Side channel attack may result in user key leakage as scan test techniques are applied for crypto-graphic chips. Many secure scan designs have been proposed to protect the user key. This paper meticulously selects thr...Side channel attack may result in user key leakage as scan test techniques are applied for crypto-graphic chips. Many secure scan designs have been proposed to protect the user key. This paper meticulously selects three current scan test techniques, analyses their advantages and disadvantages and also compares them in security and area overhead. Users can choose one of them according to the requirements and further combination can be implemented to achieve better performance.展开更多
Big Data is reforming many industrial domains by providing decision support through analyzing large data volumes.Big Data testing aims to ensure that Big Data systems run smoothly and error-free while maintaining the ...Big Data is reforming many industrial domains by providing decision support through analyzing large data volumes.Big Data testing aims to ensure that Big Data systems run smoothly and error-free while maintaining the performance and quality of data.However,because of the diversity and complexity of data,testing Big Data is challenging.Though numerous research efforts deal with Big Data testing,a comprehensive review to address testing techniques and challenges of BigData is not available as yet.Therefore,we have systematically reviewed the Big Data testing techniques’evidence occurring in the period 2010–2021.This paper discusses testing data processing by highlighting the techniques used in every processing phase.Furthermore,we discuss the challenges and future directions.Our findings show that diverse functional,non-functional and combined(functional and non-functional)testing techniques have been used to solve specific problems related to Big Data.At the same time,most of the testing challenges have been faced during the MapReduce validation phase.In addition,the combinatorial testing technique is one of the most applied techniques in combination with other techniques(i.e.,random testing,mutation testing,input space partitioning and equivalence testing)to find various functional faults through Big Data testing.展开更多
Recently,researchers have shown increasing interest in combining more than one programming model into systems running on high performance computing systems(HPCs)to achieve exascale by applying parallelism at multiple ...Recently,researchers have shown increasing interest in combining more than one programming model into systems running on high performance computing systems(HPCs)to achieve exascale by applying parallelism at multiple levels.Combining different programming paradigms,such as Message Passing Interface(MPI),Open Multiple Processing(OpenMP),and Open Accelerators(OpenACC),can increase computation speed and improve performance.During the integration of multiple models,the probability of runtime errors increases,making their detection difficult,especially in the absence of testing techniques that can detect these errors.Numerous studies have been conducted to identify these errors,but no technique exists for detecting errors in three-level programming models.Despite the increasing research that integrates the three programming models,MPI,OpenMP,and OpenACC,a testing technology to detect runtime errors,such as deadlocks and race conditions,which can arise from this integration has not been developed.Therefore,this paper begins with a definition and explanation of runtime errors that result fromintegrating the three programming models that compilers cannot detect.For the first time,this paper presents a classification of operational errors that can result from the integration of the three models.This paper also proposes a parallel hybrid testing technique for detecting runtime errors in systems built in the C++programming language that uses the triple programming models MPI,OpenMP,and OpenACC.This hybrid technology combines static technology and dynamic technology,given that some errors can be detected using static techniques,whereas others can be detected using dynamic technology.The hybrid technique can detect more errors because it combines two distinct technologies.The proposed static technology detects a wide range of error types in less time,whereas a portion of the potential errors that may or may not occur depending on the 4502 CMC,2023,vol.74,no.2 operating environment are left to the dynamic technology,which completes the validation.展开更多
In this paper we present some of our recent results on applications of spectral techniques over finite fields to the problems of testing and diagnosis of computer systems.
