The Experts below are selected from a list of 61053 Experts worldwide ranked by ideXlab platform

Bogdan Piwakowski - One of the best experts on this subject based on the ideXlab platform.

  • accuracy of parameter identification using the dispersion of surface waves and the role of data quality for inhomogeneous concrete
    Ndt & E International, 2018
    Co-Authors: Radoslaw Drelich, Mariusz Kaczmarek, Bogdan Piwakowski
    Abstract:

    Abstract We study the influence of the data quality on the accuracy of parameter identification for inhomogeneous concrete. The surface of the concrete may differ as a result of either intentional action (decoration or repair) or the interaction of initially homogeneous concrete with the environment. Non-destructive evaluation of the concrete surface layer is vital to monitoring the integrity of concrete structures and preventing their irreversible damage. We use the methodology (also used for ground structure recovery) of multichannel analysis of surface waves as the non-destructive testing (NDT) tool in the civil engineering domain to characterize the concrete surface layer. The procedure consists of the generation and reception of surface waves within the required frequency band. Then, the phase velocity dispersion characteristic is extracted and used as input data for solving the inverse problem to obtain the variation of the shear wave velocity as a function of the sample depth. Two aspects of data quality are considered: completeness in the frequency or wavelength domain and accuracy. In the former case, the efficiency of identification is studied for variable ranges (in the frequency or wavelength domains) of the dispersion curve of the fundamental mode of the surface wave. The role of data accuracy is evaluated through comparison of the identified parameters using experimental and appropriate synthetic data. To perform these studies, cuboidal models of inhomogeneous concrete composed of two layers of different classes of concrete are prepared. During experiments, surface wave signals are acquired within a frequency range of 35 kHz–160 kHz using a non-contact ultrasonic automated scanner, which enables quick and precise signal recording, avoiding concrete surface modification through the use of the coupling agent. Experimental dispersion curves are obtained using the Slant-Stack transformation. The synthetic data are obtained from the solution of the Thomson-Haskell model. The inversions are performed using the in-house Software Cloud and tested and validated on the multilayer model samples. The criteria for the optimum wavelength intervals of the dispersion curves are proposed: the lower wavelength limit λ L  ≤ d, and the upper wavelength limit λ U  ≥ 3.5d, where d is the thickness of the top layer. The consequences of narrowing the intervals are thoroughly studied, and upper and lower limits are determined both for experimental and synthetic data. It is shown that the efficiency of inversion depends on both wavelength limits and accuracy of the data.

  • Accuracy of parameter identification using the dispersion of surface waves and the role of data quality for inhomogeneous concrete
    NDT & E International, 2018
    Co-Authors: Radoslaw Drelich, Mariusz Kaczmarek, Bogdan Piwakowski
    Abstract:

    We study the influence of the data quality on the accuracy of parameter identification for inhomogeneous concrete. The surface of the concrete may differ as a result of either intentional action (decoration or repair) or the interaction of initially homogeneous concrete with the environment. Non-destructive evaluation of the concrete surface layer is vital to monitoring the integrity of concrete structures and preventing their irreversible damage. We use the methodology (also used for ground structure recovery) of multichannel analysis of surface waves as the non-destructive testing (NDT) tool in the civil engineering domain to characterize the concrete surface layer. The procedure consists of the generation and reception of surface waves within the required frequency band. Then, the phase velocity dispersion characteristic is extracted and used as input data for solving the inverse problem to obtain the variation of the shear wave velocity as a function of the sample depth. Two aspects of data quality are considered: completeness in the frequency or wavelength domain and accuracy. In the former case, the efficiency of identification is studied for variable ranges (in the frequency or wavelength domains) of the dispersion curve of the fundamental mode of the surface wave. The role of data accuracy is evaluated through comparison of the identified parameters using experimental and appropriate synthetic data. To perform these studies, cuboidal models of inhomogeneous concrete composed of two layers of different classes of concrete are prepared. During experiments, surface wave signals are acquired within a frequency range of 35 kHz-160 kHz using a non-contact ultrasonic automated scanner, which enables quick and precise signal recording, avoiding concrete surface modification through the use of the coupling agent. Experimental dispersion curves are obtained using the Slant-Stack transformation. The synthetic data are obtained from the solution of the Thomson-Haskell model. The inversions are performed using the in-house Software Cloud and tested and validated on the multilayer model samples. The criteria for the optimum wavelength intervals of the dispersion curves are proposed: the lower wavelength limit lambda(L) = 3.5 d, where d is the thickness of the top layer. The consequences of narrowing the intervals are thoroughly studied, and upper and lower limits are determined both for experimental and synthetic data. It is shown that the efficiency of inversion depends on both wavelength limits and accuracy of the data.

