An adaptive method of residual life estimation for deteriorated products with two performance characteristics (PCs) was proposed, which was sharply different from existing work that only utilized one-dimensional degra...An adaptive method of residual life estimation for deteriorated products with two performance characteristics (PCs) was proposed, which was sharply different from existing work that only utilized one-dimensional degradation data. Once new degradation information was available, the residual life of the product being monitored could be estimated in an adaptive manner. Here, it was assumed that the degradation of each PC over time was governed by a Wiener degradation process and the dependency between them was characterized by the Frank copula function. A bivariate Wiener process model with measurement errors was used to model the degradation measurements. A two-stage method and the Markov chain Monte Carlo (MCMC) method were combined to estimate the unknown parameters in sequence. Results from a numerical example about fatigue cracks show that the proposed method is valid as the relative error is small.展开更多
We in terms of optical theorem estimate the lifetime of B<SUB>c</SUB> meson with the parameters which are determined by fitting the data for the lifetimes and inclusive semileptonic decays of various B and...We in terms of optical theorem estimate the lifetime of B<SUB>c</SUB> meson with the parameters which are determined by fitting the data for the lifetimes and inclusive semileptonic decays of various B and D mesons. In the estimation, we find that the bound-state effects are important, and take them into account carefully in the framework which attributes the effects to the effective masses of the decay heavy quarks in the inclusive processes. We also find that to B<SUB>c</SUB> lifetime the penguin contribution is enhanced due to possible interference between the penguin and the 'tree part' c<SUB>1</SUB>O<SUB>1</SUB> + c<SUB>2</SUB>O<SUB>2</SUB>.展开更多
Studies to date have failed to consider gage disc cutters’variable cutting depth and the constraints of cutter-head welds,and have ignored the coupling mechanism between the profile of the full-face rock tunnel-borin...Studies to date have failed to consider gage disc cutters’variable cutting depth and the constraints of cutter-head welds,and have ignored the coupling mechanism between the profile of the full-face rock tunnel-boring machine(TBM)cutter-head and the assembled radius layout of the disc cutters.To solve these problems,an adaptive design method for studying cutter layout was proposed.Taking the bearing stress of the outermost gage disc cutter as an index,the profile of the cutter-head was determined.Using a genetic algorithm and based on the principles of equal life and equal wear,the assembled radii of the cutters were optimally designed.Boundary conditions of non-interference between the cutters,manholes,muck buckets and welding lines were given when a star layout pattern was used on cutters.The cutter-head comprehensive evaluation model was established by adopting relative optimization improvement degree of evaluation indices to achieve dimensional consistency.Exemplifying the MB264-311-8030 mm tape TBM cutter-head,the calculations show that compared with the original layout scheme,among the 51 disc cutters,the largest gap of the cutters’assembled radiuses is only 25.8 mm,which is 0.64%of the cutter-head’s radius and is negligible.The cutter-head’s unbalanced radial force decreases by 62.41%,the overturning moment decreases by 33.22%,and the cutter group’s centroid shift increases by only 18.48%.Each index is better than or approximately equal to the original cutter-head layout scheme,and the equivalent stress and deformation are both smaller;these results fully verify the feasibility and effectiveness of the method.展开更多
The Trusted Platform Module (TPM) is a dedicated hardware chip designed to provide a higher level of security for computing platform. All TPM functionalities are implemented in TPM corntrends to achieve specific sec...The Trusted Platform Module (TPM) is a dedicated hardware chip designed to provide a higher level of security for computing platform. All TPM functionalities are implemented in TPM corntrends to achieve specific security goals. We attempt to analyze the security properties of these commands, especially the key management API. Our study utilizes applied pi calculus to forrmlize the commands and determine how their security properties affect TPM key rmnagement. The attacker is assumed to call TPM comrmnds without bounds and without knowing the TPM root key, expecting to obtain or replace the user key. The analysis goal in our study is to guarantee the corre- sponding property of API execution and the integrity of API data. We analyze the security properties of TPM commands with a process reduction method, identify the key-handle hijack attack on a TPM newly created key, and propose reasonable solutions to solve the problem. Then, we conduct an experiment involving a key-handle attack, which suc- cessfully replaces a user key with an attacker's key using lmlicious TPM software. This paper discloses the weakness of the relationship between the key handle and the key object. After the TPM software stack is compromised, the attacker can hunch a keyhandle attack to obtain the user key and even break into the whole storage tree of user keys.展开更多
