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Articles 1 - 13 of 13
Full-Text Articles in Physical Sciences and Mathematics
Analyzing The Kinetics Of A Bromophenol Blue Fading Reaction In Basic Conditions For An Undergraduate Lab, Zeljka Popovic
Analyzing The Kinetics Of A Bromophenol Blue Fading Reaction In Basic Conditions For An Undergraduate Lab, Zeljka Popovic
Georgia College Student Research Events
Bromophenol blue is a common pH indicator and dye used in many different industries. Once a solution of bromophenol blue is placed in a concentrated basic solution, the color fades from a blue/violet color to clear solution with a pH of 4.6 or greater. The rate law of the reaction is analyzed through the use of a small footprint visible-near-infrared spectrometer (Vis-NIR) with a diode array detector. An absorbance wavelength of 590 nm as a function of time was collected using Ocean Optics OceanView software. The results contained in the data collection file are exported to a spreadsheet for further …
A Generalized Algorithm For The Generation Of Correlated Rayleigh Fading Envelopes In Wireless Channels, Le Chung Tran, Tadeusz Wysocki, Alfred Mertins, Jennifer Seberry
A Generalized Algorithm For The Generation Of Correlated Rayleigh Fading Envelopes In Wireless Channels, Le Chung Tran, Tadeusz Wysocki, Alfred Mertins, Jennifer Seberry
Dr Le Chung Tran
Although generation of correlated Rayleigh fading envelopes has been intensively considered in the literature, all conventional methods have their own shortcomings, which seriously impede their applicability. In this paper, a very general, straightforward algorithm for the generation of an arbitrary number of Rayleigh envelopes with any desired, equal or unequal power, in wireless channels either with or without Doppler frequency shifts, is proposed. The proposed algorithm can be applied to the case of spatial correlation, such as with multiple antennas in Multiple Input Multiple Output (MIMO) systems, or spectral correlation between the random processes like in Orthogonal Frequency Division …
Stc-Mimo Block Spread Ofdm In Frequency Selective Rayleigh Fading Channels, Le Chung Tran, Xiaojing Huang, Eryk Dutkiewicz, Joe F. Chicharo
Stc-Mimo Block Spread Ofdm In Frequency Selective Rayleigh Fading Channels, Le Chung Tran, Xiaojing Huang, Eryk Dutkiewicz, Joe F. Chicharo
Dr Le Chung Tran
In this paper, we expand the idea of spreading the transmitted symbols in OFDM systems by unitary spreading matrices based on the rotated Hadamard or rotated Discrete Fourier Transform (DFT) matrices proposed in the literature to apply to Space-Time Coded Multiple-Input Multiple-Output OFDM (STC-MIMO-OFDM) systems. We refer the resulting systems to as STC-MIMO Block Spread OFDM (STC-MIMO-BOFDM) systems. In the proposed systems, a multi-dimensional diversity, including time, frequency, space and modulation diversities, can be used, resulting in better bit error performance in frequency selective Rayleigh fading channels compared to the conventional OFDM systems with or without STCs. Simulations carried out …
Luminescence Dating Of Chinese Loess Beyond 130 Ka Using The Non-Fading Signal From K-Feldspar, Bo Li, Shenghua Li
Luminescence Dating Of Chinese Loess Beyond 130 Ka Using The Non-Fading Signal From K-Feldspar, Bo Li, Shenghua Li
Faculty of Science - Papers (Archive)
A multi-elevated-temperature post-IR IRSL (MET-pIRIR) protocol, which utilizes the IRSL signals measured by progressively increasing the stimulation temperature from 50 to 300 ℃ in a step of 50 ℃, was applied to date the potassium-rich feldspar (K-feldspar) extracts from loess samples at the Luochuan section of the Chinese Loess Plateau. It was observed that the MET-pIRIR ages obtained at elevatedtemperatures (250 and 300 ℃) are consistent with independent chronological control for the samples from the first loess layer (L1) to the third paleosol layer (S3), which correspond to the marine isotope stages (MIS) 2e9. Our results indicate that the MET-pIRIR …
