| 1. |
- Berndtsson, Mikael
(författare)
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Analyzing Course Configurations for Teaching Object-Oriented Modeling and Design
- 2005
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Ingår i: IEEE Transactions on Education. - : IEEE. - 0018-9359 .- 1557-9638. ; 48:2, s. 337-339
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents and analyzes an object-oriented analysis and design course that has been given in three different configurations for students who are already familiar with object-oriented programming. The results show that the course configurations have not had a major impact on the students' performances.
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| 2. |
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| 3. |
- Milano, F., et al.
(författare)
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An Open Source Power System Virtual Laboratory : The PSAT Case and Experience
- 2008
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Ingår i: IEEE Transactions on Education. - : IEEE. - 0018-9359 .- 1557-9638. ; 51:1, s. 17-23
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the authors’ experience in the assessment of laboratory activities based on an open source software package for power system analysis, namely, Power System Analysis Toolbox (PSAT). PSAT is currently used in several universities for both undergraduate and graduate courses. PSAT has also its own Web forum, which provides support to students and researchers all around the world, thus resulting in an almost unique example of ldquovirtual laboratoryrdquo over the Internet. This paper attempts to answer through a variety of real-life examples the following open questions: What are the practical and pedagogical advantages of using an open source software with respect to proprietary software for power system analysis? What happens if a power system virtual laboratory is freely available on the Web? What is the difference between a class-based and a Web-based virtual laboratory?
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| 4. |
- Ben Slimane, Slimane
(författare)
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Reducing the Peak-to-Average Power Ratio of OFDM Signals Through Precoding
- 2007
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Ingår i: IEEE Transactions on Vehicular Technology. - : IEEE. - 0018-9545 .- 1939-9359. ; 56:2, s. 686-695
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Tidskriftsartikel (refereegranskat)abstract
- Orthogonal-frequency-division-multiplexing (OFDM) techniques allow the transmission of high data rates over broadband radio channels subject to multipath fading without the need for powerful channel equalization. However, they are very sensitive to nonlinear effects due to the high peak-to-average power ratio (PAPR) owned by their transmitted signals. This paper proposes an efficient technique for reducing the PAPR of OFDM signals. The proposed technique is data-independent and, thus, does not require new processing and optimization for each transmitted OFDM block. The reduction in PAPR of the OFDM signal is obtained through a proper selection of a precoding scheme that distributes the power of each modulated symbol over the OFDM block. The obtained results show that this precoding scheme is an attractive solution to the PAPR problem of OFDM signals. It is shown, through computer simulations, that the PAPR of precoded OFDM signals approaches that of single-carrier signals. The good improvement in PAPR given by the present technique permits the reduction of the complexity and cost of the transmitter significantly. The precoding schemes also take advantage of the frequency variations of the communication channel and can provide considerable performance gain in fading-multipath channels.
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| 5. |
- Devarakota, Pandu Ranga Rao, et al.
(författare)
-
3-D-Skeleton-Based Head Detection and Tracking Using Range Images
- 2009
-
Ingår i: IEEE Transactions on Vehicular Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9545 .- 1939-9359. ; 58:8, s. 4064-4077
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Tidskriftsartikel (refereegranskat)abstract
- Vision-based 3-D head detection and tracking systems have been studied in several applications like video surveillance, face-detection systems, and occupant posture analysis. In this paper, we present the development of a topology-based framework using a 3-D skeletal model for the robust detection and tracking of a vehicle occupant's head position from low-resolution range image data for a passive safety system. Unlike previous approaches to head detection, the proposed approach explores the topology information of a scene to detect the position of the head. Among the different available topology representations, the Reeb graph technique is chosen and is adapted to low-resolution 3-D range images. Invariance of the graph under rotations is achieved by using a Morse radial distance function. To cope with the particular challenges such as the noise and the large variations in the density of the data, a voxel neighborhood connectivity notion is proposed. A multiple-hypothesis tracker (MHT) with nearest-neighbor data association and Kalman filter prediction is applied on the endpoints of the Reeb graph to select and filter the correct head candidate out of Reeb graph endpoints. A systematic evaluation of the head detection framework is carried out on full-scale experimental 3-D range images and compared with the ground truth. It is shown that the Reeb graph topology algorithm developed herein allows the correct detection of the head of the occupant with only two head candidates as input to the MHT. Results of the experiments demonstrate that the proposed framework is robust under the large variations of the scene. The processing requirements of the proposed approach are discussed. It is shown that the number of operations is rather low and that real-time processing requirements can be met with the proposed method.
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| 6. |
- Devarakota, Pandu Ranga Rao, et al.