To quantify the energy consumption in the process of production, transportation and processing of energy carriers, the life cycle of building energy used can be divided into two phases: on-site phase and embodied pha...To quantify the energy consumption in the process of production, transportation and processing of energy carriers, the life cycle of building energy used can be divided into two phases: on-site phase and embodied phase. As for the embodied phase, with the data in existing statistic yearbook, the consumption items of energy production and transportation were investigated. And based on the life cycle theory, an embodied coefficient of energy carriers was proposed to quantify the embodied energy consumption. Moreover, a calculation method for the embodied coefficient of energy carriers was deduced using Leontief inverse matrix based on the existing data sources. With relevant data of 2005-2007 in China, the embodied coefficients in 2005-2007 were obtained, in which the values for natural gas and thermal power are around 1.3 and 3. l, respectively; while they are 1.03-1.08 for other selected energy carriers. In addition, it is also found that the consumption in the production and processing accounts for more than 75%.展开更多
In order to mitigate vortex-induced vibration (VIV) of marine risers, especially to eliminate the phenomenon of frequency 'lock-in', a new suppression device of crescent-shaped flow spoiler was designed with s...In order to mitigate vortex-induced vibration (VIV) of marine risers, especially to eliminate the phenomenon of frequency 'lock-in', a new suppression device of crescent-shaped flow spoiler was designed with seven different layout schemes. VIV model tests with six flow levels were conducted in a large wind-wave-current flume. In all cases, vibration responses in both in-line and cross-flow cases were measured. With the installation of suppression devices vibration frequency evolution of a riser was analyzed by Morlet wavelet transform. The principle of VIV suppression was interpreted through vibration characteristics. Fatigue life of the riser was calculated by the Palmgren-Miner rule. Compared with a bare riser, vibration of an outfitted riser with suppression devices disturbed the steady flow, the vibration amplitudes in the two flow directions were reduced, and the riser fatigue life was improved.展开更多
In rare cases rolling bearings fail by WEC (white etching crack) damage before reaching their calculated rating life, if so called additional loads are applied on the bearing in addition to the normal Hertzian stre...In rare cases rolling bearings fail by WEC (white etching crack) damage before reaching their calculated rating life, if so called additional loads are applied on the bearing in addition to the normal Hertzian stress (PHz). A number of additional loads have been identified by means of tests with rolling bearings. These can be small direct currents as a result of electrostatic charge or large alternating currents from inverter-fed drives that unintentionally flow through the bearing. WEC damages can also be initiated by a pure mechanical additional load which is dependent on factors including the bearing kinematics but also on the dynamics of the drive train. The current state of knowledge on this subject is presented and taken as the basis for developing a hypothesis on the WEC damage mechanism. If load situations critical for WEC cannot be avoided, the risk of WEC can be considerably reduced by the selection of suitable materials and coatings as well as, in some cases, of suitable lubricants.展开更多
The Korea Water Resources Corporation (K-Water) has encountered four problems during the management of water resources of approximately 1,300 buildings spread throughout the country-degradation, budget constraints, ...The Korea Water Resources Corporation (K-Water) has encountered four problems during the management of water resources of approximately 1,300 buildings spread throughout the country-degradation, budget constraints, lack of standards, and lack of planning. In this study, we have developed a mechanism for collecting, maintaining, and analyzing ground data for repair and replacement works. Our BMS (building maintenance system) uses the recorded repair and replacement work histories and calculates the life cycle costs of the related items. Further, it enables the performance of repair and replacement tasks through an integrated approach aimed at preventive maintenance. In this manner, the BMS is expected to maximize the efficiency of the formulation of prevention and maintenance work plans, monitoring of work histories, predictions of future tasks from the analyses of repair and replacement histories, and performance of LCC (life cycle cost) calculations. Reliable maintenance of national properties can thus be achieved by using the BMS, which promotes reasonable and efficient repair and replacement activities.展开更多