A Reply To The Comments By Thomsen Et Al. On "Luminescence Dating Of K-Feldspar From Sediments: A Protocol Without Anomalous Fading Correction", Bo Li, Shenghua Li
A Reply To The Comments By Thomsen Et Al. On "Luminescence Dating Of K-Feldspar From Sediments: A Protocol Without Anomalous Fading Correction", Bo Li, Shenghua Li
Faculty of Science - Papers (Archive)
We are pleased that Thomsen et al. (2012) has tested our newly proposed multi-elevated-temperature post-IR IRSL (MET-pIRIR) procedure (Li and Li, 2011) using their own samples, which provides an independent test on the validity of this procedure. In their study, Thomsen et al. (2012) found that the METpIRIR procedure gave consistent results with the two-step post-IR IRSL (TS-pIRIR) procedure originally proposed by [Thomsen et al., 2008] and [Buylaert et al., 2009] and Thiel et al. (2010), indicating the validity of both methods for their samples investigated. Based on this observation, they argued that the MET-pIRIR procedure has no advantage over …
A Significant Component Of Ageing (Dna Damage) Is Reflected In Fading Breeding Colors: An Experimental Test Using Innate Antioxidant Mimetics In Painted Dragon Lizards, Mats Olsson, Michael Tobler, Mo Healey, Cecile Perrin, Mark Wilson
A Significant Component Of Ageing (Dna Damage) Is Reflected In Fading Breeding Colors: An Experimental Test Using Innate Antioxidant Mimetics In Painted Dragon Lizards, Mats Olsson, Michael Tobler, Mo Healey, Cecile Perrin, Mark Wilson
Mark R Wilson
A decade ahead of their time, von Schantz et al. united sexual selection and free radical biology by identifying causal links between deep-rooted physiological processes that dictate resistance to toxic waste from oxidative metabolism (reactive oxygen species, ROS), and phenotypic traits, such as ornaments.Ten years later, these ideas have still only been tested with indirect estimates of free radical levels (oxidative stress) subsequent to the action of innate and dietary antioxidants. Here, we measure net superoxide (a selection pressure for antioxidant production) and experimentally manipulate superoxide antioxidation using a synthetic mimetic of superoxide dismutase (SOD), Eukarion 134 (EUK). We then …
Reverberation-Chamber Test Environment For Outdoor Urban Wireless Propagation Studies, Helge Fielitz, Kate A. Remley, Christopher L. Holloway, Qian Zhang, Qiong Wu, David W. Matolak
Reverberation-Chamber Test Environment For Outdoor Urban Wireless Propagation Studies, Helge Fielitz, Kate A. Remley, Christopher L. Holloway, Qian Zhang, Qiong Wu, David W. Matolak
Faculty Publications
We introduce a test environment to replicate the well-known clustering of reflections in power delay profiles arising from late-time delays and reflections. Urban wireless propagation environments are known to exhibit such clustering. The test setup combines discrete reflections generated by a fading simulator with the continuous distribution of reflections created in a reverberation chamber. We describe measurements made in an urban environment in Denver, CO, that illustrate these multiple distributions of reflections. Our comparison of measurements made in the urban environment to those made in the new test environment shows good agreement.
Probability Density Functions For Snir In Ds-Cdma, David W. Matolak
Probability Density Functions For Snir In Ds-Cdma, David W. Matolak
Faculty Publications
Analytical expressions for the probability density function of block-wise signal-to-noise-plus-interference ratio for both synchronous and asynchronous direct-sequence spread spectrum code-division multiple access systems are developed, for equal average energy signals on the Gaussian and Rayleigh flat fading channels. Using the standard Gaussian approximation for multi-user interference, accurate density approximations are obtained, which agree very well with computer simulation results.