In this paper, an inner turret moored FPSO which works in the water of 320 m depth, is selected to study the socalled "passively-truncated + numerical-simulation" type of hybrid model testing technique while the tn...In this paper, an inner turret moored FPSO which works in the water of 320 m depth, is selected to study the socalled "passively-truncated + numerical-simulation" type of hybrid model testing technique while the tnmcated water depth is 160 m and the model scale ), = 80. During the investigation, the optimization design of the equivalent-depth truncated system is performed by using the similarity of the static characteristics between the truncated system and the full depth one as the objective function. According to the truncated system, the corresponding physical test model is made. By adopting the coupling time domain simulation method, the tnmcated system model test is numerically reconstructed to carefully verify the computer simulation software and to adjust the corresponding hydrodynamic parameters. Based on the above work, the numerical extrapolation to the full depth system is performed by using the verified computer software and the adjusted hydrodyrmmic parameters. The full depth system model test is then performed in the basin and the results are compared with those from the numerical extrapolation. At last, the implementation procedure and the key technique of the hybrid model testing of the deep-sea platforms are summarized and printed. Through the above investigations, some beneficial conclusions are presented.展开更多
Objective To investigate the feasibility of acquiring the similar homogeneous enhancement using bolus-tracking techniques with shortened respiratory time in prospectively electrocardiogram-gated high-pitch spiral acqu...Objective To investigate the feasibility of acquiring the similar homogeneous enhancement using bolus-tracking techniques with shortened respiratory time in prospectively electrocardiogram-gated high-pitch spiral acquisition mode (Flash mode) coronary computed tomography angiography (CCTA) compared with test bolus technique. Methods One hundred and eighty-four consecutive patients with mean heart rate ≤65 beats per minute undergoing CCTA were prospectively included in this study. The patients were randomly divided into two groups. Patients in the group A (n=92) instructed to shorten respiratory time received CCTA using bolus-tracking technique with high-pitch spiral acquisition mode (Flash mode), while those in the group B (n=92) underwent CCTA with test bolus technique. The attenuation in the ascending aorta, image noise, contrast-to-noise ratio and radiation doses of the two groups were assessed. Results There were no significant differences in the mean attenuation values in the ascending aorta (483.18±59.07 HU vs. 498.7±83.51 HU, P=0.183), image noise (21.4±4.5 HU vs. 20.9±4.3 HU, P=0.414), contrast-to-noise ratio (12.1±4.2 vs. 13.8±5.1, P=0.31) between the groups A and B. There were no significant differences in the radiation dose of dynamic monitoring scans (0.056±0.026 mSv vs. 0.062±0.018 mSv, P=0.068) and radiation dose of angiography (0.94±0.07 mSv vs. 0.96±0.15 mSv,P=0.926) between the two groups, while 15 mL less contrast material volume was administered in the group A than the group B. Conclusion Bolus-tracking technique with shortened time of respiratory in Flash mode of dual-source CT yields the similar homogeneous enhancement with less contrast material in comparison to the test bolus technique.展开更多
Software testing is an important and cost intensive activity in software development.The major contribution in cost is due to test case generations.Requirement-based testing is an approach in which test cases are deri...Software testing is an important and cost intensive activity in software development.The major contribution in cost is due to test case generations.Requirement-based testing is an approach in which test cases are derivative from requirements without considering the implementation’s internal structure.Requirement-based testing includes functional and nonfunctional requirements.The objective of this study is to explore the approaches that generate test cases from requirements.A systematic literature review based on two research questions and extensive quality assessment criteria includes studies.The study identies 30 primary studies from 410 studies spanned from 2000 to 2018.The review’s nding shows that 53%of journal papers,42%of conference papers,and 5%of book chapters’address requirementsbased testing.Most of the studies use UML,activity,and use case diagrams for test case generation from requirements.One of the signicant lessons learned is that most software testing errors are traced back to errors in natural language requirements.A substantial amount of work focuses on UML diagrams for test case generations,which cannot capture all the system’s developed attributes.Furthermore,there is a lack of UML-based models that can generate test cases from natural language requirements by rening them in context.Coverage criteria indicate how efciently the testing has been performed 12.37%of studies use requirements coverage,20%of studies cover path coverage,and 17%study basic coverage.展开更多
As great progress has been made in the field of protection of new plant varieties, more attention is paid to the standardization of DUS(Distinctness, Uniformity, and Stability) test procedure. For further studies of t...As great progress has been made in the field of protection of new plant varieties, more attention is paid to the standardization of DUS(Distinctness, Uniformity, and Stability) test procedure. For further studies of tropical plants as their importance in agriculture and germplasm, protection of coconut becomes more significant and thus DUS test technique of coconut is needed. In this essay, we analyzed the status quo of the DUS test guidelines by International Union for the Protection of New Varieties of Plants(UPOV proj.3) and national DUS test guidelines in China, and provided some suggestions or promotions for improving the guidelines of DUS test in coconut.展开更多