The study of finite nuclei containing antibaryon(s) in addition to nucleons is an interesting topic in nuclear physics. The calculation of the lifetime of an antibaryon embedded in a nucleus was performed in the fra...The study of finite nuclei containing antibaryon(s) in addition to nucleons is an interesting topic in nuclear physics. The calculation of the lifetime of an antibaryon embedded in a nucleus was performed in the framework of the standard quantum field theory. It was shown that the annihilation probability of the antibaryon in nuclei is strongly dependent on the effective masses of mesons involved in the annihilation channels. The contribution of the Dirac sea to the annihilation probability makes the lifetime of the antibaryon short. If the Dirac sea effect is neglected, the lifetime of the bound antibaryon tends to be longer with the nuclear density increasing. Particularly, when the nuclear density is larger than a critical value, the antibaryon may exist stably in a nucleus.展开更多
The technological revolution moves recording and analysis activities that were traditionally professional performance lines of activities focused to high operational content, but now are being met largely by integrate...The technological revolution moves recording and analysis activities that were traditionally professional performance lines of activities focused to high operational content, but now are being met largely by integrated computer systems. The scientific and technological progress, growth and internationalization of markets, processors are processes in which the accounting profession plays a leading role. This paper aims to review the interrelated subjects in the era of public accounting and also its background comes as we展开更多
Large-module rack of the Three Gorges shiplift is manufactured by casting and machining, which is unable to avoid slag inclusions and surface cracks. To ensure its safety in the future service, studying on crack propa...Large-module rack of the Three Gorges shiplift is manufactured by casting and machining, which is unable to avoid slag inclusions and surface cracks. To ensure its safety in the future service, studying on crack propagation rule and the residual life estimation method of large-module rack is of great significance. The possible crack distribution forms of the rack in the Three Gorges shiplift were studied. By applying moving load on the model in FRANC3 D and ANSYS, quantitative analyses of interference effects on double cracks in both collinear and offset conditions were conducted. The variation rule of the stress intensity factor(SIF) influence factor, RK, of double collinear cracks changing with crack spacing ratio, RS, was researched. The horizontal and vertical crack spacing threshold of double cracks within the design life of the shiplift were obtained, which are 24 and 4 times as large as half of initial crack length, c0, respectively. The crack growth rates along the length and depth directions in the process of coalescence on double collinear cracks were also studied.展开更多
Micro porosity in aluminum alloys may contribute to fatigue life degradation, which can largely limit the application of alloys. Therefore, the fatigue life of a commercial 7050-T7451 thick plate and an experimental p...Micro porosity in aluminum alloys may contribute to fatigue life degradation, which can largely limit the application of alloys. Therefore, the fatigue life of a commercial 7050-T7451 thick plate and an experimental plate with different porosities was compared in this study. The X-ray computed tomography(XCT) was utilized to characterize the size, number density and spatial distribution of porosity inside various samples, and the fracture surface of fatigued specimens was compared by using scanning electron microscope(SEM). The results showed that the fatigue cracks prefer to initiate from constituent particles in the commercial alloy. Whereas the micro porosity is the predominant site for crack nucleation and subsequent failure in the experimental one. The presence of micro porosity in experimental7050-T7451 thick plate may reduce the fatigue life by an order of magnitude or more compared with the defect-free alloy. The pores close to sample surface are the main fatigue crack initiation site, among which larger and deeper pore leads to a shorter fatigue life. The crack initiation is also affected by the pore geometry and direction. Besides, the overall porosity inside the bulk can affect the crack propagation during fatigue tests.展开更多
The paper analyzes John Presper Eckert and John William Mauchly's endeavours to design, sell, and build the revolutionary new technology of the first-large and commercial computers. It discusses how Eckert and Mauchl...The paper analyzes John Presper Eckert and John William Mauchly's endeavours to design, sell, and build the revolutionary new technology of the first-large and commercial computers. It discusses how Eckert and Mauchly's conceptualization of the computer grew out of their Electronic Numerical Integrator and Calculator (ENIAC) and Electronic Discrete Variable Automatic Computer (EDVAC) projects at University of Pennsylvania. They incorporated their own business to gain profit from production and attain the freedom needed to develop their revolutionary new computer technology through a series of small and separate computer projects with private and government customers. The paper approaches innovation as a chaotic process and uses uncertainty to conceptualize the basic relations between actors and organizations.展开更多