Scarcely Populated Uwb-Ir Systems With Interleaved Coding-Modulation On Multipath Fading Channels, Michal M. Pietrzyk, Keni Popovski, Tadeusz A. Wysocki, Beata J. Wysocki, Jos H. Weber
Scarcely Populated Uwb-Ir Systems With Interleaved Coding-Modulation On Multipath Fading Channels, Michal M. Pietrzyk, Keni Popovski, Tadeusz A. Wysocki, Beata J. Wysocki, Jos H. Weber
Faculty of Informatics - Papers (Archive)
Interleaved coding-modulation (ICM) is a recently proposed method for ultra-wideband impulse radio (UWB-IR) systems. ICM exploits the concept of chip interleaving, allowing to alleviate the problem of inter-symbol and inter-pulse interference commonly present in high data rate UWB-IR systems. In this paper, previous work on ICM is extended to scarcely populated multi-user scenarios. A novel design of a deterministic chip interleaver based on time-hopping hyperbolic congruence sequences is proposed. Furthermore, the main parameters of the random and hyperbolic interleavers are reviewed. The obtained results indicate that the proposed type of interleaver yields similar performance to random interleavers but with the …
Stc-Mimo Block Spread Ofdm In Frequency Selective Rayleigh Fading Channels, Le Chung Tran, Xiaojing Huang, Eryk Dutkiewicz, Joe F. Chicharo
Stc-Mimo Block Spread Ofdm In Frequency Selective Rayleigh Fading Channels, Le Chung Tran, Xiaojing Huang, Eryk Dutkiewicz, Joe F. Chicharo
Faculty of Informatics - Papers (Archive)
In this paper, we expand the idea of spreading the transmitted symbols in OFDM systems by unitary spreading matrices based on the rotated Hadamard or rotated Discrete Fourier Transform (DFT) matrices proposed in the literature to apply to Space-Time Coded Multiple-Input Multiple-Output OFDM (STC-MIMO-OFDM) systems. We refer the resulting systems to as STC-MIMO Block Spread OFDM (STC-MIMO-BOFDM) systems. In the proposed systems, a multi-dimensional diversity, including time, frequency, space and modulation diversities, can be used, resulting in better bit error performance in frequency selective Rayleigh fading channels compared to the conventional OFDM systems with or without STCs. Simulations carried out …
An Adaptive Scalable Multiuser-Ofdm System For Multimedia Transmission Over Fading Channels, Ahmed Muthana M. Nadhim, Jianhua He, Jiangtao Xi, Zongkai Yang
An Adaptive Scalable Multiuser-Ofdm System For Multimedia Transmission Over Fading Channels, Ahmed Muthana M. Nadhim, Jianhua He, Jiangtao Xi, Zongkai Yang
Faculty of Informatics - Papers (Archive)
In this paper, an adaptive scalable multiuser-OFDM system was proposed for multimedia transmission over fading channels. The proposed adaptive algorithm can adapt according to the channel status information of each user's channel status. This algorithm dynamically changes according to the user's channel changes; this can keep fixed QoS at the physical layer. Another predefined QoS for different sessions and services to be provided for different users. This QoS can be guaranteed by multimedia scalability. Scalability can adapt to the service requirements, in terms of transmission data rate and bandwidth. As a result, a robust multimedia transmission scheme is achieved by …
A Generalized Algorithm For The Generation Of Correlated Rayleigh Fading Envelopes In Wireless Channels, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins, Jennifer R. Seberry
A Generalized Algorithm For The Generation Of Correlated Rayleigh Fading Envelopes In Wireless Channels, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins, Jennifer R. Seberry
Faculty of Informatics - Papers (Archive)
Although generation of correlated Rayleigh fading envelopes has been intensively considered in the literature, all conventional methods have their own shortcomings, which seriously impede their applicability. In this paper, a very general, straightforward algorithm for the generation of an arbitrary number of Rayleigh envelopes with any desired, equal or unequal power, in wireless channels either with or without Doppler frequency shifts, is proposed. The proposed algorithm can be applied to the case of spatial correlation, such as with multiple antennas in Multiple Input Multiple Output (MIMO) systems, or spectral correlation between the random processes like in Orthogonal Frequency Division …
Detection Of Co And Dust Emission In Near-Infrared Spectra Of Sn 1998s, Christopher L. Gerardy, Robert A. Fesen, Peter Höflich, J. Craig Wheeler
Detection Of Co And Dust Emission In Near-Infrared Spectra Of Sn 1998s, Christopher L. Gerardy, Robert A. Fesen, Peter Höflich, J. Craig Wheeler
Dartmouth Scholarship
Near-infrared spectra (0.95 – 2.4 μ m) of the peculiar Type IIn supernova 1998S in NGC 3877 from 95 to 355 days after maximum light are presented. K -band data taken at days 95 and 225 show the presence of the first overtone of CO emission near 2.3 μ m, which is gone by day 355. An apparent extended blue wing on the CO profile in the day 95 spectrum could indicate a large CO expansion velocity (≈ 2000 – 3000 km s − 1). This is the third detection of infrared CO emission in nearly as many Type II …