Lazy loading algorithm for traffic assignment of road networks under fixed charge condition

The measures of path charge are important considerations in traffic assignment of road networks. Factors, such as travel time, fixed charge and traffic congestion which affect road users＇ choices of trip paths, are analyzed. Travelers usually decide their trip paths based on their personal habits, preferences and the information at hand. By considering both deterministic and stochastic factors which affect the value of time （VOT） during the process of path choosing, a variational inequality model is proposed to describe the problem of traffic assignment. A lazy loading algorithm for traffic assignment is designed to solve the proposed model, and the calculation steps are given. Numerical experiment results show that compared with the all-or-nothing assignment, the proposed model and the algorithm can provide more optimal traffic assignments for road networks. The results of this study can be used to optimize traffic planning and management.

Seismic response of a typical fixed platform foundation under earthquake loading

Offshore platforms in seismically active areas should be designed to service severe earthquake excitations with no global structural failure. This paper summarizes the dynamic analysis of a typical fixed platform under the earthquake loading in the seismically active area. The dynamic analysis includes interpretation of dynamic design parameters based on the available site-specific data,together with foundation design recommendations for earthquake loading conditions,which include free-field site response analyses,liquefaction analyses and soil-pile interaction analyses.

Time-and Frequency-Domain Analysis of Ice-Induced Displacement Responses Offshore Fixed Platforms

On the basis of ice- induced forced vibration model, ice- induced displacement responses of offshore fixed platforms are investigated in both time domain and frequency domain. The relationships of ice-induced displacement responses with ice breaking modes, ice acting directions and platform structures are analyzed and determined. The results lead to an important conclusion obtained for the first time that ice breaking frequency and the natural frequency of the first mode of the platform are the two main factors that dominate the degree of vibration. The present work provides a firm basis for both design and operation of fixed platforms against ice loading.

Study and Commercial Application of Graded Optimization of Catalysts for Fixed Bed Residue Upgrading Unit

The SHIFT-G technology of inverse catalyst loading is used to optimize the catalyst grading in the residue hydrotreating unit. The results, taken from pilot tests and commercial units, have showed that the optimized catalyst grading system can reasonably distribute the reaction load, effectively improve the prop- erties of hydrotreated products, prolong the operating cycle and promote economic benefits.

Mechanical analysis of fixed geosynthetic technique of GRPS embankment

To overcome the deficiencies of conventional geosynthetic-reinforced and pile-supported (GRPS) embankment, a new improvement technique, fixed geosynthetic technique of GRPS embankment (FGT embankment), was developed and introduced. Based on the discussion about the load transfer mechanism of FGT embankment, a simplified check method of the requirement of geosynthetic tensile strength and a mechanical model of the FGT embankment were proposed. Two conditions, the pile cap and pile beam conditions are considered in the mechanical model. The finite difference method is used to solve the mechanical model owing to the complexity of the differential equations and the soil strata. Then, the numerical procedure is programmed. Finally, a field test is conducted to verify the mechanical model and the calculated results are in good agreement with field measured data.

Flexible Load Participation in Peaking Shaving and Valley Filling Based on Dynamic Price Incentives

Considering the widening of the peak-valley difference in the power grid and the difficulty of the existing fixed time-of-use electricity price mechanism in meeting the energy demand of heterogeneous users at various moments or motivating users,the design of a reasonable dynamic pricing mechanism to actively engage users in demand response becomes imperative for power grid companies.For this purpose,a power grid-flexible load bilevel model is constructed based on dynamic pricing,where the leader is the dispatching center and the lower-level flexible load acts as the follower.Initially,an upper-level day-ahead dispatching model for the power grid is established,considering the lowest power grid dispatching cost as the objective function and incorporating the power grid-side constraints.Then,the lower level comprehensively considers the load characteristics of industrial load,energy storage,and data centers,and then establishes a lower-level flexible load operation model with the lowest user power-consuming cost as the objective function.Finally,the proposed method is validated using the IEEE-118 system,and the findings indicate that the dynamic pricing mechanism for peaking shaving and valley filling can effectively guide users to respond actively,thereby reducing the peak-valley difference and decreasing users’purchasing costs.