Recently, the frequent extreme natural disasters made enormous damage to the electric grid leading to blackouts. The lifeline system aiming at providing continuous power supply for the important load in extreme natura...Recently, the frequent extreme natural disasters made enormous damage to the electric grid leading to blackouts. The lifeline system aiming at providing continuous power supply for the important load in extreme natural disasters was designed in that condition. In this paper, a developed model for planning of the transformer substation in lifeline system which considered the effect of existing transformer substations, the motivated areas and punishment areas was proposed. The Hopfield NN (neural network) was adopted to solve the feeders and the PSO (particle swarm optimization) was adopted to new the locations of the transformer substations based on the feeders. The planning result not only took fully use of the existing substation but also got the suitable location for new construction which was satisfactory.展开更多
A computer analysis of solar heating has been performed for Palestine. Results are presented for a prototype building using either fuel oil or gas under different heating loads in three climatic regions (Jordan valle...A computer analysis of solar heating has been performed for Palestine. Results are presented for a prototype building using either fuel oil or gas under different heating loads in three climatic regions (Jordan valley, coastal, and hilly). Cumulative cost flows are compared for the life-cycle present value technique. Optimum design magnitudes are determined for maximum life-cycle savings. The payback period for capital invested in a solar system, and total savings are found for the optimum conditions. Variations of system performance are estimated. The effects of collector slope, proportionate storage tank volume, heat-exchanger parameters, and the design load on system performance are studied. Finally the economics of solar heating in Palestine are discussed and recommendations are made for increased utilization of solar energy.展开更多
For an energy-efficient induction machine, the life-cycle cost (LCC) usually is the most important index to the consumer. With this target, the optimization design of a motor is a complex nonlinear problem with constr...For an energy-efficient induction machine, the life-cycle cost (LCC) usually is the most important index to the consumer. With this target, the optimization design of a motor is a complex nonlinear problem with constraints. To solve the problem, the authors introduce a united random algorithm. At first, the problem is divided into two parts, the optimal rotor slots and the optimization of other dimensions. Before optimizing the rotor slots with genetic algorithm ( GA), the second part is solved with TABU algorithm to simplify the problem. The numerical results showed that this method is better than the method using a traditional algorithm.展开更多
In case of restrictive defense budget financing, efficient and effective use of funds is now more than ever becoming a crucial question in functioning of the Ministry of Defense and Serbian Armed Forces (MoD and SAF...In case of restrictive defense budget financing, efficient and effective use of funds is now more than ever becoming a crucial question in functioning of the Ministry of Defense and Serbian Armed Forces (MoD and SAF). Any investment in acquisition of arms and military equipment (AME) due to financial significance does not allow mistakes in decision making. Qualitative analysis of cost of assets through the entire programmed lifecycle is a complex multi-disciplinary and multi-criteria problem whose solving requires application of the model multi-criteria optimization. In our operational practice thus far, solving the said problems there wasn't enough the model multi-criteria optimization so the optimal results were lacking. In this paper investment process of AME in the MoD and SAF was analyzed, from the point of cost treatment in the process, its flaws have been pointed out and a more comprehensive - integrated approach has been suggested.展开更多
