| MIMO Underwater Acoustic Communications for Rate Enhancement and Range Extension |
Dec 2009 |
16 pages |
| Authors:
Liuqing Yang; Jian Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
 | Our research focuses on the horizontal underwater acoustic communications. Towards the high rate objective, we address two key issues, namely channel estimation and symbol detection. To enhance channel estimation, we propose a cyclic approach (CA) for designing training sequences and an iterative adaptive approach (IAA) for estimating the channel. We also present a minimum mean-squared error (MMSE) based symbol detector, RELAX-BLAST, which combines vertical Bell Labs Layered Space-Time (V-BLAST) algorithm ... |
|
| Multi-Input Multi-Output (MIMO) Radar - Diversity Means Superiority |
Oct-2009 |
7 pages |
| Authors:
Jian Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| A multiple-input multiple-output (MIMO) radar system, unlike a standard phased-array radar, can transmit via its antennas linearly independent waveforms. We have made significant contributions on exploiting the waveform diversity offered by MIMO radar to achieve superior performance. First, we have considered a MIMO radar system where both the transmitter and receiver have multiple well-separated subarrays with each subarray containing closely-spaced antennas. Because of this general antenna configuration, both the waveform ... |
|
| MIMO-UAC for Rate Enhancement and Range Extension |
Dec-2008 |
14 pages |
| Authors:
Jian Li; Liuqing Yang; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| Our research focuses on the horizontal underwater acoustic communications. During this year, our research on multi-input multi-output underwater acoustic communications (MIMO-UAC) can be categorized into two thrusts: (1) Robust MIMO-UAC with Low-Complexity Receivers and (2) Enhanced Channel Estimation and Symbol Detection for High Speed MIMO-UAC. In terms of MIMO-UAC with low-complexity receivers, we have established a simple windowed least squares (LS) channel estimator, developed a differential MIMO scheme obviating channel ... |
|
| Multi-Input Multi-Output (MIMO) Radar - Diversity Means Superiority |
15-Oct-2008 |
6 pages |
| Authors:
Jian Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| A multiple-input multiple-output (MIMO) radar uses multiple antennas to simultaneously transmit several linearly independent waveforms. It also uses multiple antennas to receive the reflected signals. It has been shown that by exploiting this waveform diversity, MIMO radar can overcome performance degradations caused by radar cross section (RCS) fluctuations, achieve flexible spatial transmit beampattern designs, provide high-resolution spatial spectral estimates, and significantly improve the parameter identifiability. The MIMO radar can be ... |
|
| Contrast Enhancement for Thermal Acoustic Breast Cancer Imaging via Resonant Stimulation |
01-Mar-2008 |
30 pages |
| Authors:
Jian Li; Mark Sheplak; Lou Cattafesta; Henry Zmuda; Huabei Jiang; Manuel Arreola; FLORIDA UNIV GAINESVILLE
|
| This research plans to develop enhanced contrast thermal acoustic imaging (TAI) technology for the detection of breast cancer by combining amplitude-modulated (AM) electromagnetic (EM) field excitation resonant acoustic scattering and advanced signal processing techniques. While EM-induced TAI possesses great promise, the thermal acoustic signals tend to be weak However when the tumor is excited into resonance via EM stimulation the effective acoustic scattering cross-section may increase by a factor in ... |
|
| MIMO Underwater Acoustic Communications for Rate Enhancement and Range Extension |
10 DEC 2007 |
12 pages |
| Authors:
Liuqing Yang; Jian Li; FLORIDA UNIV GAINESVILLE ENGINEERING RESEARCH OFFICE
|
| Our research focuses on the horizontal underwater acoustic communications. For high data rate applications, such as image transmission or multiuser networks at long ranges. coherent underwater acoustic communication is of great importance. In this direction, we consider multi-input multi-output (MIMO) transmit beamforming under the uniform elemental power constraint. This is a non-convex optimization problem, and the optimal transmit beamformer is usually difficult to construct. We will first find a beamforming ... |
|
| MIMO Radar - Diversity Means Superiority |
OCT 2007 |
41 pages |
| Authors:
Jian Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| We consider a multiple-input multiple-output (MIMO) radar system where both the transmitter and receiver have multiple well-separated subarrays with each subarray containing closely-spaced antennas. Because of this general antenna configuration, both the coherent processing gain and the spatial diversity gain can be simultaneously achieved. We compare several spatial spectral estimators, including Capon and APES, for target detection and parameter estimation. We introduce a generalized likelihood ratio test (GLRT) and a ... |
|
| Contrast Enhancement for Thermal Acoustic Breast Cancer Imaging via Resonant Stimulation |
MAR 2007 |
40 pages |
| Authors:
Jian Li; Mark Sheplak; Lou Cattafesta; Henry Zmuda; Huabei Jiang; Manuel Arreola; FLORIDA UNIV GAINESVILLE
|
| This research plans to develop enhanced contrast thermal acoustic imaging (TAI) technology for the detection of breast cancer by combining amplitude-modulated (AM) electromagnetic (EM) field excitation resonant acoustic scattering and advanced signal processing techniques. While EM-induced TAI possesses great promise the thermal acoustic signals tend to be weak. However when the tumor is excited into resonance via EM stimulation the effective acoustic scattering cross-section may increase by a factor in ... |
|