Load-redistribution strategy based on time-varying load against cascading failure of complex network

Cascading failure can cause great damage to complex networks, so it is of great significance to improve the network robustness against cascading failure. Many previous existing works on load-redistribution strategies require global information, which is not suitable for large scale networks, and some strategies based on local information assume that the load of a node is always its initial load before the network is attacked, and the load of the failure node is redistributed to its neighbors according to their initial load or initial residual capacity. This paper proposes a new load-redistribution strategy based on local information considering an ever-changing load. It redistributes the loads of the failure node to its nearest neighbors according to their current residual capacity, which makes full use of the residual capacity of the network. Experiments are conducted on two typical networks and two real networks, and the experimental results show that the new load-redistribution strategy can reduce the size of cascading failure efficiently.

Dynamic load sharing characteristics and sun gear radial orbits of double-row planetary gear train

A new non-linear bending-torsional coupled model for double-row planetary gear set was proposed, and planet's eccentricity error, static transmission error, and time-varying meshing stiffness were taken into consideration. The solution of differential governing equation of motion is determined by applying the Fourier series method. The behaviors of dynamic load sharing characteristics affected by the system parameters including gear eccentricities error, ring gear's supporting stiffness, planet's bearing stiffness, torsional stiffness of first stage carrier and input rotation rate were investigated qualitatively and systematically, and sun gear radial orbits at first and second stage were explored as well. Some theoretical results are summarized as guidelines for further research and design of double-row planetary gear train at last.

Combined effects of axial load and temperature on finite deformation of incompressible thermo-hyperelastic cylinder

A finite deformation problem is examined for a cylinder composed of a class of incompressible thermo-hyperelastic Mooney-Rivlin materials under an equal axial load at its two fixed ends and a temperature field at its lateral boundary. Firstly, a thermomechanical coupling term is taken into account in the strain energy density function, and a governing equation of the problem is obtained. Secondly, an implicit analytical solution is derived by using the incompressibility and the boundary conditions. Significantly, numerical examples show that the middle portion of the cylinder undergoes almost a uniform radial deformation. However, the deformation near the two ends varies remarkably along the axial direction for relatively large axial loads. In addition, the rising temperature can increase the deformation of structures, and its influence is linear approximately. Specially,in the case of tensile load, the jump increase of the axial deformation may occur.

Simultaneous resonance of an axially moving ferromagnetic thin plate under a line load in a time-varying magnetic field

In this paper,the simultaneous resonance of a ferromagnetic thin plate in a time-varying magnetic field,having axial speed and being subjected to a periodic line load,is studied.Based on the large deflection theory of thin plates and electromagnetic field theory,the nonlinear vibration differential equation of the plate is obtained by using the Hamilton′s principle and the Galerkin method.Then the boundary condition in which the longer opposite sides are clamped and hinged is considered.The dimensionless nonlinear differential equations are solved by using the method of multiple scales,and the analytical solution is given.In addition,the stability analysis is also carried out by using Lyapunov stability theory.Through numerical analysis,the variation curves of system resonance amplitude with frequency tuning parameter,magnetic field strength and external excitation amplitude are obtained.Different parameters that have significant effects on the response of the system,such as the thickness,the axial velocity,the magnetic field intensity,the position,and the frequency of external excitation,are considered and analyzed.The results show that the system has multiple solution regions and obvious nonlinear coupled characteristics.

Dynamic load sharing behavior of transverse-torsional coupled planetary gear train with multiple clearances

A new nonlinear transverse-torsional coupled model with backlash and bearing clearance was proposed for planetary gear set. Meanwhile, sun gear and planet's eccentricity errors, static transmission error, and time-varying meshing stiffness were taken into consideration. The differential governing equations of motion were solved by employing variable step-size Rung-Kutta numerical integration method. The behavior of dynamic load sharing characteristics affected by the system parameters including input rate, sun gear's supporting stiffness and eccentricity error, planet's eccentricity error, sun gear's bearing clearance, backlashes of sun-planet and planet-ring meshes were investigated qualitatively and systematically. Some theoretical results are summarized at last which extend the current understanding of the dynamic load sharing behavior of planet gear train, enrich the related literature and provide references for the design of planetary gear train.

Distortionless Lossy Transmission Lines Terminated by in Series Connected <i>RCL</i>-Loads

The paper deals with a lossy transmission line terminated at both ends by non-linear RCL elements. The mixed problem for the hyperbolic system, describing the transmission line, to an initial value problem for a neutral equation is reduced. Sufficient conditions for the existence and uniqueness of periodic regimes are formulated. The proof is based on the finding out of suitable operator whose fixed point is a periodic solution of the neutral equation. The method has a good rate of convergence of the successive approximations even for high frequencies.