Target tracking in wireless sensor network usually schedules a subset of sensor nodes to constitute a tasking cluster to collaboratively track a target.For the goals of saving energy consumption,prolonging network lif...Target tracking in wireless sensor network usually schedules a subset of sensor nodes to constitute a tasking cluster to collaboratively track a target.For the goals of saving energy consumption,prolonging network lifetime and improving tracking accuracy,sensor node scheduling for target tracking is indeed a multi-objective optimization problem.In this paper,a multi-objective optimization sensor node scheduling algorithm is proposed.It employs the unscented Kalman filtering algorithm for target state estimation and establishes tracking accuracy index,predicts the energy consumption of candidate sensor nodes,analyzes the relationship between network lifetime and remaining energy balance so as to construct energy efficiency index.Simulation results show that,compared with the existing sensor node scheduling,our proposed algorithm can achieve superior tracking accuracy and energy efficiency.展开更多
Abstract In the present paper, some basic properties of MP filters of Ro algebra M are investigated. It is proved that(FMP(M),包含,′∧^-∨^-,{1},M)is a bounded distributive lattice by introducing the negation ope...Abstract In the present paper, some basic properties of MP filters of Ro algebra M are investigated. It is proved that(FMP(M),包含,′∧^-∨^-,{1},M)is a bounded distributive lattice by introducing the negation operator ′, the meet operator ∧^-, the join operator ∨^- and the implicati on operator → on the set FMP(M) of all MP filters of M. Moreover, some conditions under which (FMP(M),包含,′∨^-,→{1},M)is an Ro algebra are given. And the relationship between prime elements of FMP (M) and prime filters of M is studied. Finally, some equivalent characterizations of prime elements of .FMP (M) are obtained.展开更多
基金Project(60904002)supported by the National Natural Science Foundation of China
文摘An adaptive method of residual life estimation for deteriorated products with two performance characteristics (PCs) was proposed, which was sharply different from existing work that only utilized one-dimensional degradation data. Once new degradation information was available, the residual life of the product being monitored could be estimated in an adaptive manner. Here, it was assumed that the degradation of each PC over time was governed by a Wiener degradation process and the dependency between them was characterized by the Frank copula function. A bivariate Wiener process model with measurement errors was used to model the degradation measurements. A two-stage method and the Markov chain Monte Carlo (MCMC) method were combined to estimate the unknown parameters in sequence. Results from a numerical example about fatigue cracks show that the proposed method is valid as the relative error is small.
文摘We in terms of optical theorem estimate the lifetime of B<SUB>c</SUB> meson with the parameters which are determined by fitting the data for the lifetimes and inclusive semileptonic decays of various B and D mesons. In the estimation, we find that the bound-state effects are important, and take them into account carefully in the framework which attributes the effects to the effective masses of the decay heavy quarks in the inclusive processes. We also find that to B<SUB>c</SUB> lifetime the penguin contribution is enhanced due to possible interference between the penguin and the 'tree part' c<SUB>1</SUB>O<SUB>1</SUB> + c<SUB>2</SUB>O<SUB>2</SUB>.
基金Projects(51275339,51575379,51675374)supported by the National Natural Science Foundation of ChinaProject(2013CB035402)supported by the National Hi-tech Research and Development Program of China
文摘Studies to date have failed to consider gage disc cutters’variable cutting depth and the constraints of cutter-head welds,and have ignored the coupling mechanism between the profile of the full-face rock tunnel-boring machine(TBM)cutter-head and the assembled radius layout of the disc cutters.To solve these problems,an adaptive design method for studying cutter layout was proposed.Taking the bearing stress of the outermost gage disc cutter as an index,the profile of the cutter-head was determined.Using a genetic algorithm and based on the principles of equal life and equal wear,the assembled radii of the cutters were optimally designed.Boundary conditions of non-interference between the cutters,manholes,muck buckets and welding lines were given when a star layout pattern was used on cutters.The cutter-head comprehensive evaluation model was established by adopting relative optimization improvement degree of evaluation indices to achieve dimensional consistency.Exemplifying the MB264-311-8030 mm tape TBM cutter-head,the calculations show that compared with the original layout scheme,among the 51 disc cutters,the largest gap of the cutters’assembled radiuses is only 25.8 mm,which is 0.64%of the cutter-head’s radius and is negligible.The cutter-head’s unbalanced radial force decreases by 62.41%,the overturning moment decreases by 33.22%,and the cutter group’s centroid shift increases by only 18.48%.Each index is better than or approximately equal to the original cutter-head layout scheme,and the equivalent stress and deformation are both smaller;these results fully verify the feasibility and effectiveness of the method.
基金This paper was supported by the National Natural Science Foundation of China under Grants No.91118006, No. 61202414 the Knowledge Innovation Project of Chinese Academy of Science under Grant No. ISCAS2009-DR14.
