427 results
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2. Comparative analysis of standardized indicators for Smart sustainable cities: What indicators and standards to use and when?
- Author
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Huovila, Aapo, Bosch, Peter, and Airaksinen, Miimu
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SMART cities , *COMPARATIVE studies , *NEEDS assessment , *CITY managers , *PERFORMANCE evaluation , *STANDARDS - Abstract
Abstract City managers need indicators for target setting, performance assessment, monitoring, management and decision-making purposes. The choice of the most suitable indicator framework is crucial, but difficult, as it requires expert knowledge. To help cities in their choice, this paper compares seven recently published indicator standards for Smart sustainable cities. A taxonomy was developed to evaluate each of their 413 indicators against five conceptual urban focuses (types of urban sustainability and smartness), ten sectoral application domains (energy, transport, ICT, economy, etc.) and five indicator types (input, process, output, outcome, impact). The results clearly discriminate between indicator standards suited for evaluating the implementation of predominantly smart city approaches versus standards more focused on sustainability assessment. A further distinction is possible in standards almost fully oriented towards impacts reached, and standards that allow for progress evaluation according to steps in the implementation process. Some standards provide a narrow focus on output indicators evaluating the progress in implementing smart urban ICT solutions (e.g. number of smart meters installed). Cities are encouraged to complement such evaluations with impact indicators that demonstrate the effects of those solutions. This paper provides guidance for city managers and policy makers to select the indicators and standard that best correspond to their assessment need and goals, and align with their stage in Smart sustainable city implementation. Graphical abstract Unlabelled Image Highlights • 7 city indicator standards (413 indicators) analyzed and compared • Clear differences in focus on sustainability or smartness and the role of ICT • Some standards focus on short-term evaluation of efficiency in smart city deployment. • Others allow evaluation of progress in steps, and achieved (sustainability) impacts. • Guidance for choice of an indicator standard that best suits your goal and need [ABSTRACT FROM AUTHOR]
- Published
- 2019
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3. Development of performance criteria for sustainability evaluation of modular versus conventional construction methods.
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Kamali, Mohammad and Hewage, Kasun
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CONSTRUCTION industry , *SUSTAINABILITY , *QUESTIONNAIRES , *PERFORMANCE evaluation , *COMPARATIVE studies - Abstract
Modular construction has been recognized as one of the primary methods for sustainable off-site construction in the recent past. However, in a given building project, the process of selecting a suitable construction method among different options is still made based on anecdotal evidence. Thus, it is imperative to evaluate the life cycle sustainability of different construction methods. The sustainability evaluation criteria (SEC) comprise the triple bottom line (TBL) sustainability categories, i.e., environmental, economic, and social, in which each category includes numerous sustainability performance indicators (SPI) associated with different life cycle phases of a building. The most significant step for comparative assessment of the life cycle sustainability of buildings is to develop suitable SPIs. In this paper, a methodology is used to identify and select the appropriate SPIs for life cycle sustainability evaluation of modular and conventional construction. Through a comprehensive literature review, 33 TBL SPIs were identified to address the life cycle sustainability performance of buildings. In order to investigate the applicability (importance) of the identified sustainability indicators when comparing the sustainability of modular and conventional buildings, a survey was designed and conducted. Subsequently, the construction professionals' perceptions of the applicability of these sustainability indicators were captured on a 5-point Likert scale. The reliability of questionnaire was analyzed using Cronbach's alpha measure. Then, all the SPIs were ranked based on their severity index (SI) values ranging between 20 and 100% correspond to a severity scale from “very low” to “extremely high” importance levels. All the SPIs were ranked under the overall TBL SPIs as well as within their associated sustainability categories. The analyses showed that 33% of the environmental SPIs, 67% of the economic SPIs, and 42% of the social SPIs were rated equal to or greater than “high” on severity scale (i.e., Severity Index ≥75%). The economic dimension of sustainability is still the governing concern of the construction industry practitioners. Moreover, the results revealed that attention to the social dimension of sustainability is increasing compared to the environmental dimension. This paper contributes to the current body of knowledge by highlighting the most applicable indicators for comparing and contrasting the sustainability of modular and conventional construction. [ABSTRACT FROM AUTHOR]
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- 2017
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4. A Multi-purpose countermeasure against image anti-forensics using autoregressive model.
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Zeng, Hui, Kang, Xiangui, and Peng, Anjie
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AUTOREGRESSIVE models , *DIGITAL image processing , *SUPPORT vector machines , *PERFORMANCE evaluation , *COMPARATIVE studies - Abstract
Image anti-forensics, which aims to remove or forge traces upon which image forensics is based, has made rapid progress recently. To rebuild the credibility of forensics, many countermeasures have been proposed for detecting different anti-forensics. However, most existing countermeasures just target only one type of anti-forensics and are difficult to extend to counter other anti-forensics. In this paper, a multi-purpose countermeasure using autoregressive (AR) model is proposed for detecting various anti-forensics. Experimental results demonstrate that the proposed countermeasure achieves satisfactory performance in detecting all of the five well-known anti-forensic methods discussed in this paper. Even compared to the state-of-art specific counter-measures, our proposed countermeasure achieves similar or better performance. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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5. A comparative study on performance and reliability of 32-bit binary adders.
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Bahadori, Milad, Kamal, Mehdi, Afzali-Kusha, Ali, and Pedram, Massoud
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ADDERS (Digital electronics) , *COMPARATIVE studies , *INTEGRATED circuits , *PERFORMANCE evaluation , *RELIABILITY in engineering - Abstract
In this paper, the performance and reliability of different binary adder families are studied for both the superthreshold and the near-threshold regions of operation. The adder structures are selected from both the carry propagate adders (CPAs) and parallel prefix adders (PPAs). The performance parameters which are used in the comparative study include delay, power, energy, and energy-delay-product (EDP) of the adders. Additionally, the impacts of the process variation and negative bias temperature instability (NBTI) on the delays of the adders under the aggressive supply voltage scaling are investigated. Also, the efficacies of the adders are compared using a merit function based on their performance and reliability parameters for a wide range of supply voltage levels, from the nominal voltage down to the near-threshold voltage. The study is performed for the 32-bit adder structures designed based on the 14-nm FinFET and 45-nm bulk CMOS technologies. The results which are obtained using HSPICE simulations, reveal that the reliability parameters similar to the performance parameters are a function of the adder architectures and those are the key components to determine the efficiencies of the adders. Also, the results show that the impacts of the process variation and NBTI on the delays of the high performance PPA structures are more than those of the CPA structures for the whole range of the supply voltage. The PPAs, however, have the higher merit factors compared to the CPAs under a wide range of supply voltage levels. The results presented in this paper may provide some guidelines for the designers to select proper adder structures based on their design requirements and constraints. [ABSTRACT FROM AUTHOR]
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- 2016
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6. Flattening: An efficient approach to improving the performance of conventional MINs.
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Rezazadeh, Majid, Safaei, Farshad, and Moazez, Mahsa
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TOPOLOGY , *NANOELECTRONICS , *PERFORMANCE evaluation , *CARBON nanotubes , *COMPARATIVE studies , *APPROXIMATION theory - Abstract
Numerous conventional interconnection networks have been designed in a way in which they use indirect or multistage topologies. The reason behind this idea is the fact that such topologies can minimize the network hop count. However, the constraints of technology and packaging have given impetus for fundamental changes in the approach to designing topologies. Increasing the radix of the network׳s routers lowers the total cost of the network, which is related to the number of routers׳ pins and connectors. This increase also results in lowering the power consumption, which plays a crucial role in the performance. Kim, Dally and Abts have provided a cost-efficient topology for high-radix networks, named the flattened Butterfly. They have shown that this approach is comparable to the conventional Butterfly networks with regard to cost. It is much the same as a Folded-Clos topology in terms of the performance per cost ratio under adversarial traffic, whilst under benign traffic, the flattened Butterfly has approximately twice this ratio. In this paper, we have generalized the idea of flattening to all Delta networks, in addition to some non-Delta ones such as Beneš and Clos. Moreover, the conditions on which multistage networks can be converted to the flattened ones have been generally provided. All the mentioned networks have also been compared with another cost-efficient topology, named the HyperX, in order to gain deep insight into the key facets of the microarchitecture of high-radix networks. On the other hand, advances in designing digital circuits and reduction in their size rely upon knowledge in nano-electronics for refinements of the standard copper interconnect technology. This copper interconnects have become a major performance bottleneck in Multistage Interconnection Network (MIN) platforms. Consequently, a minor contribution of this paper is the performance assessment of the aforementioned networks using the Carbon NanoTube (CNT) technology under trace-driven and synthetic traffic patterns; inasmuch as this technology has been introduced as one of the six most important architectures in future digital systems. CNT is considered to be a promising technology in the design and fabrication of the next-generation chips since it is capable of handling extremely high current densities for a long time without considerable performance degradation. Although the comparative study of different networks with various parameters is the main goal, it should be taken into consideration that in some situations, these parameters provide similar conditions in different networks. As such, they can be combined with an efficient method to present a simple model. Finally, we have used data mining in order to reach a unified and meaningful performance parameter. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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7. Transmission line protection systems with aided communication channels—Part II: Comparative performance analysis.
