Aluminium matrix surface composites are gaining alluring role especially in aerospace, defence, and marine industries. Friction stir processing(FSP) is a promising novel solid state technique for surface composites fa...Aluminium matrix surface composites are gaining alluring role especially in aerospace, defence, and marine industries. Friction stir processing(FSP) is a promising novel solid state technique for surface composites fabrication. In this study, AA6061/SiC surface composites were fabricated and the effect of tool plunge depth on pattern of reinforcement particles dispersion in metal matrix was investigated. Six varying tool plunge depths were chosen at constant levels of shoulder diameter and tool tilt angle to observe the exclusive effect of plunge variation. Process parameters chosen for the experimentation are speed of rotation, travel speed and tool tilt angle which were taken as 1400 rpm, 40 mm/min, and 2.5 °respectively. Macro and the microstructural study were performed using stereo zoom and optical microscope respectively. Results reflected that lower plunge depth levels lead to insufficient heat generation and cavity formation towards the stir zone center. On the other hand, higher levels of plunge depth result in ejection of reinforcement particles and even sticking of material to tool shoulder. Thus, an optimal plunge depth is needed in developing defect free surface composites.展开更多
The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus m...The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus massoniana forest natural watershed. The runoff volumes of Eucalyptus plantations and P. massoniana forest natural watersheds were continuously monitored using the small watershed runoff monitoring method and the automatic data collection devices from August,2013 to December,2016,and effects of heavy rainfall and continuous rainfall on the runoff process were studied. Results showed that the annual runoff coefficient of Eucalyptus plantations natural watershed was 0. 050,and 55. 4% lower than P. massoniana forest（ 0. 112）,with the difference being significant（ P 〈 0. 01）. Total runoff duration,time of maximum runoff lagging behind rainfall peak,and runoff duration caused by a heavy rainfall process（ amounting to 147. 5 mm） between the two kinds of forest watersheds were significant different,those of Eucalyptus plantations were 35. 6 mm,0. 2 h and 13. 8 h,respectively,while those of P. massoniana forest were28. 5 mm,0. 7 h and 35. 5 h,respectively. Eucalyptus plantations natural watershed produced only 4-days runoff,and runoff depth amounted to3. 8 mm with a 7-days continuous precipitation process of rainfall with 125. 0 mm,while P. massoniana forest natural watershed produced continuously 13-days runoff,and the runoff depth was 10. 1 mm. In conclusion,water conservation capacity of Eucalyptus plantations is obviously lower than P. massoniana forest.展开更多
Case depth measurement of the induction hardened steel parts is necessary for quality control. Vickers microhardness test is the most industrially accepted method to identify the case depth. But this method is a time ...Case depth measurement of the induction hardened steel parts is necessary for quality control. Vickers microhardness test is the most industrially accepted method to identify the case depth. But this method is a time consuming one and it requires expensive equipment. The aim of this study is to develop a different method to determine the case depth using image processing. The surface hardened steel samples were cross cut, ground and etched with Nital. The etched macrosectioned specimens were scanned by a scanner. The scanned images were evaluated by the developed software. The principle of the software is to identify the gray level difference. The effective case depths of the surface hardened specimens obtained by Vickers microhardness test and the developed method were compared. It was found that the deviation of the developed method was ±0.12 mm at the case depth range of 0.6 - 2.0 mm and mm at the case depth range of 2.1 - 4.3 mm. The measuring time was only 20% of Vickers microhardness test. The deviation range is much lower than the tolerance case depth specification for induction hardening in general.展开更多