文摘The Trusted Platform Module (TPM) is a dedicated hardware chip designed to provide a higher level of security for computing platform. All TPM functionalities are implemented in TPM corntrends to achieve specific security goals. We attempt to analyze the security properties of these commands, especially the key management API. Our study utilizes applied pi calculus to forrmlize the commands and determine how their security properties affect TPM key rmnagement. The attacker is assumed to call TPM comrmnds without bounds and without knowing the TPM root key, expecting to obtain or replace the user key. The analysis goal in our study is to guarantee the corre- sponding property of API execution and the integrity of API data. We analyze the security properties of TPM commands with a process reduction method, identify the key-handle hijack attack on a TPM newly created key, and propose reasonable solutions to solve the problem. Then, we conduct an experiment involving a key-handle attack, which suc- cessfully replaces a user key with an attacker's key using lmlicious TPM software. This paper discloses the weakness of the relationship between the key handle and the key object. After the TPM software stack is compromised, the attacker can hunch a keyhandle attack to obtain the user key and even break into the whole storage tree of user keys.
基金Project(CDJZR10210009) supported by Central College General Fund for Natural Science of Chongqing City,China
文摘To quantify the energy consumption in the process of production, transportation and processing of energy carriers, the life cycle of building energy used can be divided into two phases: on-site phase and embodied phase. As for the embodied phase, with the data in existing statistic yearbook, the consumption items of energy production and transportation were investigated. And based on the life cycle theory, an embodied coefficient of energy carriers was proposed to quantify the embodied energy consumption. Moreover, a calculation method for the embodied coefficient of energy carriers was deduced using Leontief inverse matrix based on the existing data sources. With relevant data of 2005-2007 in China, the embodied coefficients in 2005-2007 were obtained, in which the values for natural gas and thermal power are around 1.3 and 3. l, respectively; while they are 1.03-1.08 for other selected energy carriers. In addition, it is also found that the consumption in the production and processing accounts for more than 75%.
基金financially supported by the High Technology Research and Development Program of China (863 Program, Grant No. 2010AA09Z303)
文摘In order to mitigate vortex-induced vibration (VIV) of marine risers, especially to eliminate the phenomenon of frequency 'lock-in', a new suppression device of crescent-shaped flow spoiler was designed with seven different layout schemes. VIV model tests with six flow levels were conducted in a large wind-wave-current flume. In all cases, vibration responses in both in-line and cross-flow cases were measured. With the installation of suppression devices vibration frequency evolution of a riser was analyzed by Morlet wavelet transform. The principle of VIV suppression was interpreted through vibration characteristics. Fatigue life of the riser was calculated by the Palmgren-Miner rule. Compared with a bare riser, vibration of an outfitted riser with suppression devices disturbed the steady flow, the vibration amplitudes in the two flow directions were reduced, and the riser fatigue life was improved.
文摘In rare cases rolling bearings fail by WEC (white etching crack) damage before reaching their calculated rating life, if so called additional loads are applied on the bearing in addition to the normal Hertzian stress (PHz). A number of additional loads have been identified by means of tests with rolling bearings. These can be small direct currents as a result of electrostatic charge or large alternating currents from inverter-fed drives that unintentionally flow through the bearing. WEC damages can also be initiated by a pure mechanical additional load which is dependent on factors including the bearing kinematics but also on the dynamics of the drive train. The current state of knowledge on this subject is presented and taken as the basis for developing a hypothesis on the WEC damage mechanism. If load situations critical for WEC cannot be avoided, the risk of WEC can be considerably reduced by the selection of suitable materials and coatings as well as, in some cases, of suitable lubricants.
文摘The Korea Water Resources Corporation (K-Water) has encountered four problems during the management of water resources of approximately 1,300 buildings spread throughout the country-degradation, budget constraints, lack of standards, and lack of planning. In this study, we have developed a mechanism for collecting, maintaining, and analyzing ground data for repair and replacement works. Our BMS (building maintenance system) uses the recorded repair and replacement work histories and calculates the life cycle costs of the related items. Further, it enables the performance of repair and replacement tasks through an integrated approach aimed at preventive maintenance. In this manner, the BMS is expected to maximize the efficiency of the formulation of prevention and maintenance work plans, monitoring of work histories, predictions of future tasks from the analyses of repair and replacement histories, and performance of LCC (life cycle cost) calculations. Reliable maintenance of national properties can thus be achieved by using the BMS, which promotes reasonable and efficient repair and replacement activities.