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dos Santos, André, Barros, M.T. Correia de, and Correia, P.F.
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ELECTRIC power transmission , *COMPARATIVE studies , *PERFORMANCE evaluation , *COST analysis , *MONTE Carlo method - Abstract
Following the Part I paper, a comparative performance analysis is presented, considering four different transmission line protection schemes, equipped with aided communication channels. In the Part I paper, the performance analysis methodology was presented, which is based on a probabilistic approach to protection system successful operation. The system performance takes in account equipment reliability factors such as failure rate and time to repair, and is assessed by the availability index. In the present paper, new performance indicators are introduced, which are applicable to transmission line protection system design, as well as to describe its probabilistic operation in other power system studies. Four different transmission line protection schemes with aided communication channels, operating in today's transmission networks, are compared. The results obtained for the performance indicators allow quantifying the benefits of the different design options. In particular, the effect of relay and communication channel redundancy, as well as communication channel sharing, is highlighted. Furthermore, results show that the newly defined performance indicators can be used in a cost/benefit analysis, as well as to assess maintenance strategies and communication reliability requirements. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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8. Evaluating the efficiency performance of airports using an integrated AHP/DEA-AR technique.
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Lai, Po‐Lin, Potter, Andrew, Beynon, Malcolm, and Beresford, Anthony
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AIRPORTS , *PERFORMANCE evaluation , *ANALYTIC hierarchy process , *DATA envelopment analysis , *ECONOMETRICS , *COMPARATIVE studies - Abstract
Airport efficiency is an area of increasing interest to academics, policy makers and practitioners. This has resulted in a body of literature applying various econometric techniques to compare efficiency between different samples of airports. This paper uses the multi-criteria decision making method Analytic Hierarchy Process (AHP) to incorporate the weightings of input and output variables into Data Envelopment Analysis (DEA) and Assurance Region DEA (DEA-AR) models, with 24 major international airports in the empirical analysis. The paper concludes the discriminatory power in the proposed AHP/DEA-AR model is greater than in the basic DEA model when measuring the efficiency of airports. By applying this approach, policy makers and practitioners can effectively compare operational efficiency between airports, and therefore generate more informed decisions. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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9. Finding region of interest in the infrared image of electrical installation.
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Jadin, Mohd Shawal, Taib, Soib, and Ghazali, Kamarul Hawari
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ELECTRIC appliance installation , *INFRARED imaging , *THERMAL analysis , *IMAGE segmentation , *COMPARATIVE studies , *PERFORMANCE evaluation - Abstract
This paper presents a method of automatically finding the region of interests (ROIs) in an infrared image of electrical installations. These regions are very important, particularly for diagnosing the thermal condition of electrical equipment. For a vast number of electrical equipment to be inspected, manual region selection of the images normally will take a lot of time. Therefore, an automatic region detection system is more preferred. However, due to the nature of the infrared image, the conventional segmentation methods have some limitations in order to properly find the desired ROIs. In addition, all objects within the image commonly have heterogeneous pixel intensities causing the segmented regions tend to be over segmented or some parts of the target objects either be divided into multiple regions or merging with the background image. Therefore, this paper proposes a new segmentation method of detecting the repeated structures of electrical equipment within an infrared image by taking the advantage of local keypoint feature matching. Experimental results indicate that the proposed method achieves a better performance for detecting the target ROIs compared with the conventional methods. The algorithm was tested on real infrared images with diverse irregular intensity variations and cluttered background. Finally, the performance of the proposed method was qualitatively and quantitatively evaluated. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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10. A performance evaluation of three inference engines as expert systems for failure mode identification in shafts.
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Moreno, Carlos Javier and Espejo, Edgar
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PERFORMANCE evaluation , *INFERENCE engines (Computer science) , *EXPERT systems , *SHAFTS (Excavations) , *COMPARATIVE studies - Abstract
This paper aims to present performance evaluation of three different inference engines (rule based reasoning, fuzzy based reasoning and Bayesian based reasoning) for failure mode identification in shafts. This research was done with a focus on the validation cases and results after their use in failure cases from several industries where the three systems were tested under the same conditions. Each system was implemented using the same user interface and knowledge base, with different frameworks and techniques as follows: rule based inference reasoning (prolog, C#), Mamdani-fuzzy based reasoning (C, MATLAB®) and Bayesian based reasoning with a variable elimination algorithm (C, MATLAB®). The best performance was obtained using the Bayesian inference engine. The conditional probabilities give flexibility when evidence is not listed, while the fuzzy and classical IF-THEN systems depend on the rules in the inference engine. The process presented in this paper could be used for validation of any expert system or for comparison with other expert systems (inference engines) when the knowledge base is the same. [ABSTRACT FROM AUTHOR]
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- 2015
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11. A comparison of feature description algorithms.
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Hu, Jinlong, Peng, Xianrong, and Fu, Chengyu
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FEATURE extraction , *COMPARATIVE studies , *ALGORITHMS , *QUANTITATIVE research , *PERFORMANCE evaluation - Abstract
This paper reviews and evaluates several state-of-the-art feature description algorithms. The components of each feature description method are analyzed and their applications in dealing with specific challenges are identified. In the paper, we compare state-of-the-art feature description methods including the SIFT, DAISY, HRI-CSLTP, LIOP, MROGH and MRRID with specific measurement regulation. The quantitative comparative results demonstrate these algorithms’ applications in different scenes, which provide a certain guide for designing novel feature description algorithms. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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12. Design and performance analysis of a hybrid solar tricycle for a sustainable local commute.
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Paudel, Ananda Mani and Kreutzmann, Philipp
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SUSTAINABLE development , *HYBRID solar cells , *FOSSIL fuels , *PERFORMANCE evaluation , *CARBON dioxide mitigation , *COMPARATIVE studies - Abstract
Fossil-fueled transportation is the main type of transportation used all over the world. Transportation in the United States consumes almost one third of global transportation energy and is one of the major contributors to CO 2 emissions. To deal with ever increasing environmental pollution and reduce energy consumption, a solar Trike design is presented in this paper to offer an alternative means of transportation. The solar Trike offers a higher occupancy rate, speed and travel range that can satisfy the needs of the local commute. The design, economics, sustainability and performance analysis of the solar Trike is presented in this paper. The dimension and power requirement of the solar-powered tricycle was determined based on aerodynamic force, rolling resistance, expected payload, travel velocity and distance and solar irradiance. A CAD model was built and analyzed for sustainability before building the prototype. Test run results of the prototype suggested the technical feasibility and practical applicability of the design. An LCA was performed to evaluate environmental impacts during various stages of the product life: manufacturing to disposal using SolidWorks Sustainability software. Manufacturing, operating and environmental costs are analyzed for economic viability of the design. The annual costs of CO 2 emissions, design and installation, annual maintenance, and costs to store the power for one full charge amount to $417. With a travel range of 37.1 km on a full charge, the proposed solar-powered tricycle is able to meet more than 90% of all trip distances in the USA. The proposed solar powered tricycle reduces energy consumption by more than 41%, as well as decreases CO 2 emissions by more than 75%, in comparison with the railroad, the best mode of existing transportation. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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13. Minimum failure cost-based energy dissipation system designs for buildings in three seismic regions - Part I: Elements of failure cost analysis.
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Shin, H. and Singh, M. P.