Organizational computing devices are increasingly becoming targets of cyber-attacks, and organizations have become dependent on the safety and security of their computer networks and their organizational computing dev...Organizational computing devices are increasingly becoming targets of cyber-attacks, and organizations have become dependent on the safety and security of their computer networks and their organizational computing devices. Business and government often use defense in-depth information assurance measures such as firewalls, intrusion detection systems, and password procedures across their enterprises to plan strategically and manage IT security risks. This quantitative study explores whether the analytical hierarchy process (AHP) model can be effectively applied to the prioritization of information assurance defense in-depth measures. In response to these threats, the President, legislators, experts, and others have characterized cyber security as a pressing national security issue. The methods used in this study consisted of emailing study participants a survey requesting that they prioritize five defense in-depth information assurance measures, anti-virus, intrusion detection, password, smart-cards, and encryption, with a range of responses from 1 - 5 using a Likert scale to consider standard cost, effectiveness, and perceived ease of use in terms of protection of organizational computing devices. The measures were then weighted, based on ranking. A pair-wise comparison of each of the five measures is then made using AHP to determine whether the Likert scale and the AHP model could be effectively applied to the prioritization of information assurance measures to protect organizational computing devices. The findings of the research reject the H0 null hypothesis that AHP does not affect the relationship between the information technology analysts’ prioritization of five defense in-depth dependent variables and the independent variables of cost, ease of use, and effectiveness in protecting organizational devices against cyber-attacks.展开更多
Thermo-luminescence （TL） is a kind of luminescence decay measured with varying temperature. In the process of TL the decay parameter itself involves the temperature effect of traps. Thus the trap depth is inseparabl...Thermo-luminescence （TL） is a kind of luminescence decay measured with varying temperature. In the process of TL the decay parameter itself involves the temperature effect of traps. Thus the trap depth is inseparable from the decay parameter. There are two separate peaks in the TL curve of ZnS：Cu,Co if the measurement starts from liquid nitrogen temperature. In the experiment we started from zero Celsius temperature to isolate the deeper traps. We have proposed and realized three methods for simultaneous determination of trap depth and decay parameter based on the quasi-equilibrium model and experimental data. If we treat the case of kinetic order a = 1 as a = 2, the error might be as large as 100%.展开更多
This paper bursts the bondage of conventional no-burn thought, presents an optimum strategy permitting burn appear in grinding roughing stage, but the burning layer can be summed on the following finishing stage. On t...This paper bursts the bondage of conventional no-burn thought, presents an optimum strategy permitting burn appear in grinding roughing stage, but the burning layer can be summed on the following finishing stage. On the base of the basic grinding models, the objective function and constrained functions for the multiparameter optimum grinding models had been built in this paper. By the computer simulation, the nonlinear optimum grinding control parameters had been obtained, and the truth grinding process had been controlled by these parameters. The results of simulation and the experiments proved the exactitude of the optimum models and the feasibility of the optimum strategy. This paper had also created the precondition for the grinding automation, virtual grinding and intelligent grinding system for cylindrical grinding process.展开更多
In this paper, spectral hole depth dependence on temperature below 10 K in Tm^3＋ ：YAG crystal is investigated in detail. A novel model is proposed to analyze the temperature dependence on the spectral hole. By using...In this paper, spectral hole depth dependence on temperature below 10 K in Tm^3＋ ：YAG crystal is investigated in detail. A novel model is proposed to analyze the temperature dependence on the spectral hole. By using the proposed model, we theoretically deduce the temperature dependence of spectral hole depth. The results are compared with experimental results and they are in good agreement. According to the theoretic results, the optimum temperature in experiment can be found.展开更多
This article adopts three artificial intelligence techniques, Gaussian Process Regression（GPR）, Least Square Support Vector Machine（LSSVM） and Extreme Learning Machine（ELM）, for prediction of rock depth（d） at ...This article adopts three artificial intelligence techniques, Gaussian Process Regression（GPR）, Least Square Support Vector Machine（LSSVM） and Extreme Learning Machine（ELM）, for prediction of rock depth（d） at any point in Chennai. GPR, ELM and LSSVM have been used as regression techniques.Latitude and longitude are also adopted as inputs of the GPR, ELM and LSSVM models. The performance of the ELM, GPR and LSSVM models has been compared. The developed ELM, GPR and LSSVM models produce spatial variability of rock depth and offer robust models for the prediction of rock depth.展开更多