基金Supported by National Natural Science Foundation of China under Grant No.10775059Specialized Research Fand for the Doctoral Program of Higher Education of China under Grant No.20070183133
文摘The study of finite nuclei containing antibaryon(s) in addition to nucleons is an interesting topic in nuclear physics. The calculation of the lifetime of an antibaryon embedded in a nucleus was performed in the framework of the standard quantum field theory. It was shown that the annihilation probability of the antibaryon in nuclei is strongly dependent on the effective masses of mesons involved in the annihilation channels. The contribution of the Dirac sea to the annihilation probability makes the lifetime of the antibaryon short. If the Dirac sea effect is neglected, the lifetime of the bound antibaryon tends to be longer with the nuclear density increasing. Particularly, when the nuclear density is larger than a critical value, the antibaryon may exist stably in a nucleus.
文摘The technological revolution moves recording and analysis activities that were traditionally professional performance lines of activities focused to high operational content, but now are being met largely by integrated computer systems. The scientific and technological progress, growth and internationalization of markets, processors are processes in which the accounting profession plays a leading role. This paper aims to review the interrelated subjects in the era of public accounting and also its background comes as we
基金Project(0722018)supported by the China Three Gorges CorporationProject(2012KJX01)supported by the Hubei Key Laboratory of Hydroelectric Machinery Design&Maintenance,China
文摘Large-module rack of the Three Gorges shiplift is manufactured by casting and machining, which is unable to avoid slag inclusions and surface cracks. To ensure its safety in the future service, studying on crack propagation rule and the residual life estimation method of large-module rack is of great significance. The possible crack distribution forms of the rack in the Three Gorges shiplift were studied. By applying moving load on the model in FRANC3 D and ANSYS, quantitative analyses of interference effects on double cracks in both collinear and offset conditions were conducted. The variation rule of the stress intensity factor(SIF) influence factor, RK, of double collinear cracks changing with crack spacing ratio, RS, was researched. The horizontal and vertical crack spacing threshold of double cracks within the design life of the shiplift were obtained, which are 24 and 4 times as large as half of initial crack length, c0, respectively. The crack growth rates along the length and depth directions in the process of coalescence on double collinear cracks were also studied.
基金Project(2019KJ2X08-4) supported by Chinalco Technology Development Project Fund,China。
文摘Micro porosity in aluminum alloys may contribute to fatigue life degradation, which can largely limit the application of alloys. Therefore, the fatigue life of a commercial 7050-T7451 thick plate and an experimental plate with different porosities was compared in this study. The X-ray computed tomography(XCT) was utilized to characterize the size, number density and spatial distribution of porosity inside various samples, and the fracture surface of fatigued specimens was compared by using scanning electron microscope(SEM). The results showed that the fatigue cracks prefer to initiate from constituent particles in the commercial alloy. Whereas the micro porosity is the predominant site for crack nucleation and subsequent failure in the experimental one. The presence of micro porosity in experimental7050-T7451 thick plate may reduce the fatigue life by an order of magnitude or more compared with the defect-free alloy. The pores close to sample surface are the main fatigue crack initiation site, among which larger and deeper pore leads to a shorter fatigue life. The crack initiation is also affected by the pore geometry and direction. Besides, the overall porosity inside the bulk can affect the crack propagation during fatigue tests.
文摘The paper analyzes John Presper Eckert and John William Mauchly's endeavours to design, sell, and build the revolutionary new technology of the first-large and commercial computers. It discusses how Eckert and Mauchly's conceptualization of the computer grew out of their Electronic Numerical Integrator and Calculator (ENIAC) and Electronic Discrete Variable Automatic Computer (EDVAC) projects at University of Pennsylvania. They incorporated their own business to gain profit from production and attain the freedom needed to develop their revolutionary new computer technology through a series of small and separate computer projects with private and government customers. The paper approaches innovation as a chaotic process and uses uncertainty to conceptualize the basic relations between actors and organizations.
