Robustness testing for safety-critical embedded software is still a challenge in its nascent stages. In this paper, we propose a practical methodology and implement an environment by employing model-based robustness t...Robustness testing for safety-critical embedded software is still a challenge in its nascent stages. In this paper, we propose a practical methodology and implement an environment by employing model-based robustness testing for embedded software systems. It is a system-level black-box testing approach in which the fault behaviors of embedded software is triggered with the aid of modelbased fault injection by the support of an executable model-driven hardware-in-loop （HIL） testing environment. The prototype implementation of the robustness testing environment based on the proposed approach is experimentally discussed and illustrated by industrial case studies based on several avionics-embedded software systems. The results show that our proposed and implemented robustness testing method and environment are effective to find more bugs, and reduce burdens of testing engineers to enhance efficiency of testing tasks, especially for testing complex embedded systems.展开更多
Unified modeling language （UML） is a powerful graphical modeling language with intuitional meaning. It provides various diagrams to depict system characteristics and complex environment from different viewpoints and...Unified modeling language （UML） is a powerful graphical modeling language with intuitional meaning. It provides various diagrams to depict system characteristics and complex environment from different viewpoints and different application layers. UML-based software development and modeling environments have been widely accepted in industry, including areas in which safety is an important issue such as spaceflight, defense, automobile, etc. To ensure and improve software quality becomes a main concern in the field. As one of the key techniques for software quality, software testing can effectively detect system faults. UML based software testing based is an important research direction in software engineering. The key to software testing is the generation of test cases. This dissertation studies an approach to generating test cases from UML statecharts.展开更多
In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging ...In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging due to the unaffordable cost and high complexity when testing a large number of antennas. To solve this problem, the over-the-air (OTA) test has been presented, in which probe selection is the key to reduce the number of channel emulators and probes. In this paper, a novel artificial bee colony (ABC) algorithm is introduced to enhance the efficiency and accuracy of probe selection procedure. A sectoring- based multi-probe anechoic chamber (MPAC) is built to evaluate the throughput performance of massive MIMO equipped in 5G BS. In addition, link level simulation is carried out to evaluate the proposal’s performance gain under the commercial network assumptions, where the average throughput of three velocity is given with different SNR region. The results suggest that OTA chamber and multi-probe wall are available not only for 5G BSs, but also for user equipments (UEs) with end-to-end communication.展开更多
The construction of the UHVAC test base of SGCC is an important component of the pilot project on UHVAC power transmission and transformation in China. This paper introduces the layout, technical requirements and main...The construction of the UHVAC test base of SGCC is an important component of the pilot project on UHVAC power transmission and transformation in China. This paper introduces the layout, technical requirements and main test functions of the UHVAC test base as well as difficulties during construction. It lays stress on the characterization of a 1 000-kV single-circuit test line, a 1 000-kV one-tower double-circuit test line, a full voltage test site for UHV equipment, a climate laboratory, a corona cage and a long-wave-front impulse voltage generator.展开更多
The function of the UHVDC test base of the State Grid Corporation of China (SGCC) is oriented to serve UHVDC power transmission and substation projects, especially power transmission from West China to East China, and...The function of the UHVDC test base of the State Grid Corporation of China (SGCC) is oriented to serve UHVDC power transmission and substation projects, especially power transmission from West China to East China, and to promote localization of UHVDC transmission and substation equipment. In essentials, this test base consists of UHVDC test transmission line, corona cage, outdoor test site, UHV test hall, pollution and environment laboratory, electromagnetic environment simulation test site, insulator laboratory, arrester laboratory and live equipment test field. This paper introduces the function and design idea of the test base, presents the main performance parameters of the above-mentioned test facilities, and summarizes the matters of concern when siting and planning.展开更多
The essay aims at revealing the washback effect of task-based communicative language test(TBCLT) in a vocational college, with the further purpose to work out some ways to promote positive washback effect and reform t...The essay aims at revealing the washback effect of task-based communicative language test(TBCLT) in a vocational college, with the further purpose to work out some ways to promote positive washback effect and reform the current tests hence to improve vocational learning.展开更多
The present study aims at revealing the washback effect of task-based communicative language test(TBCLT) in a vo cational college, with the further purpose to work out some ways to promote positive washback effect and...The present study aims at revealing the washback effect of task-based communicative language test(TBCLT) in a vo cational college, with the further purpose to work out some ways to promote positive washback effect and reform the current tests hence to improve vocational teaching.展开更多
