After introducing the theories parabola （FDP）, half-wave-length length, offset and the maximum of acceleration （LCA）, the SI curve, and geometric features of four familiar transition curves （cubic parabola （CP）...After introducing the theories parabola （FDP）, half-wave-length length, offset and the maximum of acceleration （LCA）, the SI curve, and geometric features of four familiar transition curves （cubic parabola （CP）, fifth degree sinusoidal （HS） and sinusoidal （SI）） , these curves are compared under identical conditions of the first derivative of curvature. In terms of the roll acceleration （RA） and the lateral change of in theory, is superior to other transition curves.展开更多
The short secret key characteristic of elliptic curve cryptosystem （ECC） are integrated with the （ t, n ） threshold method to create a practical threshold group signature scheme characterized by simultaneous signi...The short secret key characteristic of elliptic curve cryptosystem （ECC） are integrated with the （ t, n ） threshold method to create a practical threshold group signature scheme characterized by simultaneous signing. The scheme not only meets the requirements of anonymity and traceability of group signature but also can withstand Tseng and Wang＇s conspiracy attack. It allows the group manager to add new members and delete old members according to actual application, while the system parameters have a little change. Cryptanalysis result shows that the scheme is efficient and secure.展开更多
The effect of the fastener＇s failure in a railway track on the dynamic forces produced in the wheel-rail contact is studied using the simulation software VAMPIRE to assess the derailment risk of two different vehicle...The effect of the fastener＇s failure in a railway track on the dynamic forces produced in the wheel-rail contact is studied using the simulation software VAMPIRE to assess the derailment risk of two different vehicles in two curves with distinct characteristics. First, a 3D-FEM model of a real track is constructed, paying special attention to fasteners, and calibrated with displacement data obtained experimentally during a train passage. This numerical model is subsequently used to determine the track vertical and lateral stiffness. This study evidences that although the track can practically lose its lateral stiffness as a consequence of the failure of 7 consecutive fasteners, the vehicle stability would not be necessarily compromised in the flawed zone. Moreover, the results reveal that the uncompensated acceleration and the distance along which the fasteners are failed play an important role in the dynamic behavior of the vehicle-track system, influencing strongly the risk of derailment.展开更多
In this paper an integral transform method is used to analyze the dynamic response of simple supported curved beam under single moving load with constant speed, and some parameters are defined. These parameters, such ...In this paper an integral transform method is used to analyze the dynamic response of simple supported curved beam under single moving load with constant speed, and some parameters are defined. These parameters, such as radius of curvature, ratio of stiffness, velocity, warping stiffness, which may influence the response, are also discussed.展开更多
This paper summarizes the analytical and experimental dynamic analyses carried out to assess the actual dynamic behaviour of a curved cable-stayed bridge,recently erected in the commercial harbour of Porto Marghera ( ...This paper summarizes the analytical and experimental dynamic analyses carried out to assess the actual dynamic behaviour of a curved cable-stayed bridge,recently erected in the commercial harbour of Porto Marghera ( Venice,Italy). Ambient vibration tests were carried out to determine the dynamic characteristics of the bridge and more than 20 modes were identified in the frequency range 0～10Hz. In the theoretical study,a 3D FE model of the bridge was developed using an integrated CAD-FEA approach; subsequently,the information obtained from the field tests,combined with simple manual tuning,provided a linear elastic model,accurately fitting the modal parameters of the bridge in its present condition.展开更多
The basic objects of investigation in this article are nonlinear impulsive dif- ferential equations. The impulsive moments coincide with the moments of meeting of the integral curve and some of the so-called barrier c...The basic objects of investigation in this article are nonlinear impulsive dif- ferential equations. The impulsive moments coincide with the moments of meeting of the integral curve and some of the so-called barrier curves. For such type of equations, suf- ficient conditions are found under which the solutions are continuously dependent on the perturbations with respect to the initial conditions and barrier curves. The results are applied to a mathematical model of population dynamics.展开更多
Path marginal cost （PMC） is the change in totaltravel cost for flow on the network that arises when timedependentpath flow changes by 1 unit. Because it is hardto obtain the marginal cost on all the links, the local...Path marginal cost （PMC） is the change in totaltravel cost for flow on the network that arises when timedependentpath flow changes by 1 unit. Because it is hardto obtain the marginal cost on all the links, the local PMC,considering marginal cost of partial links, is normallycalculated to approximate the global PMC. When analyzingthe marginal cost at a congested diverge intersection, ajump-point phenomenon may occur. It manifests as alikelihood that a vehicle may unsteadily lift up （down） inthe cumulative flow curve of the downstream links. Previously,the jump-point caused delay was ignored whencalculating the local PMC. This article proposes an analyticalmethod to solve this delay which can contribute toobtaining a more accurate local PMC. Next to that, we usea simple case to calculate the previously local PMC and themodified one. The test shows a large gap between them,which means that this delay should not be omitted in thelocal PMC calculation.展开更多
Based on performance data of over 600 wells in 32 large gas fields of different types in China, the correlation is established between per-well average dynamic reserves( G) and average initial absolute open flow poten...Based on performance data of over 600 wells in 32 large gas fields of different types in China, the correlation is established between per-well average dynamic reserves( G) and average initial absolute open flow potential(IAOFq) of each field, and its connotation and applicability are further discussed through theoretical deduction. In log-log plot, G vs. IAOFq exhibit highly dependent linear trend, which implicates the compatibility between G and IAOFq attained through development optimization to reach the balance among annual flow capacity, maximum profits and certain production plateau, that is to match productivity with rate maintenance capacity. The correlation can be used as analogue in new gas field development planning to evaluate the minimum dynamic reserves which meet the requirement of stable and profitable production, and facilitate well pattern arrangement. It can also serve as criteria to appraise the effectiveness and infill drilling potential of well patterns for developed gas fields.展开更多
基金The National Natural Science Foundation of China(No.50878134)the Natural Science Foundation of Hebei Province(No.E2006000394)the Natural Science Foundation of Hebei Education Department(No.2006142)
文摘After introducing the theories parabola （FDP）, half-wave-length length, offset and the maximum of acceleration （LCA）, the SI curve, and geometric features of four familiar transition curves （cubic parabola （CP）, fifth degree sinusoidal （HS） and sinusoidal （SI）） , these curves are compared under identical conditions of the first derivative of curvature. In terms of the roll acceleration （RA） and the lateral change of in theory, is superior to other transition curves.
