The Age Distribution Model and the Parity Progressive Model of Population and Their Equivalence

This paper proved that the integral form and the integro-differential form of the age-structured population equation (Lotka model) are equivalent, the integral form and the integro-differential form of the parity progressive population equation (Henry model) are equivalent. By the age parity progressive model, the equivalence between Lotka model and Henry Model is also proved. Moreover, the relation between the parity progression ratio and the total fertility rate is given.

PROGRESSIVE FRAGMENT MODELING OF FAILURE WAVE IN CERAMICS UNDER PLANAR IMPACT LOADING

Polycrystalline ceramics have heterogeneous meso-structures which result in high singularity in stress distribution. Based on this, a progressive fragment model was proposed which describes the failure wave formation and propagation in shocked ceramics. The governing equation of the failure wave was characterized by inelastic bulk strain with material damage and fracture. And the inelastic bulk strain consists of dilatant strain from nucleation and expansion of microcracks and condensed strain from collapse of original pores. Numerical simulation of the free surface velocity was performed in good agreement with planar impact experiments on 92.93% aluminas at China Academy of Engineering Physics. And the longitudinal, lateral and shear stress histories upon the arrival of the failure wave were predicted, which present the diminished shear strength and lost spall strength in the failed layer.

PROGRESSIVE FRACTURE MODELING OF THE FAILURE WAVE IN IMPACTED GLASS

The failure wave has been observed propagating in glass under impact loading since 1991. It is a continuous fracture zone which may be associated with the damage accumulation process during the propagation of shock waves. A progressive fracture model was proposed to describe the failure wave formation and propagation in shocked glass considering its heterogeneous meso-structures. The original and. nucleated microcracks will expand along the pores and other defects with concomitant dilation when shock loading is below the Hugoniot Elastic Limit. The governing equation of the failure wave is characterized by inelastic bulk strain with material damage and fracture. And the inelastic bulk strain consists of dilatant strain from nucleation and expansion of microcracks and condensed strain from the collapse of the original pores. Numerical simulation of the free surface velocity was performed and found in good agreement with planar impact experiments on K9 glass at China Academy of Engineering Physics. And the longitudinal, lateral and shear stress histories upon the arrival of the failure wave were predicted, which present the diminished shear strength and lost spall strength in the failed layer.

A general framework for progressive point-sampled geometry

Recently unstructured dense point sets have become a new representation of geometric shapes. In this paper we introduce a novel framework within which several usable error metrics are analyzed and the most basic properties of the pro- gressive point-sampled geometry are characterized. Another distinct feature of the proposed framework is its compatibility with most previously proposed surface inference engines. Given the proposed framework, the performances of four representative well-reputed engines are studied and compared.

Multiple sclerosis：integration of modeling with biology,clinical and imaging measures to provide better monitoring of disease progression and prediction of outcome

Multiple Sclerosis（MS） is a major cause of neurological disability in adults and has an annual cost of approximately $28 billion in the United States. MS is a very complex disorder as demyelination can happen in a variety of locations throughout the brain; therefore, this disease is never the same in two patients making it very hard to predict disease progression. A modeling approach which combines clinical, biological and imaging measures to help treat and fight this disorder is needed. In this paper, I will outline MS as a very heterogeneous disorder, review some potential solutions from the literature, demonstrate the need for a biomarker and will discuss how computational modeling combined with biological, clinical and imaging data can help link disparate observations and decipher complex mechanisms whose solutions are not amenable to simple reductionism.

Progressive Failure Analysis of Composite/Aluminum Riveted Joints Subjected to Pull-Through Loading

Out-of-plane mechanical properties of the riveted joints restrict the performance of the wing box assembly of airplane.It is necessary to investigate the pull-through performance of the composite/metal riveted joints in order to guide the riveting design and ensure the safety of the wing box assembly.The progressive failure mechanism of composite/aluminum riveted joint subjected to pull-through loading was investigated by experiments and finite element method.A progressive damage model based on the Hashin-type criteria and zero-thickness cohesive zone method was developed by VUMAT subroutine,which was validated by both open-hole tensile test and three-point bending test.Predicted load-displacement response,failure modes and damage propagation were analysed and compared with the results of the pull-through tests.There are 4 obvious characteristic stages on the load-displacement curve of the pull-through test and that of the finite element model:first load take-up stage,damage stage,second load take-up stage and failure stage.Relative error of stiffness,first load peak and second load peak between finite element method and experiments were 8.1%,-3.3%and 10.6%,respectively.It was found that the specimen was mainly broken by rivet-penetration fracture and delamination of plies of the composite laminate.And the material within the scope of the rivet head is more dangerous with more serious tensile damages than other regions,especially for 90°plies.This study proposes a numerical method for damage prediction and reveals the progressive failure mechanism of the hybrid material riveted joints subjected to the pull-through loading.