Load distribution of involute gears along time-varying contact line

Base on the theory of energy minimization, a numerical algorithm is established to calculate load distribution, and the relationship curve of spur gear load distribution is obtained, and the load distribution ratio changes from 033 to 067 in double contact zone. This theory is adopted to compute the load distribution of helical gear along time-varying contact line, and the load distribution varies with the instantaneous position of the meshing point and the length of contact line, and the maximum value of load appears at the pitch point. Compared with the load distribution results, the helical gear changes more smoothly than spur gear. The load distribution provides a basis for calculate tooth bending deformation and critical stress.

Dynamics of a Dual Power-split Transmission Based on Loaded Tooth Contact Analysis

In order to implement the dynamic characteristic of a dual power-split transmission, a dynamic me- chanics model is built. Firstly, according to the method of theoretical analysis of the tooth contact analysis （TCA） and loaded tooth contact analysis （LTCA）, the actual meshing process of each gear pairs is simulated, and the time-varying mesh stiffness excitations are obtained, which can improve the numerical precision. Second- ly, by using the lumped mass method, the bending-torsional coupling three dimensional dynamic model of the dual power-split transmission is established, and the identical dimensionless equations are deduced by elimina- ting the effect of rigid displacement and the method of dimensional normalization. Finally, by the method of the fourth order Runge-Kutta algorithm with variable step lengths, the responses of this system in a frequency domain and time domain are obtained, and the dynamic load change characteristics of each gear pairs are analyzed. The results show that the establishment, solution and analysis of the system dynamics model could provide a basis for the dynamic design, and have an important significance for the dynamic efficiency analysis and dynamic perform- ance optimization design of the dual power-split transmission.

车辆道路行驶阻力国六测试方法分析比对

依据现行国家标准GB 18352.6—2016《轻型汽车污染物排放限值及测量方法(中国第六阶段)》的规定要求,通过三种方法(固定式风速仪滑行法、车载风速仪滑行法、基于车辆参数计算默认道路载荷法)获取测试样车的车辆道路行驶阻力,模拟出滑行阻力系数,用于后续对轻型混合动力电动汽车能量消耗量进行测试,进而分析优化汽车燃油消耗量和汽车续驶里程。测试结果表明,采用车载风速仪滑行法和固定式风速仪滑行法对样车进行摸底试验,获得的车辆道路行驶阻力能有效模拟出道路阻力系数,优化OVC-HEV测试数据。

两种方案设计下支架材料对无牙上颌种植固定修复影响的有限元分析

背景:在上颌无牙颌种植体支持式固定修复治疗中,上部支架结构材料的选择及不同远端种植体植入方式的设计密切影响着全口种植修复体的长期稳定性。目的:采用三维有限元方法,综合研究3种材料的上部支架及2种固定种植设计方案对上颌种植固定修复生物力学的影响。方法:根据1名健康成人正常颌的锥形束CT资料,采用Mimics软件分离上颌骨及上颌牙列三维实体模型,利用Geomagic Studio软件结合具体的模型参数构建无牙上颌全牙弓种植固定义齿的三维有限元模型。依据上颌后牙区远中种植体植入方式设计的不同,建立两种方案模型:方案1,按照临床常规应用的“All-on-4”设计,即2个种植体垂直植入上颌骨的双侧侧切牙区,另2个种植体则倾斜30°植入到双侧第二前磨牙区;方案2,即2个种植体垂直植入上颌骨的侧切牙区,后牙区采用2个短植体垂直植入双侧第二前磨牙区;在两种方案设计中使用3种材料(钛、氧化锆及聚醚醚酮)分别对上部支架结构进行赋值,得到6个模型,随后对比分析在斜向加载力方向下种植体、周围骨组织及上部支架结构的生物力学效果。结果与结论:①无论采用何种材料的上部支架,在两种无牙颌种植固定修复方案设计下,每个模型的最大应力峰值均分布于后侧种植体周围的颈部区域和皮质骨处;②与方案2中采用短种植体垂直植入的替代设计相比,方案1在上颌骨上显示出更为理想的应力分布;③由聚醚醚酮材料构建的支架模型,向上颌骨接近载荷区的种植体和周围骨组织传递了更高的应力,其次是钛、氧化锆;对于支架本身,聚醚醚酮上部支架内部应力峰值均明显小于氧化锆和钛支架;在3种上部支架材料中,选用氧化锆支架更有利于分散种植体及骨组织的应力分布;④结果提示,两种无牙颌种植固定修复设计方案都可以应用于临床实践,但从生物力学角度上考虑,方案1设计中的种植体、周围骨组织及上部支架的应力分散较为理性,更有利于无牙颌患者固定种植修复的远期预后;上部支架材料对种植体-骨界面的应力分布有着一定的影响。

