulation (TCM) and bit-interleaved coded modulation (BICM). This finding provides a useful guideline for system design considering inter-symbol interference (ISI) and other forms of interference. Simulation results are provided to illustrate the efficiency of the iterative LMMSE detection with different signaling schemes. © 2008 IEEE.
Joint Linear Interleaver Design For Concatenated Zigzag Codes, D S. Lin, S Tong, S Q. Li
Joint Linear Interleaver Design For Concatenated Zigzag Codes, D S. Lin, S Tong, S Q. Li
Faculty of Engineering and Information Sciences - Papers: Part A
The design of a class of well-structured low-density parity-check (LDPC) codes, namely linear interleaver based concatenated zigzag (LICZ) codes, is investigated. With summary distances as the design metric, short LICZ codes with large minimum distances can be constructed. Moreover, an efficient cycle-based method is proposed to compute the minimum distances of LICZ codes. Simulation results show that LICZ codes outperform both CZ codes with random interleavers and LDPC codes by the progressive edge growth algorithm.
Study Of The Energy Performance Of Korean Apartment Buildings With Alternative Balcony Configurations, Jo Clarke, Cameron Johnstone, Jaemin Kim, Georgios Kokogiannakis, Paul Strachan, Kyung-Hun Woo, Boo-Sik Kang
Study Of The Energy Performance Of Korean Apartment Buildings With Alternative Balcony Configurations, Jo Clarke, Cameron Johnstone, Jaemin Kim, Georgios Kokogiannakis, Paul Strachan, Kyung-Hun Woo, Boo-Sik Kang
Faculty of Engineering and Information Sciences - Papers: Part A
The purpose of this study is to evaluate the impact of the new regulations design changes on heating loads of apartment buildings and identify the construction configurations (e.g. glazing types, thermal properties, window area ratio, etc.) of the new designs that will ensure the energy performance is at least on the same level as those with a traditional balcony configuration.
Performance Analysis Of Multi-Ary Systems With Iterative Linear Minimum-Mean-Square-Error Detection, Li Ping, Jun Tong, Xiaojun Yuan, Qinghua Guo
Performance Analysis Of Multi-Ary Systems With Iterative Linear Minimum-Mean-Square-Error Detection, Li Ping, Jun Tong, Xiaojun Yuan, Qinghua Guo
Faculty of Engineering and Information Sciences - Papers: Part A
This paper is concerned with coded multi-ary systems over linear channels. Based on a semi-analytical evolution technique, the impact of signaling schemes on the performance of low-cost iterative linear minimum-mean-square-error (LMMSE) detection is studied. It is shown that superposition coded modulation (SCM) maximizes the output signal-to-noise ratio (SNR) of LMMSE detectors. Consequently, SCM may potentially outperform other conventional signaling schemes when LMMSE detectors are used. Numerical examples are provided to verify the theoretical analysis. © 2008 IEEE.
A Kernel-Induced Space Selection Approach To Model Selection Of Klda, Lei Wang, Kap Luk Chan, Ping Xue, Luping Zhou
A Kernel-Induced Space Selection Approach To Model Selection Of Klda, Lei Wang, Kap Luk Chan, Ping Xue, Luping Zhou
Faculty of Engineering and Information Sciences - Papers: Part A
Model selection in kernel linear discriminant analysis (KLDA) refers to the selection of appropriate parameters of a kernel function and the regularizer. By following the principle of maximum information preservation, this paper formulates the model selection problem as a problem of selecting an optimal kernel-induced space in which different classes are maximally separated from each other. A scatter-matrix-based criterion is developed to measure the "goodness" of a kernel-induced space, and the kernel parameters are tuned by maximizing this criterion. This criterion is computationally efficient and is differentiable with respect to the kernel parameters. Compared with the leave-one-out (LOO) or -fold …
Orbifolds Are Not Commutative Geometries, Adam C. Rennie, Joseph C. Varilly
Orbifolds Are Not Commutative Geometries, Adam C. Rennie, Joseph C. Varilly
Faculty of Engineering and Information Sciences - Papers: Part A
In this note we show that the crucial orientation condition for commutative geometries fails for the natural commutative spectral triple of an orbifold M/G.