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FAILURE analysis , *PERFORMANCE evaluation , *EARTHQUAKE resistant design , *COMPARATIVE studies , *ESTIMATION theory , *VISCOSITY - Abstract
This and the companion papers are focused on the optimal utilization of viscous dampers for performance improvement of building structures by minimizing the failure/life-cycle costs. The cost minimization is a natural choice as the primary motivation for introducing the multi-objective performance based design concept in the earthquake engineering community was to reduce the observed unacceptable levels of damage costs in buildings for moderate intensity but more frequent earthquakes. This paper describes an approach to calculate the failure and life-cycle costs associated with different levels of damage and their consequences considering the random occurrences of seismic events and uncertainties in the calculated response. The inter-story drift is used as an effective response variable to define fragilities and failure costs, although it is realized that damage of some components may be better expressed in terms of the acceleration response. Since a life-cycle cost-based optimization methodology could be computationally demanding especially for yielding structures, the use a response spectrum method of analysis is considered for the response and failure cost calculations. Comparison of the numerical results, for three example buildings in Los Angeles, Seattle and Boston, obtained by the approximate response spectrum method and accurate time-stepping method utilizing an ensemble of base motions indicates that the response spectrum methods can provide a good estimate of the failure cost for a quick performance-based evaluation of different design alternatives. The companion paper utilizes this failure cost and performance evaluation approach to determine optimal designs of damping systems. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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14. Geometric optimization of X-shaped cavities and pathways according to Bejan’s theory: Comparative analysis.
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Lorenzini, G., Biserni, C., and Rocha, L.A.O.
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THERMAL conductivity , *MATHEMATICAL optimization , *TEMPERATURE effect , *THICKNESS measurement , *COMPARATIVE studies , *PERFORMANCE evaluation - Abstract
Abstract: This paper applies constructal design to study the geometry of a X-shaped isothermal cavity and a X-shaped high conductivity pathway that penetrate into a solid conducting wall. The objective is to minimize the maximal excess of temperature of the whole system, i.e. the hot spots, independent of where they are located. There is uniform heat generation on the solid body, which is insulated on the external perimeter. The total volume and the cavity volume, as well as the high conductivity material volume, are fixed, but the geometric lengths and thickness of both X-shaped configurations can vary. The emerged optimal configurations and performance are reported graphically and numerically. The results indicate that the increase of the complexity of the geometry can facilitate the access of heat currents and improve the thermal performance. The degree of freedom L 1/L 0 proved to be significant on the performance of the X-shaped isothermal cavity, e.g. the once optimized ratio (L 1/L 0)o increases approximately 10% as the area fraction ϕ increases from ϕ =0.05 to 0.3. As for the X-shaped pathway case, it has been demonstrated that the dimensionless thermal conductivity of the path and the area fraction ϕ have a strong effect on the performance and configuration of the X-shaped blades: the twice minimized θ max,mm decreases approximately 70% as increases from 30 to 300 and it decreases approximately 84% as ϕ augments from 0.01 to 0.2. Furthermore, the X-shaped conductive pathways configuration increases its performance monotonically with the augmentation of the pathways thermal conductivity: in correspondence to the highest possible value of , the X-shaped conductive pathways present approximately the same heat removal capacity of the X-shaped cavities optimized in the first part of the paper. [Copyright &y& Elsevier]
- Published
- 2014
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15. A segmentation based channel scheduling scheme for improving channel utilization in OBS networks.
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Mandloi, A. and Mishra, V.
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IMAGE segmentation , *OPTICAL switching , *COMPARATIVE studies , *SIMULATION methods & models , *PERFORMANCE evaluation - Abstract
Abstract: Channel scheduling is an important aspect in optical burst switching (OBS) networks. OBS is a promising solution for the future Internet backbone. In OBS network a key issue is data channel scheduling. In this paper we propose a channel scheduling scheme to optimize channel utilization for OBS networks with segmentation. In this paper, we propose an efficient way to organize the void intervals. The channel scheduling method is compared with existing scheduling schemes. Simulation results show that both channel utilization and burst loss ratio performance improved as compared to existing scheduling schemes. [Copyright &y& Elsevier]
- Published
- 2014
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16. Recognizing activities in multiple views with fusion of frame judgments.
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Pehlivan, Selen and Forsyth, David A.
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HUMAN activity recognition , *MULTISENSOR data fusion , *IMAGE reconstruction , *THREE-dimensional imaging , *PERFORMANCE evaluation , *COMPARATIVE studies - Abstract
Abstract: This paper focuses on activity recognition when multiple views are available. In the literature, this is often performed using two different approaches. In the first one, the systems build a 3D reconstruction and match that. However, there are practical disadvantages to this methodology since a sufficient number of overlapping views is needed to reconstruct, and one must calibrate the cameras. A simpler alternative is to match the frames individually. This offers significant advantages in the system architecture (e.g., it is easy to incorporate new features and camera dropouts can be tolerated). In this paper, the second approach is employed and a novel fusion method is proposed. Our fusion method collects the activity labels over frames and cameras, and then fuses activity judgments as the sequence label. It is shown that there is no performance penalty when a straightforward weighted voting scheme is used. In particular, when there are enough overlapping views to generate a volumetric reconstruction, our recognition performance is comparable with that produced by volumetric reconstructions. However, if the overlapping views are not adequate, the performance degrades fairly gracefully, even in cases where test and training views do not overlap. [Copyright &y& Elsevier]
- Published
- 2014
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17. A mixed framework for transform domain Wyner–Ziv video coding.
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Rup, Suvendu and Majhi, Banshidhar
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VIDEO coding , *PERFORMANCE evaluation , *MULTILAYER perceptrons , *COMPARATIVE studies , *IMAGE quality analysis , *DIFFRACTION patterns - Abstract
Abstract: This paper presents a mixed framework based on an efficient intra key frame coding and an improved side information (SI) generation scheme in transform domain Wyner–Ziv (WZ) video coding. The performance of the WZ video coding strongly depends on the quality of the SI. The SI can be generated from the decoded key frames resulted from intra key frame video coding. The better the decoded key frames are the better would be the SI generation. In this paper, a Burrows–Wheeler transform (BWT) based intra-frame video coding is proposed to generate improved decoded key frames. Furthermore, an improved SI generation scheme with multilayer perceptron (MLP) is proposed. Comparative analysis with other standard techniques of WZ video coding reveals that the proposed scheme has better standing as compared to its counterparts in terms of both coding efficiency and improved perceptual quality. [Copyright &y& Elsevier]
- Published
- 2013
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18. Evaluating the characteristics of a non-standardised Model Requirements Analysis (MRA) for the development of policy impact assessment tools.
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Sieber, S., Amjath-Babu, T.S., McIntosh, B.S., Tscherning, K., Müller, K., Helming, K., Pohle, D., Fricke, K., Verweij, P., Pacini, C., Jansson, T., and Gomez y Paloma, S.
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CRITICAL analysis , *ENVIRONMENTAL policy , *COMPARATIVE studies , *EMBEDDINGS (Mathematics) , *PERFORMANCE evaluation , *COMPUTER networks - Abstract
Abstract: The aim of this paper is to provide a critical analysis of the strengths and weaknesses of a non-standardised Model Requirements Analysis (MRA) used for the purpose of developing the Sustainability Impact Assessment Tool (SIAT). By ‘non-standardised’ we mean not strictly following a published MRA method. The underlying question we are interested in addressing is how non-standardised methods, often employed in research driven projects, compare to defined methods with more standardised structure, with regards their ability to capture model requirements effectively, and with regards their overall usability. Through describing and critically assessing the specific features of the non-standardised MRA employed, the ambition of this paper is to provide insights useful for impact assessment tool (IAT) development. Specifically, the paper will (i) characterise kinds of user requirements relevant to the functionality and design of IATs; (ii) highlight the strengths and weaknesses of non-standardised MRA for user requirements capture, analysis and reflection in the context of IAT; (iii) critically reflect on the process and outcomes of having used a non-standardised MRA in comparison with other more standardised approaches. To accomplish these aims, we first review methods available for IAT development before describing the SIAT development process, including the MRA employed. Major strengths and weaknesses of the MRA method are then discussed in terms of user identification and characterisation, organisational characterisation and embedding, and ability to capture design options for ensuring usability and usefulness. A detailed assessment on the structural differences of MRA with two advanced approaches (Integrated DSS design and goal directed design) and their role in performance of the MRA tool is used to critique the approach employed. The results show that MRA is able to bring thematic integration, establish system performance and technical thresholds as well as detailing quality and transparency guidelines. Nevertheless the discussion points out to a number of deficiencies in application - (i) a need to more effectively characterise potential users, and; (ii) a need to better foster communication among the distinguished roles in the development process. If addressed these deficiencies, SIAT non-standardised MRA could have brought out better outcomes in terms of tool usability and usefulness, and improved embedding of the tool into conditions of targeted end-users. [Copyright &y& Elsevier]
- Published
- 2013
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19. Comparison study on different SOFC hybrid systems with zero-CO2 emission.