Elisa Bertino - One of the best experts on this subject based on the ideXlab platform.

  • improving scalability of Software Cloud for composite web services
    International Conference on Cloud Computing, 2009
    Co-Authors: Qianhui Liang, Elisa Bertino
    Abstract:

    Most of the work on Cloud scalability has focused on the granularity of applications and systems deployed on the Cloud and on how to adjust their resource assignment according to the scale or volume of the requests. In this paper, we present a scheme for improving the scalability of service-based applications in a Cloud from the granularity of the constituent services and their individual placement in the Cloud. The approach we take is to analyze the communication patterns among the service operations of service-based applications and to analyze the assignment of the involved services to the available servers. We define a notion of scalability for service-based applications in a Cloud and a framework to measure the scalability. We then propose an optimized assignment strategy to improve the scalability of composite Web services in terms of the productivity of such services. We report preliminary simulation experimental results that show the effectiveness of our scheme.

  • IEEE Cloud - Improving Scalability of Software Cloud for Composite Web Services
    2009 IEEE International Conference on Cloud Computing, 2009
    Co-Authors: Qianhui Liang, Elisa Bertino
    Abstract:

    Most of the work on Cloud scalability has focused on the granularity of applications and systems deployed on the Cloud and on how to adjust their resource assignment according to the scale or volume of the requests. In this paper, we present a scheme for improving the scalability of service-based applications in a Cloud from the granularity of the constituent services and their individual placement in the Cloud. The approach we take is to analyze the communication patterns among the service operations of service-based applications and to analyze the assignment of the involved services to the available servers. We define a notion of scalability for service-based applications in a Cloud and a framework to measure the scalability. We then propose an optimized assignment strategy to improve the scalability of composite Web services in terms of the productivity of such services. We report preliminary simulation experimental results that show the effectiveness of our scheme.

Wu Chou - One of the best experts on this subject based on the ideXlab platform.

  • SaaS integration for Software Cloud
    Proceedings - 2010 IEEE 3rd International Conference on Cloud Computing, CLOUD 2010, 2010
    Co-Authors: Feng Liu, Wenzhong Guo, Zhi-qiang Zhao, Wu Chou
    Abstract:

    Software as a Service (SaaS) has been adopted in a fast pace for applications and services on Software Clouds. However, the success of SaaS in Software Cloud cannot obscure the integration challenges faced by developers and enterprise infrastructure IT. Among those challenges, firewall/NAT traversal and security issues often pose a serious bottleneck as enterprises may not be entirely comfortable running mission critical applications outside the corporate firewall. On the other hand, SaaS applications in the Cloud need to access enterprise on-premise applications for data exchange and on-premises services. The current approaches through opening special pin-holes on firewall or using dedicated VPNs have encountered a number of limitations and drawbacks. This paper presents a Proxy-based firewall/NAT traversal solution for SaaS integration (PASS). It allows SaaS applications to integrate with on-premise applications without firewall reconfiguration, while maintaining the security of on-premise applications. In addition, this approach is platform and application independent, making the SaaS integration seamless. Moreover, PASS is consistent with the enterprise web browsing infrastructure, and it requires little or no change to enterprise firewall/NAT configurations. In this paper we present the architecture of PASS and address SaaS integration challenges in Software Cloud, such as security/firewall, performance, and scalability. Experimental study based on our implemented system shows that the proposed approach of PASS is promising to resolve firewall/NAT traversal for SaaS integration with on-premise services.