Ⅰ The Indexes of Detecting Oil and Gas Resources The deeply buried reservoir which in a dynamic equilibrium state has a great pressure inside, and between it and earth surface there is a great difference of pressure....Ⅰ The Indexes of Detecting Oil and Gas Resources The deeply buried reservoir which in a dynamic equilibrium state has a great pressure inside, and between it and earth surface there is a great difference of pressure. Therefore the hydrocarbon must spread and move vertically to the surface along the pressure gradient orientation. Hydrocarbons in the reservoir along some small rifts, cracks, joints and cleavages penetrate the overlying strata and seepage onto the surface. Thus the hydrocarbons become unvisble oil and gas signs. This process is called the phenomena of hydrocarbon microseepage of reservoir. Hydrocarbons microseepage in the process展开更多
By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When a...By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When an unlimited extensive incubation period with zero creep rate oc-curred. the stress cavsing zero creep rate is defined as fatigue-creep resistance. The developped test-ing technique was used to measure the fatigue-creep resistance in F anc C regions. The dynamic ef-fective stress could yield a better descrption of fatigue and creep interaction. The fatigue-creep rateequations with varied exponents inF of C region are established. The different deformation mecha-nisms in F or C regions are indicated展开更多
A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted....A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.展开更多
Hybrid model testing technique is widely used in verification of a deepwater floating structure and its mooring system, but the design of the truncated mooring systems which can reproduce both static and dynamic respo...Hybrid model testing technique is widely used in verification of a deepwater floating structure and its mooring system, but the design of the truncated mooring systems which can reproduce both static and dynamic response same as the full-depth mooring system is still a big challenge, especially for the mooring systems with large truncation. A Cell-Truss Spar operated in 1500 m water depth is verified in a wave basin with 4 m water depth. A large truncation factor arises even though a small model scale 1 : 100 is adopted. Computer program modules for analyzing the static and frequency domain dynamic response of mooting line are combined with multi-objective genetic algorithm NSGA-II to optimize the truncated mooring system. Considering the asyrmnetry of layout of mooring lines, two different truncated mooring systems are respectively designed for both directions in which the restoring forces of the mooring system are quite different. Not only the static characteristics of the mooring systems are calibrated, but also the dynamic responses of the single truncated mooring line are evaluated through time domain numerical simulation and model tests. The model test results of 100-year storm in the GOM are reconstructed and extrapolated to a full depth. It is found that the experimental and numerical resuits of Spar wave frequency motion agree well, and the dynamic responses of the full-depth mooring lines are better reproduced, but the low frequency surge motion is overestimated due to the smaller mooring-induced damping. It is a feasible method adopting different tnmcated mooring systems for different directions in which the restoring force characteristics are quite different and cannot be simulated by one truncated mooring system. Hybrid verification of a deepwater platform in wave basin with shallow water depth is still feasible if the truncated mooring systems are properly designed, and numerical extrapolation is necessary.展开更多
In the paper, the variable separation approach, homoclinic test technique and bilinear method are successfullyextended to a (1+1)-dimensional Caudry-Dodd-Gibbon-Sawada-Kortera (CDGSK) system, respectively.Basedon the ...In the paper, the variable separation approach, homoclinic test technique and bilinear method are successfullyextended to a (1+1)-dimensional Caudry-Dodd-Gibbon-Sawada-Kortera (CDGSK) system, respectively.Basedon the derived exact solutions, some significant types of localized excitations such as standing waves, periodic waves,solitary waves are simultaneously derived from the (1+1)-dimensional Caudry-Dodd-Gibbon-Sawada-Kortera systemby entrancing appropriate parameters.展开更多
An efficient method for helicopter rotor fault diagnosis was proposed using diagnostic matrix and its software framework was developed.The diagnostic matrix was extracted by the way of simulating the quantitative mode...An efficient method for helicopter rotor fault diagnosis was proposed using diagnostic matrix and its software framework was developed.The diagnostic matrix was extracted by the way of simulating the quantitative models of damaged and undamaged rotor systems.The conflicts were recognized by the virtual symptom sensor based on the dependencies between symptoms and faults.Diagnostic candidates were generated by the Boolean hitting algorithm.The proposed method provides multi-fault real-time diagnostic capability and it is suitable for the synthetic health monitoring of complex systems.展开更多