基金The National Natural Science Foundation of China (No60403027)
文摘The short secret key characteristic of elliptic curve cryptosystem （ECC） are integrated with the （ t, n ） threshold method to create a practical threshold group signature scheme characterized by simultaneous signing. The scheme not only meets the requirements of anonymity and traceability of group signature but also can withstand Tseng and Wang＇s conspiracy attack. It allows the group manager to add new members and delete old members according to actual application, while the system parameters have a little change. Cryptanalysis result shows that the scheme is efficient and secure.
文摘The effect of the fastener＇s failure in a railway track on the dynamic forces produced in the wheel-rail contact is studied using the simulation software VAMPIRE to assess the derailment risk of two different vehicles in two curves with distinct characteristics. First, a 3D-FEM model of a real track is constructed, paying special attention to fasteners, and calibrated with displacement data obtained experimentally during a train passage. This numerical model is subsequently used to determine the track vertical and lateral stiffness. This study evidences that although the track can practically lose its lateral stiffness as a consequence of the failure of 7 consecutive fasteners, the vehicle stability would not be necessarily compromised in the flawed zone. Moreover, the results reveal that the uncompensated acceleration and the distance along which the fasteners are failed play an important role in the dynamic behavior of the vehicle-track system, influencing strongly the risk of derailment.
文摘In this paper an integral transform method is used to analyze the dynamic response of simple supported curved beam under single moving load with constant speed, and some parameters are defined. These parameters, such as radius of curvature, ratio of stiffness, velocity, warping stiffness, which may influence the response, are also discussed.
基金support provided by the Italian Ministry of University and Research,under the grant PRIN 2006
文摘This paper summarizes the analytical and experimental dynamic analyses carried out to assess the actual dynamic behaviour of a curved cable-stayed bridge,recently erected in the commercial harbour of Porto Marghera ( Venice,Italy). Ambient vibration tests were carried out to determine the dynamic characteristics of the bridge and more than 20 modes were identified in the frequency range 0～10Hz. In the theoretical study,a 3D FE model of the bridge was developed using an integrated CAD-FEA approach; subsequently,the information obtained from the field tests,combined with simple manual tuning,provided a linear elastic model,accurately fitting the modal parameters of the bridge in its present condition.
文摘The basic objects of investigation in this article are nonlinear impulsive dif- ferential equations. The impulsive moments coincide with the moments of meeting of the integral curve and some of the so-called barrier curves. For such type of equations, suf- ficient conditions are found under which the solutions are continuously dependent on the perturbations with respect to the initial conditions and barrier curves. The results are applied to a mathematical model of population dynamics.
文摘Path marginal cost （PMC） is the change in totaltravel cost for flow on the network that arises when timedependentpath flow changes by 1 unit. Because it is hardto obtain the marginal cost on all the links, the local PMC,considering marginal cost of partial links, is normallycalculated to approximate the global PMC. When analyzingthe marginal cost at a congested diverge intersection, ajump-point phenomenon may occur. It manifests as alikelihood that a vehicle may unsteadily lift up （down） inthe cumulative flow curve of the downstream links. Previously,the jump-point caused delay was ignored whencalculating the local PMC. This article proposes an analyticalmethod to solve this delay which can contribute toobtaining a more accurate local PMC. Next to that, we usea simple case to calculate the previously local PMC and themodified one. The test shows a large gap between them,which means that this delay should not be omitted in thelocal PMC calculation.
文摘Based on performance data of over 600 wells in 32 large gas fields of different types in China, the correlation is established between per-well average dynamic reserves( G) and average initial absolute open flow potential(IAOFq) of each field, and its connotation and applicability are further discussed through theoretical deduction. In log-log plot, G vs. IAOFq exhibit highly dependent linear trend, which implicates the compatibility between G and IAOFq attained through development optimization to reach the balance among annual flow capacity, maximum profits and certain production plateau, that is to match productivity with rate maintenance capacity. The correlation can be used as analogue in new gas field development planning to evaluate the minimum dynamic reserves which meet the requirement of stable and profitable production, and facilitate well pattern arrangement. It can also serve as criteria to appraise the effectiveness and infill drilling potential of well patterns for developed gas fields.