| Online Job Assistance for Procedural Tasks in Mission Operations |
2005 |
7 pages |
| Authors:
John L. Mohammed; James C. Ong; Jian Li; H. B. Sorensen; STOTTLER HENKE ASSOCIATES INC SAN MATEO CA
|
| Military and commercial sectors are increasing their use of low earth orbit satellite constellations. However, low orbit constellations significantly increase the burden for ground-based system management because more satellites must be managed, and each satellite is in view for only brief periods of time. Therefore, ground station and satellite operators must be well-trained and supported by job-aids to exploit every contact opportunity. Stottler Henke is addressing this need through development ... |
|
| Rapid Authoring of Task Knowledge for Training and Performance Support |
2005 |
13 pages |
| Authors:
John L. Mohammed; Barbara Sorensen; James C. Ong; Jian Li; STOTTLER HENKE ASSOCIATES INC SAN MATEO CA
|
| This paper describes an intelligent job aid and integrated simulation-based tutoring system developed for the Air Force to help satellite operators carry out complex command plans. These systems use hierarchical, object-oriented task representations that enable rapid authoring by non-programmers while supporting sophisticated job aiding and student performance evaluation. For example, the tutoring scenario editor enables the instructor to create an initial solution template by demonstrating a correct sequence of actions. ... |
|
| Rapid Development of Scenario-Based Simulations and Tutoring Systems |
2005 |
8 pages |
| Authors:
John L. Mohammed; Barbara Sorensen; James C. Ong; Jian Li; STOTTLER HENKE ASSOCIATES INC SAN MATEO CA
|
| Low earth orbit constellations significantly increase the burden for ground-based systems management. Efficient, accurate management requires that ground station and satellite operators are well-trained. Scenario-based training, in which trainees practice handling specific situations using faithful simulations of the equipment they will use on the job has proven to be an extremely effective method for both training and certification. Effectiveness is increased when it is coupled with intelligent tutoring. Intelligent tutoring ... |
|
| Acoustic Proximity Ranging in the Presence of Secondary Echoes |
OCT 2003 |
14 pages |
| Authors:
Xi Li; Renbiao Wu; Srihari Rasmi; Jian Li; III Cattafesta Louis N.; Mark Sheplak; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| Proximity ranging is very important in many applications. Ultrasonic sensors have proven to be very cost effective tools for this purpose. Most of the currently available time-of-flight based acoustic proximity ranging systems use the conventional matched filter based time delay estimation approaches to measure short distances between proximity objects. However, in the presence of strong and closely spaced secondary echoes, the aforementioned matched filter based algorithms tend to fail or ... |
|
| Parametric Study of NCl(alpha sup 1 delta), NCl(beta sup 1 Sigma) from the Reaction of Cl/Cl2/He + HN3/He |
17 JUL 2002 |
8 pages |
| Authors:
Liping Duo; Shukai Tang; Jian Li; Xiangde Min; Fengting Sang; ACADEMIA SINICA DALIAN (CHINA) DALIAN INST OF CHEMICAL PHYSICS
|
| By means of Microwave generator chlorine diluted by helium is dissociated to chlorine atoms that subsequently react with hydrogen azide to produce excited states of NCl(alpha sup 1 delta) and NCl(beta sup 1 Sigma). In this paper, the intensity of NCl(alpha sup 1 delta) and NCl(beta sup 1 Sigma) emission dependent on the flow rates of different gases is studied. Moreover, the production of NCl(alpha sup 1 delta) and NCl(beta ... |
|
| Phase-Shift-Based Time-Delay Estimators for Proximity Acoustic Sensors |
JAN 2002 |
11 pages |
| Authors:
Xi Li; Erik G. Larsson; Mark Sheplak; Jian Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| Time-delay estimation is important in a wide range of applications in oceanic engineering. In this paper, we present a novel time-delay estimation algorithm based on maximum likelihood theory for the case that the measurements are corrupted by colored or nonuniform zero-mean Gaussian noise. It turns out that the likelihood function associated with the problem is highly oscillatory, and we propose a computationally efficient technique to maximize this function. Our algorithm ... |
|
| Study of Abrasive Wear Resistance of Transformation Toughened Ceramics. |
1993 |
|
| Authors:
Dongfang Wang; Jian Li; Zhiyuan Mao; ZHEJIANG UNIV HANGZHOU (CHINA) DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
 | The decreasing abrasive wear rate of tetragonal zirconia polycrystal ceramic (TZP) with increasing load under experimental conditions is believed to be caused by the martensitic transformation of t-ZrO2 to m-ZrO2 in the abraded surface. The transformation toughened ceramics (TZP) appeared to give the best abrasive wear resistance among the ceramic studied in this experimental work. The surface failure of these ceramics was mainly due to the microfractural dropping and powder-type ... |
|
| Effect of Fiber Tow Size on the Thread Strength of Three-Dimensionally Braided Carbon/Epoxy Composites. |
1993 |
|
| Authors:
Pusheng Chen; Jian Li; Guoen Sun; Aly ElShiekh; NORTH CAROLINA STATE UNIV AT RALEIGH COLL OF TEXTILES
|
| This study shows the effect of fiber tow size, preform structure and resin type on the pull-out load of threaded composite holes. Two types of preforms, one with axials and the other without axials, were fabricated from 3K, 6K, and 12K carbon fiber tows. These preforms were consolidated with Epon828/T401 and TACTIX123/Melamine5260 respectively. Threaded holes were made in the specimens and the pull-out loads were tested. Test results were compared ... |
|
Reports by Author