  • IEEE Cloud - SaaS Integration for Software Cloud
    2010 IEEE 3rd International Conference on Cloud Computing, 2010
    Co-Authors: Feng Liu, Zhi-qiang Zhao, Weiping Guo, Wu Chou
    Abstract:

    Software as a Service (SaaS) has been adopted in a fast pace for applications and services on Software Clouds. However, the success of SaaS in Software Cloud cannot obscure the integration challenges faced by developers and enterprise infrastructure IT. Among those challenges, firewall/NAT traversal and security issues often pose a serious bottleneck as enterprises may not be entirely comfortable running mission critical applications outside the corporate firewall. On the other hand, SaaS applications in the Cloud need to access enterprise on-premise applications for data exchange and on-premises services. The current approaches through opening special pin-holes on firewall or using dedicated VPNs have encountered a number of limitations and drawbacks. This paper presents a Proxy-based firewall/NAT traversal solution for SaaS integration (PASS). It allows SaaS applications to integrate with on-premise applications without firewall reconfiguration, while maintaining the security of on-premise applications. In addition, this approach is platform and application independent, making the SaaS integration seamless. Moreover, PASS is consistent with the enterprise web browsing infrastructure, and it requires little or no change to enterprise firewall/NAT configurations. In this paper we present the architecture of PASS and address SaaS integration challenges in Software Cloud, such as security/firewall, performance, and scalability. Experimental study based on our implemented system shows that the proposed approach of PASS is promising to resolve firewall/NAT traversal for SaaS integration with on-premise services.

Radoslaw Drelich - One of the best experts on this subject based on the ideXlab platform.

  • accuracy of parameter identification using the dispersion of surface waves and the role of data quality for inhomogeneous concrete
    Ndt & E International, 2018
    Co-Authors: Radoslaw Drelich, Mariusz Kaczmarek, Bogdan Piwakowski
    Abstract:

    Abstract We study the influence of the data quality on the accuracy of parameter identification for inhomogeneous concrete. The surface of the concrete may differ as a result of either intentional action (decoration or repair) or the interaction of initially homogeneous concrete with the environment. Non-destructive evaluation of the concrete surface layer is vital to monitoring the integrity of concrete structures and preventing their irreversible damage. We use the methodology (also used for ground structure recovery) of multichannel analysis of surface waves as the non-destructive testing (NDT) tool in the civil engineering domain to characterize the concrete surface layer. The procedure consists of the generation and reception of surface waves within the required frequency band. Then, the phase velocity dispersion characteristic is extracted and used as input data for solving the inverse problem to obtain the variation of the shear wave velocity as a function of the sample depth. Two aspects of data quality are considered: completeness in the frequency or wavelength domain and accuracy. In the former case, the efficiency of identification is studied for variable ranges (in the frequency or wavelength domains) of the dispersion curve of the fundamental mode of the surface wave. The role of data accuracy is evaluated through comparison of the identified parameters using experimental and appropriate synthetic data. To perform these studies, cuboidal models of inhomogeneous concrete composed of two layers of different classes of concrete are prepared. During experiments, surface wave signals are acquired within a frequency range of 35 kHz–160 kHz using a non-contact ultrasonic automated scanner, which enables quick and precise signal recording, avoiding concrete surface modification through the use of the coupling agent. Experimental dispersion curves are obtained using the Slant-Stack transformation. The synthetic data are obtained from the solution of the Thomson-Haskell model. The inversions are performed using the in-house Software Cloud and tested and validated on the multilayer model samples. The criteria for the optimum wavelength intervals of the dispersion curves are proposed: the lower wavelength limit λ L  ≤ d, and the upper wavelength limit λ U  ≥ 3.5d, where d is the thickness of the top layer. The consequences of narrowing the intervals are thoroughly studied, and upper and lower limits are determined both for experimental and synthetic data. It is shown that the efficiency of inversion depends on both wavelength limits and accuracy of the data.