Parallel key-insulation allows the use of multiple helper keys to protect private decryption keys during secret decryption key updates. This approach prevents decryption key leakage or exposure in insecure environment...Parallel key-insulation allows the use of multiple helper keys to protect private decryption keys during secret decryption key updates. This approach prevents decryption key leakage or exposure in insecure environment. We combined parallel key-insulated encryption (PKIE) with multiple helper keys and identity-based encryption with the equality test (IBE-ET) to obtain parallel key insulated ID-based public key encryption with outsourced equivalent test (PKI-IBPKE-ET). The scheme inherits the advantages of identity-based encryption (IBE), which simplifies certificate management for public key encryption. Furthermore, the parallel key-insulation with multiple helper mechanism was introduced in our scheme, which perfectly reduced the possibility of helper key exposure. Our scheme will enable the protection and periodic update of decryption keys in insecure environment. Our scheme achieves a weak indistinguishable identity chosen ciphertext (W-IND-ID-CCA) security in the random oracle model. Ultimately, it is observed that our scheme is feasible and practical through the experimental simulation and theoretical analysis.展开更多
Globally, traditional power systems are rapidly transforming towards the adoption of smart grid platforms. Substations which are at the center of the electric power transformation from the power plant are changing to ...Globally, traditional power systems are rapidly transforming towards the adoption of smart grid platforms. Substations which are at the center of the electric power transformation from the power plant are changing to IEC 61850 based digital substations. Therefore, within substation, there is a growing demand for the IEC 61850 based Intelligent Electronic Devices (IEDs). The operation of multiple manufacturers of IEDs in a single digital substation network increases the need for IEC 61850 communications specification conformance diagnosis to ensure interoperability for efficient data exchange between IEDs. The IEC 61850-10 presents test items for diagnosing communication specification conformance. There are many test tools available in the market today to test the compliance of the IEC 61850 communications specifications to the IED. In this paper, we propose a model-based diagnostic method for IED communication conformance testing. The proposed model-based software therefore uses the “drag and drop” technique to select the various IEC 61850 communication services (objects) required to design the test case in a user friendly Graphical User Interface (GUI). This makes the service conformance testing more flexible for test engineers and system integrators especially in situations that require test case modifications. Also, the proposed software tool makes it easy to understand the various IEC 61850 services using the friendly GUI.展开更多
In this paper,a novel component based framework of test system is presented for the new requirements of dynamic changes of test functions and reconfiguration of test resources.The complexity of dynamic reconfiguration...In this paper,a novel component based framework of test system is presented for the new requirements of dynamic changes of test functions and reconfiguration of test resources.The complexity of dynamic reconfiguration arises from the scale, redirection,extensibility and interconnection of components in test system.The paper is started by discussing the component assem- bly based framework which provide the open platform to the deploy of companents and then the script interpreter model is introduced to dynamically create the components and build the test system by analyzing XML based information of test system.A pipeline mod- el is presented to provide the data channels and behavior reflection among the components.Finally,a dynamic reconfigurable test system is implemented on the basis of COM and applied in the remote test and control system of CNC machine.展开更多
The tarnishing test in the presence of hydrogen sulfide（H2S） vapors has been used to investigate the tarnish resistance capability of copper-based alloys coated with Si02-like films by means of plasma-enhanced chemi...The tarnishing test in the presence of hydrogen sulfide（H2S） vapors has been used to investigate the tarnish resistance capability of copper-based alloys coated with Si02-like films by means of plasma-enhanced chemical vapor deposition（PECVD） fed with a tetraethoxysilane/oxygen mixture.The chemical and morphological properties of the films have been characterized by using infrared absorption spectroscopy（IR） and scanning electron microscopy（SEM）with energy disperse spectroscopy（EDS）.The corrosion products of the samples after the tarnishing test have been identified by X-ray diffraction analysis（XRD）.It has been found that SiO2-like films formed via PECVD with a high O2 flow rate could protect copper-based alloys from H2S vapor tarnishing.The alloys coated at the O2 flow rate of 20 sccm remain uncorroded after 54days of H2S vapor tarnish testing.The corrosion products for the alloys deposited at a low O2flow rate after 54 days of tarnish testing are mainly composed of brochantite.展开更多