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Duan, Liqiang, Huang, Kexin, Zhang, Xiaoyuan, and Yang, Yongping
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SOLID oxide fuel cells , *CARBON dioxide mitigation , *COMPARATIVE studies , *EXERGY , *CARBON sequestration , *PERFORMANCE evaluation - Abstract
Abstract: Based on a traditional SOFC (solid oxide fuel cell) hybrid power system, three different SOFC hybrid power systems with zero-CO2 emission are proposed in this paper and their performances are analyzed and compared. The anode outlet gas of SOFC burns with the pure oxygen and the concentration of CO2 is greatly increased. In order to maintain the appropriate turbine inlet temperature, three different measures (steam injection, CO2 gas injection and heat exchange layout) are taken. Because the outlet flue gas of the afterburner mainly consists of CO2 and steam, the CO2 in the flue gas can be captured easily by the condensation method after the recovery of work and heat. With the exergy analysis method, this paper studies the exergy loss distributions of every unit of SOFC hybrid systems with CO2 capture and reveals the variation rules of exergy loss distributions. The effects of the main operating parameters on the overall performances of SOFC hybrid systems with CO2 capture are also investigated. The results show that the zero CO2 emission SOFC hybrid systems still have higher efficiencies, which only decrease about 3–4% compared with that of the basic SOFC hybrid system without CO2 capture. [Copyright &y& Elsevier]
- Published
- 2013
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20. Intensification principle of a new three-phase catalytic slurry reactor. Part II: Eco-efficiency and techno-economic performances.
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Machefer, Stephan, Falk, Laurent, and de Panthou, Fabrice
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CHEMICAL reactors , *MULTIPHASE flow , *HYDROGENATION , *PERFORMANCE evaluation , *MASS transfer , *COMPARATIVE studies - Abstract
In two papers, the concept and the performances of a new continuous intensified reactor named RAPTOR® (French acronym for Reactor with Polyvalent Rectilinear Stirred Reactor with Optimised Transfer) are presented. Based on flow, heat and mass transfer characterisations and real hydrogenation experiments, Paper I presented a simple analytical model based on characteristic times that enables to explain the intensified performances compared with a semi-batch stirred reactor and to generalise the operability, rapidity and the flexibility of this minireactor. In Paper II (this article), the model is used to evaluate in a comparative study the eco-efficiency and the techno-economical advantages of a continuous process involving a RAPTOR® versus a classical batch process equipped with a stirred reactor. Economical, environmental aspects are considered as well as productivity, safety and process control. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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21. Self Explaining Roads and situation awareness
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Walker, Guy H., Stanton, Neville A., and Chowdhury, Ipshita
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ROAD safety measures , *SITUATIONAL awareness , *EXPRESS highways , *TRAFFIC safety , *PERFORMANCE evaluation , *COMPARATIVE studies - Abstract
Abstract: This paper places theories of SA into contact with the issue of Self Explaining Roads. Twelve drivers took part in an on-road study and performed a verbal commentary as they drove around a defined test route. The verbal transcripts were partitioned into six road types, and driver SA was modeled using semantic networks. The content and structure of these networks was analysed and cognitively salient endemic road features were extracted. These were then compared with aspects of driver behaviour. The findings highlight the systemic nature of the driver–vehicle–road interaction, and show that SA is highly contingent on road type. The findings also reveal that motorways/freeways are the most cognitively compatible road type and that incompatibilities grow rapidly as road types become increasingly minor and less overtly ‘designed’. The paper is exploratory in nature but succeeds in innovating a theoretically robust means of examining road environments under naturalistic conditions. It also succeeds in providing numerous insights and hypotheses for a developing program of work. [Copyright &y& Elsevier]
- Published
- 2013
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22. Experimental validation of a semi-dynamic simplified model of active pipe-embedded building envelope.
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Zhu, Qiuyuan, Li, Anbang, Xie, Junlong, Li, Weiguang, and Xu, Xinhua
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BUILDING envelopes , *STRUCTURAL engineering , *HEAT transfer , *THERMODYNAMICS of pipe , *PERFORMANCE evaluation , *THERMAL analysis , *COMPARATIVE studies , *WATER temperature - Abstract
Active pipe-embedded building envelope can allow for substantial heat flow for relatively small temperature difference due to the embedded pipes in the external wall/roof. This structure can directly utilize the low-grade sources for reducing building cooling/heating load and improving indoor thermal comfort by intercepting the heat gain/loss through the building envelope due to the circular water inside the embedded pipe. This paper presents the experimental validation of a semi-dynamic simplified model of the active pipe embedded building envelope. The experiment test rig consists of two environment chambers with one for simulating the ambient environment and one for indoor environment with a pipe-embedded building envelope sample separating both chambers. A small chiller and a buffer tank are installed to provide stable water temperature for the test sample. The temperatures and heat fluxes on both sides of the test sample, the inlet and outlet water temperature as well as flow rate are measured. The measured boundary conditions are used as the inputs of the semi-dynamic simplified model for calculating the thermal performance of the active structure. The results show the semi-dynamic simplified model can predict the semi-steady or pure dynamic thermal performance of the pipe-embedded building envelope very well by comparing with the measurement. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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23. Comparison of ejector predicted performance by thermodynamic and CFD models.
- Author
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Croquer, Sergio, Poncet, Sébastien, and Galanis, Nicolas
- Subjects
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COMPARATIVE studies , *EJECTOR pumps , *PERFORMANCE evaluation , *THERMODYNAMICS , *COMPUTATIONAL fluid dynamics , *PREDICTION models - Abstract
This paper presents a systematic comparison of ejector performance predictions by a thermodynamic and a CFD model for different operating conditions. The dimensions of the ejector were determined by the thermodynamic model and used in the CFD model. The thermodynamic model predicts higher entrainment ratios for double choking operation and somewhat different values of the critical and limiting pressure ratios. The CFD model validates the similarity solutions characteristic of ejectors using perfect gases. It also shows that the position of the shock varies linearly with the compression ratio in qualitative agreement with the assumption used in the thermodynamic model. Finally, the isentropic and mixing efficiencies obtained by the two approaches are favorably compared. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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24. Influence of failure modes on PEFC stack and single cell performance and durability.
- Author
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Radev, Ivan, Koutzarov, Krassimir, Lefterova, Elefteria, and Tsotridis, Georgios
- Subjects
- *
PROTON exchange membrane fuel cells , *PERFORMANCE evaluation , *DURABILITY , *SHORT-circuit currents , *FAILURE analysis , *HYDROGEN storage , *COMPARATIVE studies , *HUMIDITY - Abstract
Abstract: The paper reports on the influence of low humidity, short-circuiting, hydrogen starvation and open circuit potential on the performance and service life of 11 kW PEFC stack and 25 cm2 single cell. The failure modes in PEFC stack were caused by series of laboratory and software shortcomings during the tests, while tests in a single PEFC were performed for comparison purpose. Due to the impossibility to predict the influence of the failure modes on PEFC stack performance and durability based solely on the results obtained in a single PEFC demonstrated in the paper and having in mind the cost of a high power PEFC stack there is a lack of systematic knowledge in the field. The failure modes' influence was investigated in detail on the performance of the overall PEFC stack, individually on each membrane electrode assembly (MEA) in the stack and on the single PEFC. The reasons for MEAs failures were explained and recommendations for PEFC stack rehabilitation were given. By analyzing the reasons and shortcomings causing the failure modes the paper also provides information on some specifics in coupling and communication between some conditioning and testing devices. [Copyright &y& Elsevier]
- Published
- 2013
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25. Multicast based Proxy Mobile IPv6 for inter-domain handover.
- Author
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Kim, Chaehwan, Hwang, Hyunwoo, Baik, Jung-Woo, and Lee, Kyung-Geun
- Subjects
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COMPUTER networks , *INTERNET service providers , *PERFORMANCE evaluation , *COMPARATIVE studies , *COMPUTER systems - Abstract
Abstract: IETF has proposed the use of PMIPv6 in the IP network in order to reduce the latency of intra-domain handover and to enable handover in the Mobile Node (MN). However, since PMIPv6 does not support inter-domain handover, IETF is considering the use of the previously proposed method, MIPv6, for inter-domain handover (Giaretta et al., 2010) [4]. This paper proposes a new method of enabling inter-domain handover with just PMIPv6 by adding a multicast server to it. Adding the multicast server keeps the L4 connection in both intra and inter-domains and supports the handover of MN, which originally is not supported. Also, it enables the IP service to remain connected anywhere without having to modify the previous application. In addition, this method allows lower latency intra-domain handover than MIPv6. To prove the effectiveness of this proposed method, the comparison between the performance of PMIPv6 and MIPv6 for the intra-domain and inter-domain is shown in this paper. [Copyright &y& Elsevier]
- Published
- 2013
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26. Effective accelerometer test beds for output enhancement of an inertial navigation system
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Kamer, Y. and Ikizoglu, S.