With the development of green tribology in the shipping industry,the application of water lubrication gradually replaces oil lubrication in stern bearings and thrust bearings.In terms of large-scale and high-speed shi...With the development of green tribology in the shipping industry,the application of water lubrication gradually replaces oil lubrication in stern bearings and thrust bearings.In terms of large-scale and high-speed ships,water-lubricated bearings with high performance are more strictly required.However,due to the lubricating medium,water-lubricated bearings have many problems such as friction,wear,vibration,noise,etc.This review focuses on the performance of marine water-lubricated bearings and their failure prevention mechanism.Furthermore,the research of marine water-lubricated bearings is reviewed by discussing its lubrication principle,test technology,friction and wear mechanism,and friction noise generation mechanism.The performance enhancement methods have been overviewed from structure optimization and material modification.Finally,the potential problems and the perspective of water-lubricated bearings are given in detail.展开更多
Tianiin Automotive Test Center has a test capability as well as a capability of conducting universality techniques research. With fixed assets of around RMB 76.44 million yuan and an architectural area of 11,200 sqm, ...Tianiin Automotive Test Center has a test capability as well as a capability of conducting universality techniques research. With fixed assets of around RMB 76.44 million yuan and an architectural area of 11,200 sqm, test labs mainly include: auto emission test lab, full-scale vehicle crash test lab, auto safety test lab, auto lighting and view field test lab, engine test lab,展开更多
Acoustic-pulse compression is obtained in systems with different timebandwidth products by applying the digital matched-filter technique to ultrasonic non-destructive testing. The signal is linearly frequency -modulat...Acoustic-pulse compression is obtained in systems with different timebandwidth products by applying the digital matched-filter technique to ultrasonic non-destructive testing. The signal is linearly frequency -modulated (LFM) pulse and the digitized electrical-excitation signal itself is used as a digital matched filter. Experimental results are in good agreement with theory. Suppressions of side lobes achieve -41.9 dB and -41.5 dB for the Hamming and Gaussian weighted signals respectively. It shows that the application of the digital matched-filter technique improves the performances of a ultrasonic testing system explicitly.展开更多
The application of pile-end post-grouting piles for super-large bridge pile foundations in some important projects was introduced in this paper.There are totally 21 test piles.The maximum pile diameter varies from 2.5...The application of pile-end post-grouting piles for super-large bridge pile foundations in some important projects was introduced in this paper.There are totally 21 test piles.The maximum pile diameter varies from 2.5 m to 3 m,and the maximum length is 125m;the bearing capacity of the post-grouting piles is over ten thousands tons.Based on the test results,the bearing capacity,displacement,and beating characteristics before and after grouting were analyzed.The results show that the beating capacity of the piles is increased in different degrees after grouting although the technical parameters,including the patterns of grouting pipes,pressure,dosages of cement,duration of grouting lasting time,are different.However,the obtained values are very discrete.In addition,the calculation formula for the post-grouting piles under specified grouting condition was deduced based on the statistics analysis results of 57 test piles.The research results have been applied in the design of bridge foundation.展开更多
文摘Side channel attack may result in user key leakage as scan test techniques are applied for crypto-graphic chips. Many secure scan designs have been proposed to protect the user key. This paper meticulously selects three current scan test techniques, analyses their advantages and disadvantages and also compares them in security and area overhead. Users can choose one of them according to the requirements and further combination can be implemented to achieve better performance.
基金Science Foundation Ireland(SFI)under Grant Number SFI/16/RC/3918(Confirm)and Marie Sklodowska Curie Grant agreement No.847577 co-fundedthe European Regional Development Fund.Wasif Afzal has received funding from the European Union’s Horizon 2020 research and innovation program under CMC,2023,vol.74,no.22767 Grant agreement Nos.871319,957212from the ECSEL Joint Undertaking(JU)under Grant agreement No 101007350.
文摘Big Data is reforming many industrial domains by providing decision support through analyzing large data volumes.Big Data testing aims to ensure that Big Data systems run smoothly and error-free while maintaining the performance and quality of data.However,because of the diversity and complexity of data,testing Big Data is challenging.Though numerous research efforts deal with Big Data testing,a comprehensive review to address testing techniques and challenges of BigData is not available as yet.Therefore,we have systematically reviewed the Big Data testing techniques’evidence occurring in the period 2010–2021.This paper discusses testing data processing by highlighting the techniques used in every processing phase.Furthermore,we discuss the challenges and future directions.Our findings show that diverse functional,non-functional and combined(functional and non-functional)testing techniques have been used to solve specific problems related to Big Data.At the same time,most of the testing challenges have been faced during the MapReduce validation phase.In addition,the combinatorial testing technique is one of the most applied techniques in combination with other techniques(i.e.,random testing,mutation testing,input space partitioning and equivalence testing)to find various functional faults through Big Data testing.