Quality of software systems is highly demanded in today’s scenario. Highly testable system enhances the reliability also. More than 50% of test effort-time and cost are used to produce a highly testable system. Thus,...Quality of software systems is highly demanded in today’s scenario. Highly testable system enhances the reliability also. More than 50% of test effort-time and cost are used to produce a highly testable system. Thus, design-for-testability is needed to reduce the test effort. In order to enhance the quality, productivity and reduced cost of the software organizations are promoting to produce the reuse-oriented products. Incorporating reuse technology in both aspects-software development process and test process may payoff many folds. Keeping this view, our study focus the testability of the object-oriented framework based software systems and identify that flexibility at the variable points of the object-oriented framework, chosen for framework instantiation, greatly affects the testability of object-oriented framework based software at each level of testing. In the current paper, we propose a testability model considering the flexible aspect of the variable point to estimate testability in the early phase, requirement analysis phase, of development process of the framework based software. The proposed model helps to improve the testability of the software before the implementation starts thus reducing the overall development cost.展开更多
In a component-based software development life cycle, selection of preexisting components is an important task. Every component that has to be reused has an associated risk of failure of not meeting the functional and...In a component-based software development life cycle, selection of preexisting components is an important task. Every component that has to be reused has an associated risk of failure of not meeting the functional and non-functional requirements. A component's failure would lead a developer to look for some other alternative of combinations of COTS, in-house and engineered components among possible candidate combinations. This means design itself can readily change. The very process of design of a software system and component selection seems to be heavily dependent on testing results. Instability of design, further, becomes more severe due to requirements change requests. Therefore, this instability of design has to be essentially mitigated by using proper design and testing approaches, otherwise, it may lead to exorbitantly high testing cost due to the repeated testing of various alternatives. How these three activities: Component-based software design, component selection and component-based software testing are interrelated? What process model is most suited to address this concern? This work explores the above questions and their implication in terms of nature of a process model that can be convincing in case of component-based software development.展开更多
The performance of a well-designed layer of sand, and composites like layer of sand mixed with shredded rubber tire (RSM) as low cost base isolators, is studied in shake table tests in the laboratory. The building fou...The performance of a well-designed layer of sand, and composites like layer of sand mixed with shredded rubber tire (RSM) as low cost base isolators, is studied in shake table tests in the laboratory. The building foundation is modeled by a 200 mm by 200 mm and 40 mm thick rigid plexi-glass block. The block is placed in the middle of a 1m by 1m tank filled with sand. The selected base isolator is placed between the block and the sand foundation. Accelerometers are placed on top of the footing and foundation sand layer. The displacement of the footing is also measured by LVDT. The whole setup is mounted on a shake table and subjected to sinusoidal motions with varying amplitude and frequency. Sand is found to be effective only at very high amplitude (> 0.65 g) of motions. The performance of a composite consisting of sand and 50% shredded rubber tire placed under the footing is found to be most promising as a low-cost effective base isolator.展开更多
The corrosion resistance of the Al2O3-C based refractories in melts containing titania has been studied by quasi-station immersion and rotary immersion. The corrosionrate is decreased with the addition of graphite car...The corrosion resistance of the Al2O3-C based refractories in melts containing titania has been studied by quasi-station immersion and rotary immersion. The corrosionrate is decreased with the addition of graphite carbon, and ZrO2 in the refractories . The corrosion, mechanism of Al2O3-C refractories, is. the oxidization of graphite carbon by the oxides of the melts the formation of deteriorate layer, For the Al2O3-C-ZrO2 refractories, the corrosion behavior is due to the, interaction between melts and refractories . The new compounds of FeO. SiO2, SiZrO4, FeO. 3 CaO, 2CaO. SiO2 and CaO. SiO2 are formed in the deteriorate layer.展开更多
This paper proposes an autopilot system that can be used to control the small scale rotorcraft during the flight test for linear-frequency-domain system identification. The input frequency-sweep is generated automatic...This paper proposes an autopilot system that can be used to control the small scale rotorcraft during the flight test for linear-frequency-domain system identification. The input frequency-sweep is generated automatically as part of the autopilot control command. Therefore the bandwidth coverage and consistency of the frequency-sweep are guaranteed to produce high quality data for system identification. Beside that, we can set the safety parameters during the flight test （maximum roll/pitch value, minimum altitude, etc.） so the safety of the whole flight test is guaranteed. This autopilot system is validated using hardware in the loop simulator for hover flight condition.展开更多