- Subjects
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ACCELEROMETERS , *ELECTROMECHANICAL devices , *COMPARATIVE studies , *ACQUISITION of data , *ARTIFICIAL neural networks , *PERFORMANCE evaluation - Abstract
Abstract: This paper is submitted upon a research to enhance the output of an accelerometer widely used in inertial navigation units. In our study we introduce relatively simple and effective test beds to collect accurate and diverse reference data. We also carried out calibration runs with a highly accurate electromechanical shaking table. The proposed test beds compare well with sophisticated counterparts. The collected data is used to train artificial neural networks (ANNs) which would improve the accelerometer outputs by estimating the reference data from the actual sensor outputs. The ANN performance is compared with classic low pass filtering methods to provide a relative performance criterion. In this paper we focus on test beds rather than to give the details of the whole study. The test beds introduced in this research can be used for acquiring reference data for implementation of other different filter methods as well. [Copyright &y& Elsevier]
- Published
- 2013
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27. PalmHash Code vs. PalmPhasor Code
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Leng, Lu and Zhang, Jiashu
- Subjects
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PALMPRINTS , *PERFORMANCE evaluation , *CODING theory , *COMPARATIVE studies , *COMPUTATIONAL complexity , *INFORMATION storage & retrieval systems , *COMPUTER security - Abstract
Abstract: The existing palmprint protection schemes without verification degrading do not strictly meet non-invertible requirement; while non-invertible palmprint protection schemes do not meet verification performance requirement in stolen-token scenario. PalmHash Code and PalmPhasor Code, as two cancelable palmprint coding schemes, are proposed in this paper to balance the conflict between security and verification performance. In order to reduce computational complexity and storage cost, cancelable palmprint coding frameworks are extended from one dimension to two dimensions. Besides, two measures, perpendicular orientation transposition and multi-orientation score level fusion, are employed to further improve the performance of two dimensional (2D) cancelable palmprint codes. PalmHash Code and PalmPhasor Code are compared extensively in this paper. The experimental results and analysis confirm that 2D PalmHash Code and 2D PalmPhasor Code enhanced by the two measures are effective and secure even in stolen-token scenario. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
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28. The performance evaluation of a spectrum sensing implementation using an automatic modulation classification detection method with a Universal Software Radio Peripheral
- Author
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Popoola, Jide Julius and van Olst, Rex
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REMOTE sensing , *CLASSIFICATION , *WIRELESS communications , *SOFTWARE radio , *ARTIFICIAL neural networks , *INFORMATION theory , *COMPARATIVE studies , *PERFORMANCE evaluation - Abstract
Abstract: Based on the inherent capability of automatic modulation classification (AMC), a new spectrum sensing method is proposed in this paper that can detect all forms of primary users’ signals in a cognitive radio environment. The study presented in this paper focuses on the sensing of some combined analog and digitally primary modulated signals. In achieving this objective, a combined analog and digital automatic modulation classifier was developed using an artificial neural network (ANN). The ANN classifier was combined with a GNU Radio and Universal Software Radio Peripheral version 2 (USRP2) to develop the Cognitive Radio Engine (CRE) for detecting primary users’ signals in a cognitive radio environment. The detailed information on the development and performance of the CRE are presented in this paper. The performance evaluation of the developed CRE shows that the engine can reliably detect all the primary modulated signals considered. Comparative performance evaluation carried out on the detection method presented in this paper shows that the proposed detection method performs favorably against the energy detection method currently acclaimed the best detection method. The study results reveal that a single detection method that can reliably detect all forms of primary radio signals in a cognitive radio environment, can only be developed if a feature common to all radio signals is used in its development rather than using features that are peculiar to certain signal types only. [Copyright &y& Elsevier]
- Published
- 2013
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29. Performance analysis of colour descriptors for parquet sorting
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Bianconi, Francesco, Fernández, Antonio, González, Elena, and Saetta, Stefano A.
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PERFORMANCE evaluation , *SORTING (Electronic computers) , *COMPARATIVE studies , *REAL-time computing , *PROBLEM solving , *ACCURACY of information , *EXPERT systems , *STATISTICS - Abstract
Abstract: In this paper we consider the problem of colour-based sorting hardwood parquet slabs into lots of similar visual appearance. As a basis for the development of an expert system to perform this task, we experimentally investigate and compare the performance of various colour descriptors (i.e.: soft descriptors, percentiles, marginal histograms and 3D histogram), and colour spaces (i.e.: RGB, HSV and CIE Lab). The results show that simple and compact colour descriptors, such as the mean of each colour channel, are as accurate as more complicated features. Likewise, we found no statistically significant difference in the accuracy attainable through the colour spaces considered in the paper. Our experiments also show that most methods are fast enough for real-time processing. The results suggest the use of simple statistical descriptors along with RGB data as the best practice to approach the problem. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
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30. A window of opportunity: Assessing behavioural scoring
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Kennedy, K., Mac Namee, B., Delany, S.J., O’Sullivan, M., and Watson, N.
- Subjects
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MONEYLENDERS , *MAXIMUM likelihood statistics , *REPAYMENTS , *PERFORMANCE evaluation , *EXPERT systems , *SENSITIVITY analysis , *COMPARATIVE studies - Abstract
Abstract: After credit has been granted, lenders use behavioural scoring to assess the likelihood of default occurring during some specific outcome period. This assessment is based on customers’ repayment performance over a given fixed period. Often the outcome period and fixed performance period are arbitrarily selected, causing instability in making predictions. Behavioural scoring has failed to receive the same attention from researchers as application scoring. The bias for application scoring research can be attributed, in part, to the large volume of data required for behavioural scoring studies. Furthermore, the commercial sensitivities associated with such a large pool of customer data often prohibits the publication of work in this area. This paper focuses on behavioural scoring and evaluates the contrasting effects of altering the performance period and outcome period using 7-years worth of data from the Irish market. The results of this work indicate that a 12-month performance period yields an easier prediction task when compared with other historical payment periods of varying lengths. This article also quantifies differences in the classification performance of logistic regression arising from different outcome periods length. Our findings show that the performance of a logistic regression classifier degrades significantly when the outcome window is extended beyond 6-month. Finally we consider different approaches to how the concept of default is defined. Typically whether the customer is identified as a default risk or not is set based on either (i) whether the account is in default at the end of the outcome period or (ii) at any time during the outcome period. This paper studies both approaches and finds that the latter approach resulted in an easier classification problem, that is, it gives the highest assurance that the classification will be correct. [Copyright &y& Elsevier]
- Published
- 2013
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31. The spectral element method for static neutron transport in A N approximation. Part I
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Barbarino, A., Dulla, S., Mund, E.H., and Ravetto, P.
- Subjects
- *
NEUTRON transport theory , *FINITE element method , *TRANSPORTATION problems (Programming) , *NUMERICAL analysis , *PERFORMANCE evaluation , *STOCHASTIC convergence , *COMPARATIVE studies - Abstract
Abstract: Spectral elements methods provide very accurate solutions of elliptic problems. In this paper we apply the method to the A N (i.e. SP2N−1) approximation of neutron transport. Numerical results for classical benchmark cases highlight its performance in comparison with finite element computations, in terms of accuracy per degree of freedom and convergence rate. All calculations presented in this paper refer to two-dimensional problems. The method can easily be extended to three-dimensional cases. The results illustrate promising features of the method for more complex transport problems. [Copyright &y& Elsevier]
- Published
- 2013
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32. A comparative analysis between contractors’ and inspectors’ perceptions of the department of labour occupational health and safety inspectorate relative to South African construction
- Author
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Geminiani, F.L., Smallwood, J.J., and Fee, S.