(författare)
-
Occupant classification using range images
- 2007
-
Ingår i: IEEE Transactions on Vehicular Technology. - : IEEE. - 0018-9545 .- 1939-9359. ; 56:4, s. 1983-1993
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Tidskriftsartikel (refereegranskat)abstract
- Static occupant classification is an important requirement in designing so-called smart airbags. Systems for this purpose can be either based on pressure sensors or vision sensors. Vision-based systems are advantageous over pressure-sensor-based systems as they can provide additional functionalities like dynamic occupant-position analysis or child-seat orientation detection. The focus of this paper is to evaluate and analyze static occupant classification using a low-resolution range sensor, which is based on the time-of-flight principle. This range sensor is advantageous, since it provides directly a dense range image that is independent of the ambient illumination conditions and object textures. Herein, the realization of an occupant-classification system, using a novel low-resolution range image sensor, is described, methods for extracting robust features from the range images are investigated, and different classification methods are evaluated for classifying occupants. Bayes quadratic classifier, Gaussian mixture-model classifier, and polynomial classifier are compared to a clustering-based linear-regression classifier using a polynomial kernel. The latter one shows improved results compared to the first-three classification methods. Full-scale tests have been conducted on a wide range of realistic situations with different adults and child seats in various postures and positions. The results prove the feasibility of low-resolution range images for the current application.
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| 7. |
- Fröberg, Anders, et al.
(författare)
-
Efficient Drive Cycle Simulation
- 2008
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 57:3, s. 1442-1453
-
Tidskriftsartikel (refereegranskat)abstract
- Drive cycle simulations of longitudinal vehicle models are important aids for the design and analysis of power trains, and tools currently on the market mainly use two different methods for such simulations: the forward dynamic and quasi-static inverse simulations. Here, a known theory for the stable inversion of nonlinear systems is used to combine the fast simulation times of the quasi-static inverse simulation with the ability of the forward dynamic simulation to include transient dynamics. The stable inversion technique and a new implicit driver model together form a new concept: inverse dynamic simulation. This technique is demonstrated to be feasible for vehicle propulsion simulation and specifically for three power train applications that include important dynamics that cannot be handled using quasi-static inverse simulation. The extensions are engine dynamics, driveline dynamics, and gas flow dynamics for diesel engines, which are also selected to represent important properties, such as zero dynamics, resonances, and nonminimum-phase systems. It is shown that inverse dynamic simulation is easy to set up, gives short simulation times, and gives consistent results for design space exploration. This makes inverse dynamic simulation a suitable method to use for drive cycle simulation, particularly in situations requiring many simulations, such as optimization over design space, power train configuration optimization, or the development of power train control strategies.
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| 8. |
- Geijer Lundin, Erik, et al.
(författare)
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Uplink Load in CDMA Cellular Radio Systems
- 2006
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Ingår i: IEEE Transactions on Vehicular Technology. - : IEEE Vehicular Technology Society. - 0018-9545 .- 1939-9359. ; 55:4, s. 1331-1346
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Tidskriftsartikel (refereegranskat)abstract
- Well-operating resource-management algorithms are crucial in wireless networks for ensuring the quality of service and, perhaps more importantly, for securing stability when operating at high load. These algorithms benefit from accurate feedback of the current network load. In the uplink of a code-division-multiple-access cellular network, the load is strongly related to the uplink noise rise, i.e., the ratio between total received power and background-noise power. This paper is primarily concerned with characterizing and approximating the uplink load. Two different load definitions are made. These relate to the received and transmitted carrier powers, respectively. Bounds that can be established in practice, e.g., before a resource decision is made, are used to develop a procedure for approximating the uplink load in practice. Furthermore, a stochastic approach to link budgets is used to establish the uplink load's role in the tradeoff between coverage and individual user satisfaction. Simulations indicate that the average error of the proposed load approximations is small for all load levels expected to appear in practice.
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| 9. |
- Hong, Yi, et al.
(författare)
-
Iterative switched decoding for interleave-division multiple-access systems
- 2008
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 57:3, s. 1939-1944
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we consider an interleave-division multiple-access (IDMA) system with multiple users transmitting over a shared additive white Gaussian noise channel. In an IDMA system, the information sequence of each user is encoded by a low-rate serially concatenated code consisting of a convolutional code and a repetition code. To reduce decoding complexity, it has been proposed to only decode the inner repetition code for the first few iterations before including the full concatenated code constraints into the decoding process. Here, we characterize this concept of switched decoding as the parallel decoding of two complementary punctured codes and propose a systematic design procedure based on the extrinsic information transfer chart and trajectory analyses, leading to the best decoding convergence-complexity tradeoffs.
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| 10. |
- Huang, Jinliang, et al.
(författare)
-
On Performance of Adaptive Modulation in MIMO Systems Using Orthogonal Space-Time Block Codes
- 2009
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 58:8, s. 4238-4247
-
Tidskriftsartikel (refereegranskat)abstract
- We provide a systematic study of adaptive modulation schemes in multiple-input multiple-output (MIMO)orthogonal space-time block codes (OSTBC) systems. Closed-form expressions are obtained to evaluate systemperformance, e.g., average spectral efficiency, bit-error-ratio (BER), and outage probability. Provided the closedformexpressions, the optimal SNR thresholds that yield the maximal average spectral efficiency can be solved. Inorder to reduce complexity of the optimal algorithm, an original method which can achieve approximately the sameperformance as the optimal one is proposed. Furthermore, we apply these methods in a more practical situation,where channel estimation is imperfect, and examine how the performance is affected due to channel estimationerrors.
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