This article extends a signal-based approach formerly proposed by the authors, which utilizes the fractal dimension of time frequency feature （FDTFF） of displacements, for earthquake damage detection of moment resis...This article extends a signal-based approach formerly proposed by the authors, which utilizes the fractal dimension of time frequency feature （FDTFF） of displacements, for earthquake damage detection of moment resist frame （MRF）, and validates the approach with shaking table tests. The time frequency feature （TFF） of the relative displacement at measured story is defined as the real part of the coefficients of the analytical wavelet transform. The fractal dimension （FD） is to quantify the TFF within the fundamental frequency band using box counting method. It is verified that the FDTFFs at all stories of the linear MRF are identical with the help of static condensation method and modal superposition principle, while the FDTFFs at the stories with localized nonlinearities due to damage will be different from those at the stories without nonlinearities using the reverse-path methodology. By comparing the FDTFFs of displacements at measured stories in a structure, the damage-induced nonlinearity of the structure under strong ground motion can be detected and localized. Finally shaking table experiments on a 1：8 scale sixteen-story three-bay steel MRF with added frictional dampers, which generate local nonlinearities, are conducted to validate the approach.展开更多
基金the Aeronautics Science Foundation of China(No.2011ZD51055)Science and Technology on Reliability&Environmental Engineering Laboratory(No.302367)the National Pre-Research Foundation of China(No.51319080201)
文摘Robustness testing for safety-critical embedded software is still a challenge in its nascent stages. In this paper, we propose a practical methodology and implement an environment by employing model-based robustness testing for embedded software systems. It is a system-level black-box testing approach in which the fault behaviors of embedded software is triggered with the aid of modelbased fault injection by the support of an executable model-driven hardware-in-loop （HIL） testing environment. The prototype implementation of the robustness testing environment based on the proposed approach is experimentally discussed and illustrated by industrial case studies based on several avionics-embedded software systems. The results show that our proposed and implemented robustness testing method and environment are effective to find more bugs, and reduce burdens of testing engineers to enhance efficiency of testing tasks, especially for testing complex embedded systems.
文摘Unified modeling language （UML） is a powerful graphical modeling language with intuitional meaning. It provides various diagrams to depict system characteristics and complex environment from different viewpoints and different application layers. UML-based software development and modeling environments have been widely accepted in industry, including areas in which safety is an important issue such as spaceflight, defense, automobile, etc. To ensure and improve software quality becomes a main concern in the field. As one of the key techniques for software quality, software testing can effectively detect system faults. UML based software testing based is an important research direction in software engineering. The key to software testing is the generation of test cases. This dissertation studies an approach to generating test cases from UML statecharts.
基金supported by the State Major Science and Technology Special Projects under Grant No. 2018ZX03001028-003
文摘In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging due to the unaffordable cost and high complexity when testing a large number of antennas. To solve this problem, the over-the-air (OTA) test has been presented, in which probe selection is the key to reduce the number of channel emulators and probes. In this paper, a novel artificial bee colony (ABC) algorithm is introduced to enhance the efficiency and accuracy of probe selection procedure. A sectoring- based multi-probe anechoic chamber (MPAC) is built to evaluate the throughput performance of massive MIMO equipped in 5G BS. In addition, link level simulation is carried out to evaluate the proposal’s performance gain under the commercial network assumptions, where the average throughput of three velocity is given with different SNR region. The results suggest that OTA chamber and multi-probe wall are available not only for 5G BSs, but also for user equipments (UEs) with end-to-end communication.
文摘The construction of the UHVAC test base of SGCC is an important component of the pilot project on UHVAC power transmission and transformation in China. This paper introduces the layout, technical requirements and main test functions of the UHVAC test base as well as difficulties during construction. It lays stress on the characterization of a 1 000-kV single-circuit test line, a 1 000-kV one-tower double-circuit test line, a full voltage test site for UHV equipment, a climate laboratory, a corona cage and a long-wave-front impulse voltage generator.
文摘The function of the UHVDC test base of the State Grid Corporation of China (SGCC) is oriented to serve UHVDC power transmission and substation projects, especially power transmission from West China to East China, and to promote localization of UHVDC transmission and substation equipment. In essentials, this test base consists of UHVDC test transmission line, corona cage, outdoor test site, UHV test hall, pollution and environment laboratory, electromagnetic environment simulation test site, insulator laboratory, arrester laboratory and live equipment test field. This paper introduces the function and design idea of the test base, presents the main performance parameters of the above-mentioned test facilities, and summarizes the matters of concern when siting and planning.
文摘The essay aims at revealing the washback effect of task-based communicative language test(TBCLT) in a vocational college, with the further purpose to work out some ways to promote positive washback effect and reform the current tests hence to improve vocational learning.