- Subjects
- *
CONSTRUCTION industry , *CONTRACTORS , *INDUSTRIAL hygiene , *QUALITY control inspectors , *COMPARATIVE studies , *INFORMATION theory , *PERFORMANCE evaluation - Abstract
Abstract: A doctoral study was conducted with the aim of investigating the effectiveness and performance of the Department of Labour (DoL) Occupational Health and Safety (OH&S) Inspectorate in South Africa. Information was sought and obtained from various respondents including building and civil contractors, OH&S consultants, project managers, DoL inspectors, and designers by means of a questionnaire survey. The salient findings of the study elucidate that the DoL OH&S Inspectorate is not perceived as effective in terms of OH&S or as a means of assuring compliance according to contractors in South Africa. This paper presents a comparative analysis of the perceptions of the contractors and the Department of Labour (DoL) inspectors in terms of the performance of the DoL OH&S Inspectorate. Mean scores, mean rankings, t-values and p-values enabled the perceptions of the two stakeholder groups to be analysed. Analysis of the contractors’ mean responses and the inspectors’ mean responses revealed that six of the ten performance aspects had statistically significantly different mean scores, highlighting the contractors’ perceptions as statistically significantly different to the inspectors’ perceptions. This paper provides a discussion of the performance aspects relative to the DoL Inspectorate’s responsibility of assuring OH&S, and benchmarks the current gap in perceptions between inspectors and contractors in South Africa. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
33. A comparison of methods for non-rigid 3D shape retrieval
- Author
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Lian, Zhouhui, Godil, Afzal, Bustos, Benjamin, Daoudi, Mohamed, Hermans, Jeroen, Kawamura, Shun, Kurita, Yukinori, Lavoué, Guillaume, Van Nguyen, Hien, Ohbuchi, Ryutarou, Ohkita, Yuki, Ohishi, Yuya, Porikli, Fatih, Reuter, Martin, Sipiran, Ivan, Smeets, Dirk, Suetens, Paul, Tabia, Hedi, and Vandermeulen, Dirk
- Subjects
- *
COMPARATIVE studies , *THREE-dimensional imaging , *IMAGE retrieval , *PERFORMANCE evaluation , *CLASSIFICATION , *ALGORITHMS - Abstract
Abstract: Non-rigid 3D shape retrieval has become an active and important research topic in content-based 3D object retrieval. The aim of this paper is to measure and compare the performance of state-of-the-art methods for non-rigid 3D shape retrieval. The paper develops a new benchmark consisting of 600 non-rigid 3D watertight meshes, which are equally classified into 30 categories, to carry out experiments for 11 different algorithms, whose retrieval accuracies are evaluated using six commonly utilized measures. Models and evaluation tools of the new benchmark are publicly available on our web site . [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
34. Computational intelligence for heart disease diagnosis: A medical knowledge driven approach
- Author
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Nahar, Jesmin, Imam, Tasadduq, Tickle, Kevin S., and Chen, Yi-Ping Phoebe
- Subjects
- *
HEART disease diagnosis , *COMPUTATIONAL intelligence , *PERFORMANCE evaluation , *CLASSIFICATION , *COMPARATIVE studies , *BINARY number system , *RANKING (Statistics) , *DATA analysis - Abstract
Abstract: This paper investigates a number of computational intelligence techniques in the detection of heart disease. Particularly, comparison of six well known classifiers for the well used Cleveland data is performed. Further, this paper highlights the potential of an expert judgment based (i.e., medical knowledge driven) feature selection process (termed as MFS), and compare against the generally employed computational intelligence based feature selection mechanism. Also, this article recognizes that the publicly available Cleveland data becomes imbalanced when considering binary classification. Performance of classifiers, and also the potential of MFS are investigated considering this imbalanced data issue. The experimental results demonstrate that the use of MFS noticeably improved the performance, especially in terms of accuracy, for most of the classifiers considered and for majority of the datasets (generated by converting the Cleveland dataset for binary classification). MFS combined with the computerized feature selection process (CFS) has also been investigated and showed encouraging results particularly for NaiveBayes, IBK and SMO. In summary, the medical knowledge based feature selection method has shown promise for use in heart disease diagnostics. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
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35. Hierarchy-based reversible data hiding
- Author
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Huang, Hsiang-Cheh and Chang, Feng-Cheng
- Subjects
- *
PIXELS , *ALGORITHMS , *CODING theory , *IMAGE quality analysis , *SIMULATION methods & models , *PERFORMANCE evaluation , *COMPARATIVE studies , *DATA analysis - Abstract
Abstract: In this paper, we propose a new method for reversible data hiding by employing the hierarchical relationships of original images. There are many parameters for accessing the performances of reversible data hiding algorithms, including the output image quality, the hiding capacity, and the overhead for decoding. Considering the ease of implementation and the little overhead needed for decoding, we employ modification of difference values between pixels by using histogram-based scheme with extensions to pyramidal structure by utilizing inherent characteristics of original images. By doing so, global and local characteristics of original images can be utilized for hiding more capacity with acceptable quality of output image. With our method, better performances can be obtained with enhanced image quality, the more embedding capacity, and comparable amount of side information for decoding. More importantly, the reversibility of our method is guaranteed, meaning that original image and hidden message can both be perfectly recovered at the decoder. Simulation results demonstrate that proposed method in this paper outperforms those in conventional algorithms. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
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36. Comparative performance of alternative humanitarian logistic structures after the Port-au-Prince earthquake: ACEs, PIEs, and CANs
- Author
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Holguín-Veras, José, Jaller, Miguel, and Wachtendorf, Tricia
- Subjects
- *
HAITI Earthquake, Haiti, 2010 , *DISASTER relief , *COMPARATIVE studies , *HUMANITARIAN assistance , *PERFORMANCE evaluation , *CRITICAL analysis - Abstract
Abstract: The paper analyzes the performance of different post-disaster humanitarian logistic structures that arose in response to the Port-au-Prince earthquake of January 12th, 2010. Based on field work conducted by the authors, the paper defines a typology of structures; assesses their relative performance in terms of delivering relief aid; and identifies the causes that explain the differences between them. Three structures are defined for comparative purposes: Agency Centric Efforts (ACEs), Partially Integrated Efforts (PIEs), and Collaborative Aid Networks (CANs). These structures differ to the extent to which they are integrated with the local social networks during the relief effort. Representative examples were analyzed to illustrate their inherent strengths and weaknesses, and reach conclusions of general applicability. The authors strengthen the analyses with discussions of “comparables,” i.e., other cases not fully discussed in the paper that shed additional light onto the performance of the structures. The paper’s analyses are based on dozens of interviews, both formal and informal, conducted with individuals directly involved in the relief effort, complemented with critical analyses of news accounts, and reports produced by the agencies involved. Based on its chief findings, the paper makes policy recommendations to maximize the effectiveness of future relief distribution efforts in response to disasters of various sizes. [Copyright &y& Elsevier]
- Published
- 2012
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37. A novel data association scheme for LEO space debris surveillance based on a double fence radar system
- Author
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Huang, Jian, Hu, Weidong, Xin, Qin, and Guo, Weiwei
- Subjects
- *
SPACE debris , *LOW earth orbit satellites , *SURVEILLANCE radar , *COMPARATIVE studies , *PERFORMANCE evaluation , *IRIDIUM , *SPACE environment - Abstract
Abstract: The increasing amount of space debris threatens to seriously deteriorate and damage space-based instruments in Low Earth Orbit (LEO) environments. Therefore, LEO space debris surveillance systems must be developed to provide situational awareness in space and issue warnings of collisions with LEO space debris. In this paper, a double fence radar system is proposed as an emerging paradigm for LEO space debris surveillance. This system exhibits several unique and promising characteristics compared with existing surveillance systems. In this paper, we also investigate the data association scheme for LEO space debris surveillance based on a double fence radar system. We also perform a theoretical analysis of the performance of our proposed scheme. The superiority and the effectiveness of our novel data association scheme is demonstrated by experimental results. The data used in our experiments is the LEO space debris catalog produced by the North American Air Defense Command (NORAD) up to 2009, especially for scenarios with high densities of LEO space debris, which were primarily produced by the collisions between Iridium 33 and Cosmos 2251. We hope that our work will stimulate and benefit future work on LEO space debris surveillance approaches and enable construction of the double fence radar system. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