基金[King Abdulaziz University][Deanship of Scientific Research]Grant Number[KEP-PHD-20-611-42].
文摘Recently,researchers have shown increasing interest in combining more than one programming model into systems running on high performance computing systems(HPCs)to achieve exascale by applying parallelism at multiple levels.Combining different programming paradigms,such as Message Passing Interface(MPI),Open Multiple Processing(OpenMP),and Open Accelerators(OpenACC),can increase computation speed and improve performance.During the integration of multiple models,the probability of runtime errors increases,making their detection difficult,especially in the absence of testing techniques that can detect these errors.Numerous studies have been conducted to identify these errors,but no technique exists for detecting errors in three-level programming models.Despite the increasing research that integrates the three programming models,MPI,OpenMP,and OpenACC,a testing technology to detect runtime errors,such as deadlocks and race conditions,which can arise from this integration has not been developed.Therefore,this paper begins with a definition and explanation of runtime errors that result fromintegrating the three programming models that compilers cannot detect.For the first time,this paper presents a classification of operational errors that can result from the integration of the three models.This paper also proposes a parallel hybrid testing technique for detecting runtime errors in systems built in the C++programming language that uses the triple programming models MPI,OpenMP,and OpenACC.This hybrid technology combines static technology and dynamic technology,given that some errors can be detected using static techniques,whereas others can be detected using dynamic technology.The hybrid technique can detect more errors because it combines two distinct technologies.The proposed static technology detects a wide range of error types in less time,whereas a portion of the potential errors that may or may not occur depending on the 4502 CMC,2023,vol.74,no.2 operating environment are left to the dynamic technology,which completes the validation.
基金This work was supported by the National Science Foundation(USA)under grant MIP 9630096the NATO under Grant 910411Volkswagen Foundation(Germany)
文摘In this paper we present some of our recent results on applications of spectral techniques over finite fields to the problems of testing and diagnosis of computer systems.
基金This work was financially supported by the National Natural Science Foundation of China (Grant No10602055)Nature Science Foundation of China Jiliang University (Grant No XZ0501)
文摘In this paper, an inner turret moored FPSO which works in the water of 320 m depth, is selected to study the socalled "passively-truncated + numerical-simulation" type of hybrid model testing technique while the tnmcated water depth is 160 m and the model scale ), = 80. During the investigation, the optimization design of the equivalent-depth truncated system is performed by using the similarity of the static characteristics between the truncated system and the full depth one as the objective function. According to the truncated system, the corresponding physical test model is made. By adopting the coupling time domain simulation method, the tnmcated system model test is numerically reconstructed to carefully verify the computer simulation software and to adjust the corresponding hydrodynamic parameters. Based on the above work, the numerical extrapolation to the full depth system is performed by using the verified computer software and the adjusted hydrodyrmmic parameters. The full depth system model test is then performed in the basin and the results are compared with those from the numerical extrapolation. At last, the implementation procedure and the key technique of the hybrid model testing of the deep-sea platforms are summarized and printed. Through the above investigations, some beneficial conclusions are presented.
基金Supported by the Ministry of Science and Technology of Inner Mongolia, China (20110504)
文摘Objective To investigate the feasibility of acquiring the similar homogeneous enhancement using bolus-tracking techniques with shortened respiratory time in prospectively electrocardiogram-gated high-pitch spiral acquisition mode (Flash mode) coronary computed tomography angiography (CCTA) compared with test bolus technique. Methods One hundred and eighty-four consecutive patients with mean heart rate ≤65 beats per minute undergoing CCTA were prospectively included in this study. The patients were randomly divided into two groups. Patients in the group A (n=92) instructed to shorten respiratory time received CCTA using bolus-tracking technique with high-pitch spiral acquisition mode (Flash mode), while those in the group B (n=92) underwent CCTA with test bolus technique. The attenuation in the ascending aorta, image noise, contrast-to-noise ratio and radiation doses of the two groups were assessed. Results There were no significant differences in the mean attenuation values in the ascending aorta (483.18±59.07 HU vs. 498.7±83.51 HU, P=0.183), image noise (21.4±4.5 HU vs. 20.9±4.3 HU, P=0.414), contrast-to-noise ratio (12.1±4.2 vs. 13.8±5.1, P=0.31) between the groups A and B. There were no significant differences in the radiation dose of dynamic monitoring scans (0.056±0.026 mSv vs. 0.062±0.018 mSv, P=0.068) and radiation dose of angiography (0.94±0.07 mSv vs. 0.96±0.15 mSv,P=0.926) between the two groups, while 15 mL less contrast material volume was administered in the group A than the group B. Conclusion Bolus-tracking technique with shortened time of respiratory in Flash mode of dual-source CT yields the similar homogeneous enhancement with less contrast material in comparison to the test bolus technique.