Numerical Application of the Flamelet Model to Supersonic Turbulent Combustion

In this study,the flow field structure inside a scramjet combustor is numerically simulated using the flamelet/progress variable model.Slope injection is considered,with fuel mixing enhanced by means of a streamwise vortex.The flow field structure and combustion characteristics are analyzed under different conditions.Attention is also paid to the identification of the mechanisms that keep combustion stable and support enhanced mixing.The overall performances of the combustion chamber are discussed.

Study on Project Progress Curve Model

Because of the discrepancy of project types,the project progress curves present different characteristics.Studying project progress curves can reduce management risk of project and overall grasp the enforcement condition of the project.Combining project characteristic,this paper reaches 4 kinds of project progress curve patterns.If the front of the progress curve is concave,and its rear is protruding in the break point,it is named as S model.If its front is protruding and its rear is concave in the break point,it is named as the reverse side of S model.If the front and rear are concave in the break point,it is named as J model,and two half sections are both upward protruding,it is named as the reverse side of J model.Through a case study,it shows that application project progress curve model can better raise project management.

A FGR Software Model for Measuring the Effect of Technological Progress

The work of quantitative studying the effect of technological progress on economic growth, being of great complexity and far-reaching significance, has become a quite popular research topic in the world. In recent years there are a large number of scientists who are engaged in this research both at home and abroad.

Information Models for Forecasting Nonlinear Economic Dynamics in the Digital Era

The aim of this study was to develop an adequate mathematical model for long-term forecasting of technological progress and economic growth in the digital age (2020-2050). In addition, the task was to develop a model for forecast calculations of labor productivity in the symbiosis of “man + intelligent machine”, where an intelligent machine (IM) is understood as a computer or robot equipped with elements of artificial intelligence (AI), as well as in the digital economy as a whole. In the course of the study, it was shown that in order to implement its goals the Schumpeter-Kondratiev innovation and cycle theory on forming long waves (LW) of economic development influenced by a powerful cluster of economic technologies engendered by industrial revolutions is most appropriate for a long-term forecasting of technological progress and economic growth. The Solow neoclassical model of economic growth, synchronized with LW, gives the opportunity to forecast economic dynamics of technologically advanced countries with a greater precision up to 30 years, the time which correlates with the continuation of LW. In the information and digital age, the key role among the main factors of growth (capital, labour and technological progress) is played by the latter. The authors have developed an information model which allows for forecasting technological progress basing on growth rates of endogenous technological information in economics. The main regimes of producing technological information, corresponding to the eras of information and digital economies, are given in the article, as well as the Lagrangians that engender them. The model is verified on the example of the 5th information LW for the US economy (1982-2018) and it has had highly accurate approximation for both technological progress and economic growth. A number of new results were obtained using the developed information models for forecasting technological progress. The forecasting trajectory of economic growth of developed countries (on the example of the USA) on the upward stage of the 6th LW (2018-2042), engendered by the digital technologies of the 4th Industrial Revolution is given. It is also demonstrated that the symbiosis of human and intelligent machine (IM) is the driving force in the digital economy, where man plays the leading role organizing effective and efficient mutual work. Authors suggest a mathematical model for calculating labour productivity in the digital economy, where the symbiosis of “human + IM” is widely used. The calculations carried out with the help of the model show: 1) the symbiosis of “human + IM” from the very beginning lets to realize the possibilities of increasing work performance in the economy with the help of digital technologies;2) the largest labour productivity is achieved in the symbiosis of “human + IM”, where man labour prevails, and the lowest labour productivity is seen where the largest part of the work is performed by IM;3) developed countries may achieve labour productivity of 3% per year by the mid-2020s, which has all the chances to stay up to the 2040s.

Tectonic Evolution of the Himalayan Collision Belt

This paper discusses the tectonic divisions of the Himalayan collision belt anddeals with the tectonic evolution of the collision belt in the context of crustal accretion in thefront of the collision belt, deep diapirism and thermal-uplift extension and deep material flow-ing of the lithosphere-backflowing. Finally it proposes a model of the tectonic evolution-progressive intracontinental deformation model-of the Himalayan belt.

STAGED PROGRESSION MODEL FOR EPIDEMIC SPREAD ON HOMOGENEOUS AND HETEROGENEOUS NETWORKS

In this paper, epidemic spread with the staged progression model on homogeneous and heterogeneous networks is studied. First, the epidemic threshold of the simple staged progression model is given. Then the staged progression model with birth and death is also considered. The case where infectivity is a nonlinear function of the nodes＇ degree is discussed, too. Finally, the analytical results are verified by numerical simulations.