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 …
Implementing Analytical Geometric And Penetration Response Correction For Keel-Edge Pinhole Spect Image Reconstruction, Xuezhu Zhang, Qiusheng Dai, Yujin Qi
Implementing Analytical Geometric And Penetration Response Correction For Keel-Edge Pinhole Spect Image Reconstruction, Xuezhu Zhang, Qiusheng Dai, Yujin Qi
Faculty of Engineering and Information Sciences - Papers: Part A
The collimator response compensation is very important in high-resolution pinhole SPECT imaging for resolution recovery and quantitative imaging. In this study the pinhole collimator response of the keel-edge aperture was investigated in terms of the geometric response function and penetration response function (GPRF). An approximate numerical method was proposed to implement the geometric and penetration response correction (GPRC) for keel-edge pinhole SPECT image reconstruction. A lookup table for the GPRC was calculated and then was utilized in the 3D pinhole iterative OSEM reconstruction procedure. The performance of the image reconstruction with the GPRC was evaluated using both the phantom and …
She-Pwm Switching Strategies For Active Neutral Point Clamped Multilevel Converters, Sridhar R. Pulikanti, Mohamed S. A Dahidah, Vassilios G. Agelidis
She-Pwm Switching Strategies For Active Neutral Point Clamped Multilevel Converters, Sridhar R. Pulikanti, Mohamed S. A Dahidah, Vassilios G. Agelidis
Faculty of Engineering and Information Sciences - Papers: Part A
The main drawback of the diode neutral-point-clamped (NPC) converter is the unequal loss distribution among the semiconductor devices which confines the maximum output power and the switching frequency. To address this drawback, switching state redundancy is required to evenly distribute the losses and can be achieved differently as the level of the converter changes. For instance, the three-level active NPC (3L-ANPC) converter has switching state redundancy and is derived from the 3L-NPC converter by adding an anti-parallel switch to the clamping diodes; in the 4L-ANPC converter, the combination of a 2L converter and a 3L-ANPC converter is used; in a …
Berkovich Indentation Of Diamondlike Carbon Coatings On Silicon Substrates, Ayesha J. Haq, Paul Munroe, Mark Hoffman, Phil Martin, Avi Bendavid
Berkovich Indentation Of Diamondlike Carbon Coatings On Silicon Substrates, Ayesha J. Haq, Paul Munroe, Mark Hoffman, Phil Martin, Avi Bendavid
Faculty of Engineering and Information Sciences - Papers: Part A
The deformation behavior of diamondlike carbon (DLC) coatings on silicon substrates induced by Berkovich indentation has been investigated. DLC coatings deposited by a plasma-assisted chemical vapor deposition technique were subjected to nanoindentation with a Berkovich indenter over a range of maximum loads from 100 to 300 mN. Distinct pop-ins were observed for loads greater than 150 mN. However, no pop-out was observed for the loads studied. The top surface of the indents showed annular cracks with associated fragmented material. The cross sections showed up to 20% localized reduction in thickness of the DLC coating beneath the indenter tip. Cracking, {111} …
The Evolution In Coal Mine Gas Extraction - A Response To Economic, Environmental And Community Pressures, Dennis John Black, Naj Aziz
The Evolution In Coal Mine Gas Extraction - A Response To Economic, Environmental And Community Pressures, Dennis John Black, Naj Aziz
Faculty of Engineering and Information Sciences - Papers: Part A
Effective gas management is vital to the success of the longwall mines operating in the Bulli seam, located in the Southern Sydney Basin, Australia. High gas emissions are characteristic of the region with specific gas emissions typically in the order of 30-45 m3/t. The mines that operate in this area have, since 1980, relied on the use of extensive underground to inseam (UIS) drilling to drain gas both ahead of advancing roadway development and following longwall coal extraction. With the ever increasing production capacity of modern mining machinery the UIS methods are struggling to drain sufficient gas from the coal …
Semifinite Spectral Triples Associated With Graph C*-Algebras, Alan L. Carey, John Phillips, Adam Rennie
Semifinite Spectral Triples Associated With Graph C*-Algebras, Alan L. Carey, John Phillips, Adam Rennie
Faculty of Engineering and Information Sciences - Papers: Part A
We review the recent construction of semifinite spectral triples for graph C^*-algebras. These examples have inspired many other developments and we review some of these such as the relation between the semifinite index and the Kasparov product, examples of noncommutative manifolds, and an index theorem in twisted cyclic theory using a KMS state.
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.
On Generalization Of Constitutive Models From Two Dimensions To Three Dimensions, N Khalili, M D. Liu
On Generalization Of Constitutive Models From Two Dimensions To Three Dimensions, N Khalili, M D. Liu
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, a study is made of the generalization of constitutive models for geomaterials from two-dimensional stress and strain states to three-dimensional stress and strain states. Existing methods of model generalization are reviewed and their deficiencies are highlighted. A new method is proposed based on geometries of the model imprints on two normal planes. Using the proposed method, various three dimensional failure criterions suitable for geomaterials are implemented directly into a two dimensional model and the generalized model is identical to its original form for the axially symmetric condition. To demonstrate the application of the proposed method, the Modified …
Performance Analysis Of Ofdm-Idma Systems With Peak-Power Limitation, Jun Tong, Qinghua Guo, Li Ping
Performance Analysis Of Ofdm-Idma Systems With Peak-Power Limitation, Jun Tong, Qinghua Guo, Li Ping
Faculty of Engineering and Information Sciences - Papers: Part A
This paper is concerned with orthogonal frequency-division multiplexing interleave-division multiple-access (OFDM-IDMA) systems over frequency-selective fading channels. Deliberate clipping is applied to reduce the peak-to-average power ratio (PAPR) of each user's transmitted signal. An iterative multiuser detection (MUD) technique is developed to recover the performance loss due to clipping. A semi-analytical signal-to- noise ratio (SNR) evolution technique is proposed, which can provide quick and accurate prediction of the iterative MUD performance. Numerical results show that the performance of OFDM-IDMA is not sensitive to the frequency selectivity of channels, and OFDM-IDMA is more power-efficient than other alternative multi-carrier transmission techniques. © 2008 …