文摘Software testing is an important and cost intensive activity in software development.The major contribution in cost is due to test case generations.Requirement-based testing is an approach in which test cases are derivative from requirements without considering the implementation’s internal structure.Requirement-based testing includes functional and nonfunctional requirements.The objective of this study is to explore the approaches that generate test cases from requirements.A systematic literature review based on two research questions and extensive quality assessment criteria includes studies.The study identies 30 primary studies from 410 studies spanned from 2000 to 2018.The review’s nding shows that 53%of journal papers,42%of conference papers,and 5%of book chapters’address requirementsbased testing.Most of the studies use UML,activity,and use case diagrams for test case generation from requirements.One of the signicant lessons learned is that most software testing errors are traced back to errors in natural language requirements.A substantial amount of work focuses on UML diagrams for test case generations,which cannot capture all the system’s developed attributes.Furthermore,there is a lack of UML-based models that can generate test cases from natural language requirements by rening them in context.Coverage criteria indicate how efciently the testing has been performed 12.37%of studies use requirements coverage,20%of studies cover path coverage,and 17%study basic coverage.
基金Supported by Special Fund for Scientific Research in the Public Interest of Ministry of Agriculture(200903008-15)
文摘As great progress has been made in the field of protection of new plant varieties, more attention is paid to the standardization of DUS(Distinctness, Uniformity, and Stability) test procedure. For further studies of tropical plants as their importance in agriculture and germplasm, protection of coconut becomes more significant and thus DUS test technique of coconut is needed. In this essay, we analyzed the status quo of the DUS test guidelines by International Union for the Protection of New Varieties of Plants(UPOV proj.3) and national DUS test guidelines in China, and provided some suggestions or promotions for improving the guidelines of DUS test in coconut.
文摘Ⅰ The Indexes of Detecting Oil and Gas Resources The deeply buried reservoir which in a dynamic equilibrium state has a great pressure inside, and between it and earth surface there is a great difference of pressure. Therefore the hydrocarbon must spread and move vertically to the surface along the pressure gradient orientation. Hydrocarbons in the reservoir along some small rifts, cracks, joints and cleavages penetrate the overlying strata and seepage onto the surface. Thus the hydrocarbons become unvisble oil and gas signs. This process is called the phenomena of hydrocarbon microseepage of reservoir. Hydrocarbons microseepage in the process
文摘By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When an unlimited extensive incubation period with zero creep rate oc-curred. the stress cavsing zero creep rate is defined as fatigue-creep resistance. The developped test-ing technique was used to measure the fatigue-creep resistance in F anc C regions. The dynamic ef-fective stress could yield a better descrption of fatigue and creep interaction. The fatigue-creep rateequations with varied exponents inF of C region are established. The different deformation mecha-nisms in F or C regions are indicated
文摘A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.
基金supported by the National High Technology Research and Development Program of China(863 Program, Grant No.2006AA09A107)
文摘Hybrid model testing technique is widely used in verification of a deepwater floating structure and its mooring system, but the design of the truncated mooring systems which can reproduce both static and dynamic response same as the full-depth mooring system is still a big challenge, especially for the mooring systems with large truncation. A Cell-Truss Spar operated in 1500 m water depth is verified in a wave basin with 4 m water depth. A large truncation factor arises even though a small model scale 1 : 100 is adopted. Computer program modules for analyzing the static and frequency domain dynamic response of mooting line are combined with multi-objective genetic algorithm NSGA-II to optimize the truncated mooring system. Considering the asyrmnetry of layout of mooring lines, two different truncated mooring systems are respectively designed for both directions in which the restoring forces of the mooring system are quite different. Not only the static characteristics of the mooring systems are calibrated, but also the dynamic responses of the single truncated mooring line are evaluated through time domain numerical simulation and model tests. The model test results of 100-year storm in the GOM are reconstructed and extrapolated to a full depth. It is found that the experimental and numerical resuits of Spar wave frequency motion agree well, and the dynamic responses of the full-depth mooring lines are better reproduced, but the low frequency surge motion is overestimated due to the smaller mooring-induced damping. It is a feasible method adopting different tnmcated mooring systems for different directions in which the restoring force characteristics are quite different and cannot be simulated by one truncated mooring system. Hybrid verification of a deepwater platform in wave basin with shallow water depth is still feasible if the truncated mooring systems are properly designed, and numerical extrapolation is necessary.