Large Eddy Simulation of NO Formation in Non-Premixed Turbulent Jet Flames with Flamelet/Progress Variable Approach

To improve the NO modelling in turbulent flames,the flamelet/progress variable(FPV)model is extended by introducing NO mass fraction into the progress variable and incorporating an additional NO transport equation.Two sets of flamelet databases are tabulated with progress variables based on major species and NO mass fraction,respectively.The former is used for the acquisition of the main thermochemical variables,while the latter is employed for NO modelling.Moreover,an additional transport equation is solved to obtain the NO mass fraction,with the source term corrected using the scale similarity method.Model assessments are first conducted on laminar counterflow diffusion flames to identify lookup-related errors and assess the suitability of progress variable definitions.The results show that the progress variables based on major species and NO could correctly describe the main thermochemical quantities and NO-related variables,respectively.Subsequently,the model is applied to the large eddy simulation(LES)of Sandia flames.The results indicate that the extended FPV model improves the NO prediction,with a mean error for NO prediction at 55%,significantly lower than those of existing FPV models(130%and 385%).The LES with the extended FPV model quantitatively captures NO suppression in the mid-range of Reynolds numbers from 22400(Flame D)to 33600(Flame E),but underestimates the NO suppression at higher Reynolds numbers from 33600 to 44800(Flame F).This underprediction is primarily attributed to the underestimation of local extinction levels in flames with high Reynolds numbers.

Uncertainty evaluation for bearing fatigue property of CFRP double-lap,single-bolt joints

The considerable uncertainty in mechanical properties of composite bolted joints not only prevents advanced composite materials from efficient applications,but also threatens the safety and reliability of the aircraft structures.In this paper,the uncertainty in bearing fatigue properties of a CFRP double-lap,single-bolt joint was evaluated by combing a Progressive Fatigue Damage Model(PFDM)with the interval analysis method.In the PFDM,a residualstrain-based gradual material degradation model and a strain-based fatigue failure criterion were combined with a micromechanics-based sudden material degradation model to predict fatigue properties of the joint.Based on the interval analysis,the key uncertain parameters,which were firstly picked out from eighteen structural parameters of the joint,were described by estimated intervals,and the envelope cases were determined to estimate the lower and upper bounds of fatigue properties of the joint.The predicted results have the same tendency with the experimental results in literatures,which indicates that the PFDM combined with the interval analysis shows potential in efficiently evaluating the fatigue reliability of the complex bolted joints with an adequate accuracy.

Thermo-mechanical properties of RTM-made carbon fibre/polyimide composite attaching collar under transient heating

This study focuses on the thermo-mechanical properties of Carbon Fibre/Polyimide Composite(CFPC)attaching collars under transient heating.The CFPC attaching collars were fabricated by a high-temperature resin transfer moulding process,and their thermo-mechanical properties under the conditions of simultaneous transient heating and bending load were investigated.The results show that the attaching collar tends to fail at 118% of the limit load.The failure mode includes the fracture of the connecting screws,local extrusion damage of the hole edges,and slight ablation damage at the outer plies.And there is no observable residual deformation in the composite attaching collar.Furthermore,considering that the material properties vary with temperature,a progressive damage model based on the sequential thermo-mechanical coupling method was established to study the failure mechanism of the attaching collar.Finally,the damage factor of the CFPC was calculated to assess the safety status of the attaching collar.The results show that the primary damage modes of the composite attaching collar are intralaminar failure,which mainly occurs at the heat insulation layer and the hole edges,and these slightly affect the structural bearing capacity.A good correlation between the experiment and FEA is obtained.The test methods and analysis models proposed contribute to the safety assessment of composite structures under transient heating.

Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internal pressure

A theoretical solution is aimed to be developed in this research for predicting the failure in internally pressurized composite pressure vessels exposed to low-velocity impact.Both in-plane and out-of-plane failure modes are taken into account simultaneously and thus all components of the stress and strain fields are derived.For this purpose,layer-wise theory is employed in a composite cylinder under internal pressure and low-velocity impact.Obtained stress/strain components are fed into appropriate failure criteria for investigating the occurrence of failure.In case of experiencing any in-plane failure mode,the evolution of damage is modeled using progressive damage modeling in the context of continuum damage mechanics.Namely,mechanical properties of failed ply are degraded and stress analysis is performed on the updated status of the model.In the event of delamination occurrence,the solution is terminated.The obtained results are validated with available experimental observations in open literature.It is observed that the sequence of in-plane failure and delamination varies by increasing the impact energy.