文摘The present study aims at revealing the washback effect of task-based communicative language test(TBCLT) in a vo cational college, with the further purpose to work out some ways to promote positive washback effect and reform the current tests hence to improve vocational teaching.
文摘Parallel key-insulation allows the use of multiple helper keys to protect private decryption keys during secret decryption key updates. This approach prevents decryption key leakage or exposure in insecure environment. We combined parallel key-insulated encryption (PKIE) with multiple helper keys and identity-based encryption with the equality test (IBE-ET) to obtain parallel key insulated ID-based public key encryption with outsourced equivalent test (PKI-IBPKE-ET). The scheme inherits the advantages of identity-based encryption (IBE), which simplifies certificate management for public key encryption. Furthermore, the parallel key-insulation with multiple helper mechanism was introduced in our scheme, which perfectly reduced the possibility of helper key exposure. Our scheme will enable the protection and periodic update of decryption keys in insecure environment. Our scheme achieves a weak indistinguishable identity chosen ciphertext (W-IND-ID-CCA) security in the random oracle model. Ultimately, it is observed that our scheme is feasible and practical through the experimental simulation and theoretical analysis.
文摘Globally, traditional power systems are rapidly transforming towards the adoption of smart grid platforms. Substations which are at the center of the electric power transformation from the power plant are changing to IEC 61850 based digital substations. Therefore, within substation, there is a growing demand for the IEC 61850 based Intelligent Electronic Devices (IEDs). The operation of multiple manufacturers of IEDs in a single digital substation network increases the need for IEC 61850 communications specification conformance diagnosis to ensure interoperability for efficient data exchange between IEDs. The IEC 61850-10 presents test items for diagnosing communication specification conformance. There are many test tools available in the market today to test the compliance of the IEC 61850 communications specifications to the IED. In this paper, we propose a model-based diagnostic method for IED communication conformance testing. The proposed model-based software therefore uses the “drag and drop” technique to select the various IEC 61850 communication services (objects) required to design the test case in a user friendly Graphical User Interface (GUI). This makes the service conformance testing more flexible for test engineers and system integrators especially in situations that require test case modifications. Also, the proposed software tool makes it easy to understand the various IEC 61850 services using the friendly GUI.
基金Supported by the National Science Foundation of China(Grant No.50275061)the National High Technology Research and Development Program(Grant No.2001AA423230).
文摘In this paper,a novel component based framework of test system is presented for the new requirements of dynamic changes of test functions and reconfiguration of test resources.The complexity of dynamic reconfiguration arises from the scale, redirection,extensibility and interconnection of components in test system.The paper is started by discussing the component assem- bly based framework which provide the open platform to the deploy of companents and then the script interpreter model is introduced to dynamically create the components and build the test system by analyzing XML based information of test system.A pipeline mod- el is presented to provide the data channels and behavior reflection among the components.Finally,a dynamic reconfigurable test system is implemented on the basis of COM and applied in the remote test and control system of CNC machine.
基金supported by the Special Fund for Talent of Wuhan Institute of Technology,China(No.237127)the"Fellowship for Junior Researchers"from Politecnico di Torino and Regione Piemonte,Italy
文摘The tarnishing test in the presence of hydrogen sulfide（H2S） vapors has been used to investigate the tarnish resistance capability of copper-based alloys coated with Si02-like films by means of plasma-enhanced chemical vapor deposition（PECVD） fed with a tetraethoxysilane/oxygen mixture.The chemical and morphological properties of the films have been characterized by using infrared absorption spectroscopy（IR） and scanning electron microscopy（SEM）with energy disperse spectroscopy（EDS）.The corrosion products of the samples after the tarnishing test have been identified by X-ray diffraction analysis（XRD）.It has been found that SiO2-like films formed via PECVD with a high O2 flow rate could protect copper-based alloys from H2S vapor tarnishing.The alloys coated at the O2 flow rate of 20 sccm remain uncorroded after 54days of H2S vapor tarnish testing.The corrosion products for the alloys deposited at a low O2flow rate after 54 days of tarnish testing are mainly composed of brochantite.
文摘Quality of software systems is highly demanded in today’s scenario. Highly testable system enhances the reliability also. More than 50% of test effort-time and cost are used to produce a highly testable system. Thus, design-for-testability is needed to reduce the test effort. In order to enhance the quality, productivity and reduced cost of the software organizations are promoting to produce the reuse-oriented products. Incorporating reuse technology in both aspects-software development process and test process may payoff many folds. Keeping this view, our study focus the testability of the object-oriented framework based software systems and identify that flexibility at the variable points of the object-oriented framework, chosen for framework instantiation, greatly affects the testability of object-oriented framework based software at each level of testing. In the current paper, we propose a testability model considering the flexible aspect of the variable point to estimate testability in the early phase, requirement analysis phase, of development process of the framework based software. The proposed model helps to improve the testability of the software before the implementation starts thus reducing the overall development cost.