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38. Voice activity detection algorithm using nonlinear spectral weights, hangover and hangbefore criteria
- Author
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Vlaj, Damjan, Kačič, Zdravko, and Kos, Marko
- Subjects
- *
ALGORITHMS , *AUTOMATIC speech recognition , *NONLINEAR systems , *RADIO frequency , *GAUSSIAN mixture models , *COMPARATIVE studies , *PERFORMANCE evaluation , *COMPUTER simulation - Abstract
Abstract: This paper introduces a nonlinear function into the frequency spectrum that improves the detection of vowels, diphthongs, and semivowels within the speech signal. The lower efficiency of consonant detection was solved by implementing the hangover and hangbefore criteria. This paper presents a procedure for faster definition of those optimal constants used by hangover and hangbefore criteria. A nonlinearly changed frequency spectrum is used in the proposed GMM (Gaussian Mixture Model) based VAD (Voice Activity Detection) algorithm. Comparative tests between the proposed VAD algorithm and seven other VAD algorithms were made on the Aurora 2 database. The experiments were based on frame error detection and on speech recognition performance for two types of acoustic training modes (multi-condition and clean only). The lowest average percentage of frame errors was obtained by the proposed VAD algorithm, which also achieved positive improvement in the speech recognition performance for both types of acoustic training modes. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
39. Performance analysis of under-modelling stereophonic acoustic echo cancellation by adaptive filtering LMS algorithm
- Author
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Djendi, Mohamed and Bounif, Aouda
- Subjects
- *
ADAPTIVE filters , *ECHO suppression , *PERFORMANCE evaluation , *MEAN square algorithms , *SYSTEM identification , *STATISTICS , *COMPUTER simulation , *COMPARATIVE studies - Abstract
Abstract: This paper addresses the field of stereophonic acoustic echo cancellation (SAEC) with adaptive filtering algorithms. In SAEC applications, using the least mean square (LMS) algorithm, it is usually assumed that the lengths of the adaptive filters are equal to that of the unidentified system responses. Although, in many realistic situations, under-modelled lengths adaptive filters, whose lengths are less than that of the unidentified systems (under-modelled systems), are employed, and analysis results for the exact modelled stereophonic LMS algorithm are not automatically appropriate to the under-modeled lengths. In this paper, we present a statistical analysis of the under-modeled stereophonic LMS algorithm. Exact expressions and deterministic recursive equations to the mean coefficients behavior of the adaptive LMS filters are derived to completely characterize and assess the performances (transient and steady-state) of the under-modeling stereophonic LMS algorithm. The expected theoretical behaviour is compared with Monte Carlo simulations and practical experimental results, showing a very good agreement. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
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40. Optimal planning and design of a renewable energy based supply system for microgrids
- Author
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Hafez, Omar and Bhattacharya, Kankar
- Subjects
- *
OPTIMAL designs (Statistics) , *RENEWABLE energy sources , *POLLUTION , *GRID computing , *PERFORMANCE evaluation , *ENERGY conservation , *ELECTRONIC systems , *COMPARATIVE studies - Abstract
Abstract: Renewable energy sources are gradually being recognized as important options in supply side planning for microgrids. This paper focuses on the optimal design, planning, sizing and operation of a hybrid, renewable energy based microgrid with the goal of minimizing the lifecycle cost, while taking into account environmental emissions. Four different cases including a diesel-only, a fully renewable-based, a diesel-renewable mixed, and an external grid-connected microgrid configurations are designed, to compare and evaluate their economics, operational performance and environmental emissions. Analysis is also carried out to determine the break-even economics for a grid-connected microgrid. The well-known energy modeling software for hybrid renewable energy systems, HOMER is used in the studies reported in this paper. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
41. Transforming geocentric cartesian coordinates to geodetic coordinates by using differential search algorithm
- Author
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Civicioglu, Pinar
- Subjects
- *
SEARCH algorithms , *PROBLEM solving , *GEODESY , *DIFFERENTIAL geometry , *COMPARATIVE studies , *COMPUTER algorithms , *PERFORMANCE evaluation , *COORDINATES - Abstract
Abstract: In order to solve numerous practical navigational, geodetic and astro-geodetic problems, it is necessary to transform geocentric cartesian coordinates into geodetic coordinates or vice versa. It is very easy to solve the problem of transforming geodetic coordinates into geocentric cartesian coordinates. On the other hand, it is rather difficult to solve the problem of transforming geocentric cartesian coordinates into geodetic coordinates as it is very hard to define a mathematical relationship between the geodetic latitude (φ) and the geocentric cartesian coordinates (X, Y, Z). In this paper, a new algorithm, the Differential Search Algorithm (DS), is presented to solve the problem of transforming the geocentric cartesian coordinates into geodetic coordinates and its performance is compared with the performances of the classical methods (i.e., ) and Computational-Intelligence algorithms (i.e., ABC, JDE, JADE, SADE, EPSDE, GSA, PSO2011, and CMA–ES). The statistical tests realized for the comparison of performances indicate that the problem-solving success of DS algorithm in transforming the geocentric cartesian coordinates into geodetic coordinates is higher than those of all classical methods and Computational-Intelligence algorithms used in this paper. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
42. Profiling instances in noise reduction
- Author
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Delany, Sarah Jane, Segata, Nicola, and Mac Namee, Brian
- Subjects
- *
MACHINE learning , *NOISE control , *COMPARATIVE studies , *PERFORMANCE evaluation , *EMPIRICAL research , *COMPUTER algorithms , *COMPUTER simulation , *DATA analysis - Abstract
Abstract: The dependency on the quality of the training data has led to significant work in noise reduction for instance-based learning algorithms. This paper presents an empirical evaluation of current noise reduction techniques, not just from the perspective of their comparative performance, but from the perspective of investigating the types of instances that they focus on for removal. A novel instance profiling technique known as RDCL profiling allows the structure of a training set to be analysed at the instance level categorising each instance based on modelling their local competence properties. This profiling approach offers the opportunity of investigating the types of instances removed by the noise reduction techniques that are currently in use in instance-based learning. The paper also considers the effect of removing instances with specific profiles from a dataset and shows that a very simple approach of removing instances that are misclassified by the training set and cause other instances in the dataset to be misclassified is an effective noise reduction technique. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
43. Algorithms for morphological profile filters and their comparison
- Author
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Lou, Shan, Jiang, Xiangqian, and Scott, Paul J.
- Subjects
- *
FILTERS (Mathematics) , *MATHEMATICAL morphology , *ALGORITHMS , *COMPARATIVE studies , *SURFACES (Technology) , *TRIANGULATION , *PERFORMANCE evaluation - Abstract
Abstract: Morphological filters, regarded as the complement of mean-line based filters, are useful in the analysis of surface texture and the prediction of functional performance. The paper first recalls two existing algorithms, the naive algorithm and the motif combination algorithm, originally developed for the traditional envelope filter. With minor extension, they could be used to compute morphological filters. A recent novel approach based on the relationship between the alpha shape and morphological closing and opening operations is presented as well. Afterwards two novel algorithms are developed. By correlating the convex hull and morphological operations, the Graham scan algorithm, original developed for the convex hull is modified to compute the morphological envelopes. The alpha shape method depending on the Delaunay triangulation is costly and redundant for the computation for the alpha shape for a given radius. A recursive algorithm is proposed to solve this problem. A series of observations are presented for searching the contact points. Based on the proposed observations, the algorithm partitions the profile data into small segments and searches the contact points in a recursive manner. The paper proceeds to compare the five distinct algorithms in five aspects: algorithm verification, algorithm analysis, performance evaluation, end effects correction, and areal extension. By looking into these aspects, the merits and shortcomings of these algorithms are evaluated and compared. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
44. Comparison of LMS-TEQ and DF-TEQ to reduce cyclic prefix length in direct detection optical OFDM system
- Author
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Ghanbarisabagh, Mohammad, Alias, M.Y., and Abdul-Rashid, H.A.