  • Accuracy of parameter identification using the dispersion of surface waves and the role of data quality for inhomogeneous concrete
    NDT & E International, 2018
    Co-Authors: Radoslaw Drelich, Mariusz Kaczmarek, Bogdan Piwakowski
    Abstract:

    We study the influence of the data quality on the accuracy of parameter identification for inhomogeneous concrete. The surface of the concrete may differ as a result of either intentional action (decoration or repair) or the interaction of initially homogeneous concrete with the environment. Non-destructive evaluation of the concrete surface layer is vital to monitoring the integrity of concrete structures and preventing their irreversible damage. We use the methodology (also used for ground structure recovery) of multichannel analysis of surface waves as the non-destructive testing (NDT) tool in the civil engineering domain to characterize the concrete surface layer. The procedure consists of the generation and reception of surface waves within the required frequency band. Then, the phase velocity dispersion characteristic is extracted and used as input data for solving the inverse problem to obtain the variation of the shear wave velocity as a function of the sample depth. Two aspects of data quality are considered: completeness in the frequency or wavelength domain and accuracy. In the former case, the efficiency of identification is studied for variable ranges (in the frequency or wavelength domains) of the dispersion curve of the fundamental mode of the surface wave. The role of data accuracy is evaluated through comparison of the identified parameters using experimental and appropriate synthetic data. To perform these studies, cuboidal models of inhomogeneous concrete composed of two layers of different classes of concrete are prepared. During experiments, surface wave signals are acquired within a frequency range of 35 kHz-160 kHz using a non-contact ultrasonic automated scanner, which enables quick and precise signal recording, avoiding concrete surface modification through the use of the coupling agent. Experimental dispersion curves are obtained using the Slant-Stack transformation. The synthetic data are obtained from the solution of the Thomson-Haskell model. The inversions are performed using the in-house Software Cloud and tested and validated on the multilayer model samples. The criteria for the optimum wavelength intervals of the dispersion curves are proposed: the lower wavelength limit lambda(L) = 3.5 d, where d is the thickness of the top layer. The consequences of narrowing the intervals are thoroughly studied, and upper and lower limits are determined both for experimental and synthetic data. It is shown that the efficiency of inversion depends on both wavelength limits and accuracy of the data.

Qianhui Liang - One of the best experts on this subject based on the ideXlab platform.

  • improving scalability of Software Cloud for composite web services
    International Conference on Cloud Computing, 2009
    Co-Authors: Qianhui Liang, Elisa Bertino
    Abstract:

    Most of the work on Cloud scalability has focused on the granularity of applications and systems deployed on the Cloud and on how to adjust their resource assignment according to the scale or volume of the requests. In this paper, we present a scheme for improving the scalability of service-based applications in a Cloud from the granularity of the constituent services and their individual placement in the Cloud. The approach we take is to analyze the communication patterns among the service operations of service-based applications and to analyze the assignment of the involved services to the available servers. We define a notion of scalability for service-based applications in a Cloud and a framework to measure the scalability. We then propose an optimized assignment strategy to improve the scalability of composite Web services in terms of the productivity of such services. We report preliminary simulation experimental results that show the effectiveness of our scheme.

  • IEEE Cloud - Improving Scalability of Software Cloud for Composite Web Services
    2009 IEEE International Conference on Cloud Computing, 2009
    Co-Authors: Qianhui Liang, Elisa Bertino
    Abstract:

    Most of the work on Cloud scalability has focused on the granularity of applications and systems deployed on the Cloud and on how to adjust their resource assignment according to the scale or volume of the requests. In this paper, we present a scheme for improving the scalability of service-based applications in a Cloud from the granularity of the constituent services and their individual placement in the Cloud. The approach we take is to analyze the communication patterns among the service operations of service-based applications and to analyze the assignment of the involved services to the available servers. We define a notion of scalability for service-based applications in a Cloud and a framework to measure the scalability. We then propose an optimized assignment strategy to improve the scalability of composite Web services in terms of the productivity of such services. We report preliminary simulation experimental results that show the effectiveness of our scheme.