文摘In a component-based software development life cycle, selection of preexisting components is an important task. Every component that has to be reused has an associated risk of failure of not meeting the functional and non-functional requirements. A component's failure would lead a developer to look for some other alternative of combinations of COTS, in-house and engineered components among possible candidate combinations. This means design itself can readily change. The very process of design of a software system and component selection seems to be heavily dependent on testing results. Instability of design, further, becomes more severe due to requirements change requests. Therefore, this instability of design has to be essentially mitigated by using proper design and testing approaches, otherwise, it may lead to exorbitantly high testing cost due to the repeated testing of various alternatives. How these three activities: Component-based software design, component selection and component-based software testing are interrelated? What process model is most suited to address this concern? This work explores the above questions and their implication in terms of nature of a process model that can be convincing in case of component-based software development.
基金funding by Bhabha Atomic Research Centre (BARC),Mumbai
文摘The performance of a well-designed layer of sand, and composites like layer of sand mixed with shredded rubber tire (RSM) as low cost base isolators, is studied in shake table tests in the laboratory. The building foundation is modeled by a 200 mm by 200 mm and 40 mm thick rigid plexi-glass block. The block is placed in the middle of a 1m by 1m tank filled with sand. The selected base isolator is placed between the block and the sand foundation. Accelerometers are placed on top of the footing and foundation sand layer. The displacement of the footing is also measured by LVDT. The whole setup is mounted on a shake table and subjected to sinusoidal motions with varying amplitude and frequency. Sand is found to be effective only at very high amplitude (> 0.65 g) of motions. The performance of a composite consisting of sand and 50% shredded rubber tire placed under the footing is found to be most promising as a low-cost effective base isolator.
基金This work is supported by the National Natural Science Foundation of China Education Ministry of China
文摘The corrosion resistance of the Al2O3-C based refractories in melts containing titania has been studied by quasi-station immersion and rotary immersion. The corrosionrate is decreased with the addition of graphite carbon, and ZrO2 in the refractories . The corrosion, mechanism of Al2O3-C refractories, is. the oxidization of graphite carbon by the oxides of the melts the formation of deteriorate layer, For the Al2O3-C-ZrO2 refractories, the corrosion behavior is due to the, interaction between melts and refractories . The new compounds of FeO. SiO2, SiZrO4, FeO. 3 CaO, 2CaO. SiO2 and CaO. SiO2 are formed in the deteriorate layer.
文摘This paper proposes an autopilot system that can be used to control the small scale rotorcraft during the flight test for linear-frequency-domain system identification. The input frequency-sweep is generated automatically as part of the autopilot control command. Therefore the bandwidth coverage and consistency of the frequency-sweep are guaranteed to produce high quality data for system identification. Beside that, we can set the safety parameters during the flight test （maximum roll/pitch value, minimum altitude, etc.） so the safety of the whole flight test is guaranteed. This autopilot system is validated using hardware in the loop simulator for hover flight condition.
基金National Natural Science Foundation under Grant No.51161120359Ministry of Education under Grant No.20112302110050Special Fund for Earthquake Scientific Research in the Public Interest under Grant No.201308003
文摘This article extends a signal-based approach formerly proposed by the authors, which utilizes the fractal dimension of time frequency feature （FDTFF） of displacements, for earthquake damage detection of moment resist frame （MRF）, and validates the approach with shaking table tests. The time frequency feature （TFF） of the relative displacement at measured story is defined as the real part of the coefficients of the analytical wavelet transform. The fractal dimension （FD） is to quantify the TFF within the fundamental frequency band using box counting method. It is verified that the FDTFFs at all stories of the linear MRF are identical with the help of static condensation method and modal superposition principle, while the FDTFFs at the stories with localized nonlinearities due to damage will be different from those at the stories without nonlinearities using the reverse-path methodology. By comparing the FDTFFs of displacements at measured stories in a structure, the damage-induced nonlinearity of the structure under strong ground motion can be detected and localized. Finally shaking table experiments on a 1：8 scale sixteen-story three-bay steel MRF with added frictional dampers, which generate local nonlinearities, are conducted to validate the approach.