风荷载下伸臂桁架-ATMD组合系统最优伸臂桁架位置研究

基于虚拟激励法和最优控制理论,提出伸臂桁架-主动调谐质量阻尼器(ATMD)组合系统的风振最优控制模型。首先推导伸臂桁架主体结构与ATMD耦合后的控制运动微分方程组并基于虚拟激励法求解该方程组,发展新的伸臂桁架-ATMD组合系统数值简化模型。基于新提出的组合系统数值简化模型,应用固定点理论求解ATMD最优控制力,获得伸臂桁架-ATMD组合系统的最优控制力模型。将新提出的伸臂桁架-ATMD组合系统数值简化模型和最优控制力模型进行有效数值组合,构建该组合系统的整体最优控制模型。将本文提出的基于固定点理论的最优控制模型与基于线性二次规划方法的最优控制模型、被动最优控制模型和无控制模型进行对比分析。最后应用基于固定点理论的最优控制模型对伸臂桁架-ATMD组合系统的最优伸臂桁架位置进行单参数敏感性分析,研究最优伸臂桁架位置对不同结构影响因素的敏感性以及ATMD对不同类型伸臂桁架系统的抗风控制效果。研究结果表明:主体结构伸臂桁架系统类型不同,不同控制方案的作用效果不同,且主动控制方案对加速度响应的控制效果优于对位移响应的控制效果;与纯伸臂桁架系统相比,风荷载作用下主动调谐质量阻尼器对组合系统的最优伸臂桁架位置影响不大,且最优位置对伸臂桁架刚度、核心筒刚度和外柱与核心筒间距离都有非常高的敏感性;风荷载作用下主体结构中的阻尼会限制ATMD对结构响应控制作用的发挥。

The Effect of Non-Contact Conditions in a Splinted Fixed Partial Denture on the Load Sharing Mechanism： A Finite Element Study

A computer-aided design model for a fixed partial denture was constructed and used in a finite element analysis to study the overall load sharing mechanism between the fixed partial denture and oral structures while the denture base rested on the al- veolar ridge. To investigate the consequences of non-contact conditions, three additional models were generated incorporating a uniform clearance of 0.125 mm, 0.25 mm, and 0.5 mm, respectively. A 100 N static load located at the free end of the prosthesis was applied while the distal portion of the jaw was set fixed. The results show that whilst releasing the ridge almost entirely, the presence of the clearance drastically increased the load on the splinting teeth. A pull-out force on the canine tooth of about 44 N was computed, accompanied by a mesio-distal moment of about 500 N.cm. The combination of which was similar to the tooth extraction maneuver performed by the dentist. In contrast, the second premolar was found to bear a push-in force of almost 115 N. The first molar, though barely solicited in the contact condition, became substantially loaded in non-contact conditions, which validates the choice of sacrificing three teeth to support the denture.

新型电力系统中异质调频机组分布式协同AGC方法研究

“双碳”目标的实施加速了新型电力系统发展。然而,新型电力系统的转动惯量和调节能力逐渐难以适应复杂多变的负荷变化。因此,开发更高效、更快速的调频资源参与自动发电控制(automatic generation control,AGC)已成为刻不容缓之事。但是,不同调频机组之间的异质性显著,包括机组模型、容量和响应速度的差异,这对AGC提出了挑战。为了提升异质调频资源参与AGC的性能,该文提出了一种分布式协同AGC方法。首先,基于分布式固定时间一致性理论提出了一种分布式固定时间区域控制偏差(area control error,ACE)发掘算法。随后,各AGC机组根据获取的ACE信息设计独立的PI控制器参与频率调节。在ACE调节的最后阶段,根据各机组出力的标幺值,设计了分布式固定时间功率均分控制器,控制低速AGC机组承担更多的功率调整量,从而释放高速AGC机组的容量并为下一轮AGC服务做好准备。通过对包含5种不同调频单元的两区域电力系统进行仿真研究,验证了所提分布式协同AGC方法的性能。结果表明,所提方法可以有效地提高系统的调频性能,且能够在设计的时间内实现期望的有功功率分配。