An analytical scheme on the initial transient process in a simple helical flux compression generator, which includes the distributions of both the magnetic field in the hollow of an armature and the conducting current...An analytical scheme on the initial transient process in a simple helical flux compression generator, which includes the distributions of both the magnetic field in the hollow of an armature and the conducting current density in the stator, is developed by means of a diffusion equation. A relationship between frequency of the conducting current, root of the characteristic function of Bessel equation and decay time in the armature is given. The skin depth in the helical stator is calculated and is compared with the approximate one which is widely used in the calculation of magnetic diffusion. Our analytical results are helpful to understanding the mechanism of the loss of magnetic flux in both the armature and stator and to suggesting an optimal design for improving performance of the helical flux compression generator.展开更多
基金the University Grants Commission (UGC) for its financial assistance (vide sanction order No. F.3-40/2012 (SAP-II) under its SAP (DRS-I) sanctioned to the Department of Mechanical Engineering for the project entitled Friction Stir Welding, Ultrasonic Machining
文摘Aluminium matrix surface composites are gaining alluring role especially in aerospace, defence, and marine industries. Friction stir processing(FSP) is a promising novel solid state technique for surface composites fabrication. In this study, AA6061/SiC surface composites were fabricated and the effect of tool plunge depth on pattern of reinforcement particles dispersion in metal matrix was investigated. Six varying tool plunge depths were chosen at constant levels of shoulder diameter and tool tilt angle to observe the exclusive effect of plunge variation. Process parameters chosen for the experimentation are speed of rotation, travel speed and tool tilt angle which were taken as 1400 rpm, 40 mm/min, and 2.5 °respectively. Macro and the microstructural study were performed using stereo zoom and optical microscope respectively. Results reflected that lower plunge depth levels lead to insufficient heat generation and cavity formation towards the stir zone center. On the other hand, higher levels of plunge depth result in ejection of reinforcement particles and even sticking of material to tool shoulder. Thus, an optimal plunge depth is needed in developing defect free surface composites.
基金Supported by Special Project for Scientific Research of Public Welfare Industry of Ministry of Water Resources(201301044)
文摘The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus massoniana forest natural watershed. The runoff volumes of Eucalyptus plantations and P. massoniana forest natural watersheds were continuously monitored using the small watershed runoff monitoring method and the automatic data collection devices from August,2013 to December,2016,and effects of heavy rainfall and continuous rainfall on the runoff process were studied. Results showed that the annual runoff coefficient of Eucalyptus plantations natural watershed was 0. 050,and 55. 4% lower than P. massoniana forest（ 0. 112）,with the difference being significant（ P 〈 0. 01）. Total runoff duration,time of maximum runoff lagging behind rainfall peak,and runoff duration caused by a heavy rainfall process（ amounting to 147. 5 mm） between the two kinds of forest watersheds were significant different,those of Eucalyptus plantations were 35. 6 mm,0. 2 h and 13. 8 h,respectively,while those of P. massoniana forest were28. 5 mm,0. 7 h and 35. 5 h,respectively. Eucalyptus plantations natural watershed produced only 4-days runoff,and runoff depth amounted to3. 8 mm with a 7-days continuous precipitation process of rainfall with 125. 0 mm,while P. massoniana forest natural watershed produced continuously 13-days runoff,and the runoff depth was 10. 1 mm. In conclusion,water conservation capacity of Eucalyptus plantations is obviously lower than P. massoniana forest.
文摘Case depth measurement of the induction hardened steel parts is necessary for quality control. Vickers microhardness test is the most industrially accepted method to identify the case depth. But this method is a time consuming one and it requires expensive equipment. The aim of this study is to develop a different method to determine the case depth using image processing. The surface hardened steel samples were cross cut, ground and etched with Nital. The etched macrosectioned specimens were scanned by a scanner. The scanned images were evaluated by the developed software. The principle of the software is to identify the gray level difference. The effective case depths of the surface hardened specimens obtained by Vickers microhardness test and the developed method were compared. It was found that the deviation of the developed method was ±0.12 mm at the case depth range of 0.6 - 2.0 mm and mm at the case depth range of 2.1 - 4.3 mm. The measuring time was only 20% of Vickers microhardness test. The deviation range is much lower than the tolerance case depth specification for induction hardening in general.