基金Supported the Natural Science Foundation of Guangdong Province of China under Grant No.10151200501000008 the Special Foundation of Talent Engineering of Guangdong Province+2 种基金the Scientific Research Foundation of Key Discipline of Guangdong Shaoguan University under Grant No.KZ2009001the Natural Science Foundation of Zhejiang Province of China under Grant Nos.Y604106 and Y606181the Foundation of New Century "151 Talent Engineering" of Zhejiang Province
文摘In the paper, the variable separation approach, homoclinic test technique and bilinear method are successfullyextended to a (1+1)-dimensional Caudry-Dodd-Gibbon-Sawada-Kortera (CDGSK) system, respectively.Basedon the derived exact solutions, some significant types of localized excitations such as standing waves, periodic waves,solitary waves are simultaneously derived from the (1+1)-dimensional Caudry-Dodd-Gibbon-Sawada-Kortera systemby entrancing appropriate parameters.
文摘An efficient method for helicopter rotor fault diagnosis was proposed using diagnostic matrix and its software framework was developed.The diagnostic matrix was extracted by the way of simulating the quantitative models of damaged and undamaged rotor systems.The conflicts were recognized by the virtual symptom sensor based on the dependencies between symptoms and faults.Diagnostic candidates were generated by the Boolean hitting algorithm.The proposed method provides multi-fault real-time diagnostic capability and it is suitable for the synthetic health monitoring of complex systems.
基金financially supported by the National Key R&D Program of China(No.2018YFE0197600)National Natural Science Foundation of China(No.52071244).
文摘With the development of green tribology in the shipping industry,the application of water lubrication gradually replaces oil lubrication in stern bearings and thrust bearings.In terms of large-scale and high-speed ships,water-lubricated bearings with high performance are more strictly required.However,due to the lubricating medium,water-lubricated bearings have many problems such as friction,wear,vibration,noise,etc.This review focuses on the performance of marine water-lubricated bearings and their failure prevention mechanism.Furthermore,the research of marine water-lubricated bearings is reviewed by discussing its lubrication principle,test technology,friction and wear mechanism,and friction noise generation mechanism.The performance enhancement methods have been overviewed from structure optimization and material modification.Finally,the potential problems and the perspective of water-lubricated bearings are given in detail.
文摘Tianiin Automotive Test Center has a test capability as well as a capability of conducting universality techniques research. With fixed assets of around RMB 76.44 million yuan and an architectural area of 11,200 sqm, test labs mainly include: auto emission test lab, full-scale vehicle crash test lab, auto safety test lab, auto lighting and view field test lab, engine test lab,
文摘Acoustic-pulse compression is obtained in systems with different timebandwidth products by applying the digital matched-filter technique to ultrasonic non-destructive testing. The signal is linearly frequency -modulated (LFM) pulse and the digitized electrical-excitation signal itself is used as a digital matched filter. Experimental results are in good agreement with theory. Suppressions of side lobes achieve -41.9 dB and -41.5 dB for the Hamming and Gaussian weighted signals respectively. It shows that the application of the digital matched-filter technique improves the performances of a ultrasonic testing system explicitly.
基金The research was supported by China State Science and Technology Supporting Program(No.2006BAG04B01).
文摘The application of pile-end post-grouting piles for super-large bridge pile foundations in some important projects was introduced in this paper.There are totally 21 test piles.The maximum pile diameter varies from 2.5 m to 3 m,and the maximum length is 125m;the bearing capacity of the post-grouting piles is over ten thousands tons.Based on the test results,the bearing capacity,displacement,and beating characteristics before and after grouting were analyzed.The results show that the beating capacity of the piles is increased in different degrees after grouting although the technical parameters,including the patterns of grouting pipes,pressure,dosages of cement,duration of grouting lasting time,are different.However,the obtained values are very discrete.In addition,the calculation formula for the post-grouting piles under specified grouting condition was deduced based on the statistics analysis results of 57 test piles.The research results have been applied in the design of bridge foundation.