- Subjects
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EQUALIZERS (Electronics) , *COMPARATIVE studies , *TIME-domain analysis , *LEAST squares , *ORTHOGONAL frequency division multiplexing , *SINGLE-mode optical fibers , *MATHEMATICAL models , *OPTICAL detectors , *PERFORMANCE evaluation - Abstract
Abstract: This paper presents the comparison of using least mean square time-domain equalizer (LMS-TEQ) and decision feedback time-domain equalizer (DF-TEQ) to reduce cyclic prefix (CP) length for direct-detection of optical orthogonal frequency division multiplexing (O-OFDM) over 6960km of single mode fiber (SMF). Both TEQs are used immediately after the channel. Numerical modeling results show that they can cancel the residual inter symbol interference (ISI) and inter carrier interference (ICI) caused by both the group velocity dispersion (GVD) and the CP length being shorter than the channel impulse response (CIR). Using these TEQs allow the reduction of CP length, and consequently leading to system performance improvement. On the other hand, each of TEQs adds complexity to the system. Therefore, the aim of this paper is to analyze and compare the performance of LMS-TEQ and DF-TEQ while considering different CP length and complexity. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
45. CRM: An efficient trust and reputation model for agent computing
- Author
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Khosravifar, Babak, Bentahar, Jamal, Gomrokchi, Maziar, and Alam, Rafiul
- Subjects
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MULTIAGENT systems , *INFORMATION sharing , *PERFORMANCE evaluation , *DISTRIBUTED computing , *INTELLIGENT agents , *ESTIMATION theory , *COMPARATIVE studies , *MATHEMATICAL models - Abstract
Abstract: In open multi-agent systems, agents engage in interactions to share and exchange information. Due to the fact that these agents are self-interested, they may jeopardize mutual trust by not performing actions as they are expected to do. To this end, different models of trust have been proposed to assess the credibility of peers in the environment. These frameworks fail to consider and analyze the multiple factors impacting the trust. In this paper, we overcome this limit by proposing a comprehensive trust framework as a multi-factor model, which applies a number of measurements to evaluate the trust of interacting agents. First, this framework considers direct interactions among agents, and this part of the framework is called online trust estimation. Furthermore, after a variable interval of time, the actual performance of the evaluated agent is compared against the information provided by some other agents (consulting agents). This comparison in the off-line process leads to both adjusting the credibility of the contributing agents in trust evaluation and improving the system trust evaluation by minimizing the estimation error. What specifically distinguishes this work from the previous proposals in the same domain is its novelty in after-interaction investigation and performance analysis that prove the applicability of the proposed model in distributed multi-agent systems. In this paper, the agent structure and interaction mechanism of the proposed framework are described. A theoretical analysis of trust assessment and the system implementation along with simulations are also discussed. Finally, a comparison of our trust framework with other well-known frameworks from the literature is provided. [Copyright &y& Elsevier]
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- 2012
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46. Survey and performance evaluation on some automotive semi-active suspension control methods: A comparative study on a single-corner model
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Poussot-Vassal, C., Spelta, C., Sename, O., Savaresi, S.M., and Dugard, L.
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PERFORMANCE evaluation , *AUTOMOTIVE engineering , *AUTOMOBILE springs & suspension , *COMPARATIVE studies , *MATHEMATICAL models , *CONTROL theory (Engineering) , *CONJOINT analysis - Abstract
Abstract: In this paper, an overview and a benchmark of some semi-active suspension control strategy performances is proposed. Based on a recent result of the authors, where the optimal semi-active performance trade-off was addressed, here a complete benchmark to evaluate any controlled semi-active suspension is proposed, and applied to different control approaches. This paper aims at providing a picture – as complete as possible – of the present state of the art in the semi-active suspension control field in terms of comfort and road-holding performance evaluation and trade-off. [Copyright &y& Elsevier]
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- 2012
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47. Spatial content-based scene similarity assessment
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Wang, Caixia, Stefanidis, Anthony, and Agouris, Peggy
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ALGORITHMS , *ACQUISITION of data , *MATCHING theory , *GRAPH theory , *STRUCTURAL frames , *PERFORMANCE evaluation , *COMPARATIVE studies - Abstract
Abstract: Scene comparison and matching is a fundamental operation in geoinformatics. However, existing solutions are rather inadequate to support scene similarity assessment when comparing datasets collected from diverse sources especially ones that are available in diverse modalities (e.g. comparing image to vector datasets), or represent different time instances and thus differ partially in their content. In this paper we introduce a two-stage scene similarity assessment and matching framework that makes use of spatial scene content to compare and match two scenes as they may be captured in two different datasets (e.g. an aerial image and a map). At first stage our approach makes use of a matching algorithm based on the comparison of attributed graphs, where linear feature networks (e.g. road networks) are transformed into graphs and network properties are expressed through graph-embedded invariant attributes. By matching these graphs we can assess the similarity between two scenes. At the second stage, we proceed with an invariant scene comparison metric that incorporates additional scene content in the form of object configurations present within individual road network loops (e.g. building arrangements within city squares). By combining diverse but co-located pieces of information (e.g. roads and buildings) in an integrated process, our algorithm supports scene comparison and matching even when comparing heterogeneous datasets. In this paper we present key theoretical concepts and provide experimental results to demonstrate the performance of the proposed approach. [Copyright &y& Elsevier]
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- 2012
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48. A comparative study on financial positions of shipping companies in Taiwan and Korea using entropy and grey relation analysis
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Lee, Paul Tae-Woo, Lin, Cheng-Wei, and Shin, Sung-Ho
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COMPARATIVE studies , *SHIPPING companies , *ENTROPY (Information theory) , *GREY relational analysis , *INTERNATIONAL trade , *CRISES , *PERFORMANCE evaluation , *ECONOMIC impact - Abstract
Abstract: The international trade of Korea and Taiwan has been heavily dependent upon international seatransportation owing to geo-political aspects. Therefore, the two countries have exerted to develop and promote ocean-going shipping industry in order to support their economies. Recent financial crisis in together with the economic slowdown has reduced seaborne trade cargoes, which resulted in remarkably deteriorated revenues of the container shipping sector. Major container shipping companies of both countries such as Evergreen, Yang Ming, Hyundai, and Hanjin under our study are no exception. This paper intends to achieve two-fold aims. The first applies entropy to find the relative weights of financial ratios of the four companies each year. In so doing, we can find the weights variance for the period of 1999–2009 based on the financial performance of the above companies. The second is to rank the companies in the period by grey relation analysis. On the basis of findings in this paper, we suggest business policy implications to mitigate impacts of the financial tsunami in the context of world shipping area. [Copyright &y& Elsevier]
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- 2012
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49. Using a Product Manifold distance for unsupervised action recognition
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O'Hara, Stephen, Lui, Yui Man, and Draper, Bruce A.
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HUMAN activity recognition , *COMPARATIVE studies , *VIDEO excerpts , *FACIAL expression , *SILHOUETTES , *CLUSTER analysis (Statistics) , *PERFORMANCE evaluation , *MANIFOLDS (Mathematics) , *DATABASES - Abstract
Abstract: This paper presents a method for unsupervised learning and recognition of human actions in video. Lacking any supervision, there is nothing except the inherent biases of a given representation to guide grouping of video clips along semantically meaningful partitions. Thus, in the first part of this paper, we compare two contemporary methods, Bag of Features (BOF) and Product Manifolds (PM), for clustering video clips of human facial expressions, hand gestures, and full-body actions, with the goal of better understanding how well these very different approaches to behavior recognition produce semantically relevant clustering of data. We show that PM yields superior results when measuring the alignment between the generated clusters and the nominal class labeling of the data set. We found that while gross motions were easily clustered by both methods, the lack of preservation of structural information inherent to the BOF representation leads to limitations that are not easily overcome without supervised training. This was evidenced by the poor separation of shape labels in the hand gestures data by BOF, and the overall poor performance on full-body actions. In the second part of this paper, we present an unsupervised mechanism for learning micro-actions in continuous video streams using the PM representation. Unlike other works, our method requires no prior knowledge of an expected number of labels/classes, requires no silhouette extraction, is tolerant to minor tracking errors and jitter, and can operate at near real-time speed. We show how to construct a set of training “tracklets,” how to cluster them using the Product Manifold distance measure, and how to perform detection using exemplars learned from the clusters. Further, we show that the system is amenable to incremental learning as anomalous activities are detected in the video stream. We demonstrate performance using the publicly-available ETHZ Livingroom data set. [Copyright &y& Elsevier]
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- 2012
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50. Performance evaluation of a 3-D kinetic model for CANDU reactors in a closed-loop environment
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Xia, Lingzhi, Jiang, Jin, Javidnia, Hooman, and Luxat, John C.
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CANDU reactors , *PERFORMANCE evaluation , *CLOSED loop systems , *NEUTRON flux , *SIMULATION methods & models , *COMPARATIVE studies - Abstract
Abstract: The performance of a newly developed three dimensional (3-D) reactor kinetic model for CANDU reactor is evaluated in this paper. The evaluation is carried out in a closed-loop environment with the help of an existing reactor regulating system (RRS). The 3-D model is obtained based on a modal synthesis method, which represents the neutron flux distribution inside the reactor in both time and space. Throughout this paper, a special attention has been paid to compare the performance of the developed 3-D model with that of traditional coupled point kinetic models. The dynamic behavior of the reactor model in a practical load-following mode has also been examined. The accuracy of the model has been validated against actual plant measurements under both transient and steady-state conditions. Through the analysis and the simulation studies, it has convincingly demonstrated that the developed 3-D model has significant advantages over traditional coupled point kinetic models in terms of the improved accuracy and the higher resolution in modeling the reactor internal dynamics. [Copyright &y& Elsevier]
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- 2012
- Full Text
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