文摘Organizational computing devices are increasingly becoming targets of cyber-attacks, and organizations have become dependent on the safety and security of their computer networks and their organizational computing devices. Business and government often use defense in-depth information assurance measures such as firewalls, intrusion detection systems, and password procedures across their enterprises to plan strategically and manage IT security risks. This quantitative study explores whether the analytical hierarchy process (AHP) model can be effectively applied to the prioritization of information assurance defense in-depth measures. In response to these threats, the President, legislators, experts, and others have characterized cyber security as a pressing national security issue. The methods used in this study consisted of emailing study participants a survey requesting that they prioritize five defense in-depth information assurance measures, anti-virus, intrusion detection, password, smart-cards, and encryption, with a range of responses from 1 - 5 using a Likert scale to consider standard cost, effectiveness, and perceived ease of use in terms of protection of organizational computing devices. The measures were then weighted, based on ranking. A pair-wise comparison of each of the five measures is then made using AHP to determine whether the Likert scale and the AHP model could be effectively applied to the prioritization of information assurance measures to protect organizational computing devices. The findings of the research reject the H0 null hypothesis that AHP does not affect the relationship between the information technology analysts’ prioritization of five defense in-depth dependent variables and the independent variables of cost, ease of use, and effectiveness in protecting organizational devices against cyber-attacks.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10374001, 10434030 and 60576016）, the State Key Development Program for Basic Research of China （Grant No 2003CB314707）, the Excellent Doctor＇s Science and Technology Innovation Foundation of Beijing Jiaotong University （Grant No 48011）, Russian Foundation of Basic Research （Grant Nos 04-02- 16942 and 02-02-39007）.
文摘Thermo-luminescence （TL） is a kind of luminescence decay measured with varying temperature. In the process of TL the decay parameter itself involves the temperature effect of traps. Thus the trap depth is inseparable from the decay parameter. There are two separate peaks in the TL curve of ZnS：Cu,Co if the measurement starts from liquid nitrogen temperature. In the experiment we started from zero Celsius temperature to isolate the deeper traps. We have proposed and realized three methods for simultaneous determination of trap depth and decay parameter based on the quasi-equilibrium model and experimental data. If we treat the case of kinetic order a = 1 as a = 2, the error might be as large as 100%.
文摘This paper bursts the bondage of conventional no-burn thought, presents an optimum strategy permitting burn appear in grinding roughing stage, but the burning layer can be summed on the following finishing stage. On the base of the basic grinding models, the objective function and constrained functions for the multiparameter optimum grinding models had been built in this paper. By the computer simulation, the nonlinear optimum grinding control parameters had been obtained, and the truth grinding process had been controlled by these parameters. The results of simulation and the experiments proved the exactitude of the optimum models and the feasibility of the optimum strategy. This paper had also created the precondition for the grinding automation, virtual grinding and intelligent grinding system for cylindrical grinding process.
基金supported by the National Natural Science Foundation of China (Grant No. 11004152)the Science Fund of Tianjin Education Commission (Grant Nos. 20090715 and 20110704)
文摘In this paper, spectral hole depth dependence on temperature below 10 K in Tm^3＋ ：YAG crystal is investigated in detail. A novel model is proposed to analyze the temperature dependence on the spectral hole. By using the proposed model, we theoretically deduce the temperature dependence of spectral hole depth. The results are compared with experimental results and they are in good agreement. According to the theoretic results, the optimum temperature in experiment can be found.
文摘This article adopts three artificial intelligence techniques, Gaussian Process Regression（GPR）, Least Square Support Vector Machine（LSSVM） and Extreme Learning Machine（ELM）, for prediction of rock depth（d） at any point in Chennai. GPR, ELM and LSSVM have been used as regression techniques.Latitude and longitude are also adopted as inputs of the GPR, ELM and LSSVM models. The performance of the ELM, GPR and LSSVM models has been compared. The developed ELM, GPR and LSSVM models produce spatial variability of rock depth and offer robust models for the prediction of rock depth.
基金Project supported by the National Natural Science Foundation of China （Grant No 0475012） and partially by Technology ＆ Science Foundation of China Academy of Engineering ＆ Physics （Grant No 20040210）.
文摘An analytical scheme on the initial transient process in a simple helical flux compression generator, which includes the distributions of both the magnetic field in the hollow of an armature and the conducting current density in the stator, is developed by means of a diffusion equation. A relationship between frequency of the conducting current, root of the characteristic function of Bessel equation and decay time in the armature is given. The skin depth in the helical stator is calculated and is compared with the approximate one which is widely used in the calculation of magnetic diffusion. Our analytical results are helpful to understanding the mechanism of the loss of magnetic flux in both the armature and stator and to suggesting an optimal design for improving performance of the helical flux compression generator.