文摘Recently, the frequent extreme natural disasters made enormous damage to the electric grid leading to blackouts. The lifeline system aiming at providing continuous power supply for the important load in extreme natural disasters was designed in that condition. In this paper, a developed model for planning of the transformer substation in lifeline system which considered the effect of existing transformer substations, the motivated areas and punishment areas was proposed. The Hopfield NN (neural network) was adopted to solve the feeders and the PSO (particle swarm optimization) was adopted to new the locations of the transformer substations based on the feeders. The planning result not only took fully use of the existing substation but also got the suitable location for new construction which was satisfactory.
文摘A computer analysis of solar heating has been performed for Palestine. Results are presented for a prototype building using either fuel oil or gas under different heating loads in three climatic regions (Jordan valley, coastal, and hilly). Cumulative cost flows are compared for the life-cycle present value technique. Optimum design magnitudes are determined for maximum life-cycle savings. The payback period for capital invested in a solar system, and total savings are found for the optimum conditions. Variations of system performance are estimated. The effects of collector slope, proportionate storage tank volume, heat-exchanger parameters, and the design load on system performance are studied. Finally the economics of solar heating in Palestine are discussed and recommendations are made for increased utilization of solar energy.
文摘For an energy-efficient induction machine, the life-cycle cost (LCC) usually is the most important index to the consumer. With this target, the optimization design of a motor is a complex nonlinear problem with constraints. To solve the problem, the authors introduce a united random algorithm. At first, the problem is divided into two parts, the optimal rotor slots and the optimization of other dimensions. Before optimizing the rotor slots with genetic algorithm ( GA), the second part is solved with TABU algorithm to simplify the problem. The numerical results showed that this method is better than the method using a traditional algorithm.
文摘In case of restrictive defense budget financing, efficient and effective use of funds is now more than ever becoming a crucial question in functioning of the Ministry of Defense and Serbian Armed Forces (MoD and SAF). Any investment in acquisition of arms and military equipment (AME) due to financial significance does not allow mistakes in decision making. Qualitative analysis of cost of assets through the entire programmed lifecycle is a complex multi-disciplinary and multi-criteria problem whose solving requires application of the model multi-criteria optimization. In our operational practice thus far, solving the said problems there wasn't enough the model multi-criteria optimization so the optimal results were lacking. In this paper investment process of AME in the MoD and SAF was analyzed, from the point of cost treatment in the process, its flaws have been pointed out and a more comprehensive - integrated approach has been suggested.
基金Supported by the National Natural Science Foundation of China(No.90820302,60805027)the Research Fund for Doctoral Program of Higher Education(No.200805330005)the Academician Foundation of Hunan(No.2009FJ4030)
文摘Target tracking in wireless sensor network usually schedules a subset of sensor nodes to constitute a tasking cluster to collaboratively track a target.For the goals of saving energy consumption,prolonging network lifetime and improving tracking accuracy,sensor node scheduling for target tracking is indeed a multi-objective optimization problem.In this paper,a multi-objective optimization sensor node scheduling algorithm is proposed.It employs the unscented Kalman filtering algorithm for target state estimation and establishes tracking accuracy index,predicts the energy consumption of candidate sensor nodes,analyzes the relationship between network lifetime and remaining energy balance so as to construct energy efficiency index.Simulation results show that,compared with the existing sensor node scheduling,our proposed algorithm can achieve superior tracking accuracy and energy efficiency.
文摘Abstract In the present paper, some basic properties of MP filters of Ro algebra M are investigated. It is proved that(FMP(M),包含,′∧^-∨^-,{1},M)is a bounded distributive lattice by introducing the negation operator ′, the meet operator ∧^-, the join operator ∨^- and the implicati on operator → on the set FMP(M) of all MP filters of M. Moreover, some conditions under which (FMP(M),包含,′∨^-,→{1},M)is an Ro algebra are given. And the relationship between prime elements of FMP (M) and prime filters of M is studied. Finally, some equivalent characterizations of prime elements of .FMP (M) are obtained.