Capacity Analysis (capacity + analysis)

Distribution by Scientific Domains
Engineering80%

Selected Abstracts

Capacity analysis for underlaying CDMA microcell/macrocell systems

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2001
Jen-Kung Chung
Abstract The CDMA system can provide more capacity than the conventional AMPS system and the hierarchical layer of cells is required for system design in the future. However, the problem is whether the same RF channels used in a CDMA underlaying macrocell/microcell structure also obtain high capacity as in the homogeneous structure. This paper investigates the interference of uplink and downlink from both the microcell and macrocell in a hierarchical structure. Downlink power control is also considered. The results show that the capacity of microcell in a hierarchical structure is 23 per cent less than in homogeneous cells. The capacity of macrocell in a hierarchical structure decreases dramatically in proportion to the number of microcells. The capacities of the microcell and macrocell are limited in downlink, and uplink, respectively. In addition, more efforts for microcell should be made, such as more power is transmitted by microcell basestation if the same RF channel is used in a hierarchical structure. The results suggest that different RF channels are used in a two-tier cellular environment. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Performance-based seismic analysis and design of suspension bridges

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4-5 2005
Serafim Arzoumanidis
Abstract This paper presents a performance-based seismic analysis and design of a large suspension bridge, the new Tacoma Narrows Parallel Crossing in the State of Washington. The scope of the project included establishment of design criteria, extensive analysis and validation of the design. The analysis was performed using detailed three-dimensional models that included geometric and material non-linearity. The target post-earthquake level of service was verified using stress, deformation and ductility criteria. In the absence of well-established criteria, which relate the structural response of tower shafts to specific levels of performance, capacity analyses were performed to demonstrate that the design fulfills the performance objectives. The seismic analysis and design of this bridge was reviewed throughout the design process. An independent check team also performed separate analysis and validation of the design. Thus, this bridge constitutes an example of a large-scale design project where the performance-based seismic design procedures underwent rigorous assessment. This work demonstrated that the performance-based approach for seismic design is an appropriate way for designing earthquake-resistant structures. Further data that relate the structural response with the performance objectives are necessary. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Seismic reliability of V-braced frames: Influence of design methodologies

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2009
Alessandra Longo
Abstract According to the most modern trend, performance-based seismic design is aimed at the evaluation of the seismic structural reliability defined as the mean annual frequency (MAF) of exceeding a threshold level of damage, i.e. a limit state. The methodology for the evaluation of the MAF of exceeding a limit state is herein applied with reference to concentrically ,V'-braced steel frames designed according to different criteria. In particular, two design approaches are examined. The first approach corresponds to the provisions suggested by Eurocode 8 (prEN 1998,Eurocode 8: design of structures for earthquake resistance. Part 1: general rules, seismic actions and rules for buildings), while the second approach is based on a rigorous application of capacity design criteria aiming at the control of the failure mode (J. Earthquake Eng. 2008; 12:1246,1266; J. Earthquake Eng. 2008; 12:728,759). The aim of the presented work is to focus on the seismic reliability obtained through these design methodologies. The probabilistic performance evaluation is based on an appropriate combination of probabilistic seismic hazard analysis, probabilistic seismic demand analysis (PSDA) and probabilistic seismic capacity analysis. Regarding PSDA, nonlinear dynamic analyses have been carried out in order to obtain the parameters describing the probability distribution laws of demand, conditioned to given values of the earthquake intensity measure. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Erlang capacity analysis of hybrid FDMA/CDMA systems supporting multi-class services according to channel assignment methods

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2002
Insoo Koo
Abstract In this paper, we focus on the evaluation of the Erlang capacity for hybrid FDMA/CDMA systems supporting multi-class services with two channel allocation schemes: independent carrier channel assignment (ICCA) and combined carrier channel assignment (CCCA). For the performance analysis, a multi-dimensional Markov chain model is developed. The effect of the number of carriers of hybrid FDMA/CDMA system on the Erlang capacity is observed, and the optimum values of the system parameters such as the number of channel elements (CEs) and the number of carriers are selected with respect to the Erlang capacity. As a numerical example, we consider an FDMA/CDMA system supporting voice/data services. We find out that, even though the benefit of CCCA scheme over ICCA scheme is negligible for small number of CEs, the scenario changes significantly when the number of CEs increases beyond a certain point. An improvement of as much as 74% can be achieved in the Erlang capacity when 5 carriers are employed. We also find the capacity knees for different number of carriers. The results of this paper could be helpful in the traffic engineering of FDMA/CDMA systems providing multi-class services. Copyright © 2002 John Wiley & Sons, Ltd. [source]

CITGO Petroleum Meeting the Challenge with ABM

JOURNAL OF CORPORATE ACCOUNTING & FINANCE, Issue 3 2002
Marlene B. Rodriguez
Activity-based management (ABM) has helped process and energy industries cut costs and improve efficiencies, because it provides the baseline data needed for performance measurement, outsourcing, product costing, and capacity analysis. However, implementations of ABM have to be tailored to meet the unique challenges posed by Shared Services functions and operational units. This article outlines CITGO's implementation techniques for ABM and describes the company's results for its Shared Services and operations business units. © 2002 Wiley Periodicals, Inc. [source]