Replicated point processes with application to population dynamics models

In this paper we study spatially clustered distribution of individuals using point process theory. In particular we discuss the spatially explicit model of population dynamics of Shimatani (2010) which extend previous works on Malécot theory of isolation by distance. We reformulate Shimatani model of replicated Neyman-Scott process to allow for a general dispersal kernel function and we show that the random immigration hypothesis can be substituted by the long dispersal distance property of the kernel. Moreover, the extended framework presented here is fit to handle spatially explicit statistical estimators of genetic variability like Moran autocorrelation index, Sørensen similarity index, average kinship coefficient. We discuss the pivotal role of the choice of dispersal kernel for the above estimators in a toy model of dynamic population genetics theory.

Parametric Structural Shape and Topology Optimization With a Variational Distance-Regularized Level Set Method

In conventional level set methods, the slope of the level set function needs to be well controlled to maintain the numerical stability during the topology optimization process. One common solution is to regularize the level set function to be a signed distance function, which is usually achieved by periodically implementing the so called re-initialization scheme to force the level set function to gain the desired signed distance property. However, the re-initialization scheme will bring some unwanted drawbacks to the optimization process, such as zero level set drifting, time consuming etc. In addition, re-initialization is usually implemented outside the optimization loop, which will cause convergence issues. In this paper, a distance regularization functional is introduced to the structural topology optimization objective functional to ensure the signed distance property of the level set function near the structure boundaries. This functional can also keep the level set function to be constant-value at positions far away from the structural boundaries. The radial basis function (RBF) based parameterization technique together with the mathematical programming are utilized to improve the potential capability of handling multiple constraints for the topology optimization. The combination of these two techniques makes the level set based topology optimization be capable of handling complicated multi-constrained problems with higher numerical efficiency, leaving no compromise to multiple drawbacks. To demonstrate the validity of the proposed scheme, benchmark examples on minimum compliance structural optimization are employed. This type of problem is computed by the conventional level set method with the introduced distance regularization functional, the RBF based parametric level set and at last, the distance regularized RBF based parametric level set separately to demonstrate their differences.

The relation between the codification and actual usage of the preposition VIRŠ

The analysis of Lithuanian syntax phenomena shows that there are many inconsistencies in the actual usage of some cases and prepositions and the codified rules of grammar that apply to them. This article concentrates on the actual usage of the Lithuanian preposition virš (‘above’) over the last decade. Thus the aim of the article is to discuss the relation between the codified rules of grammar and the current use of the preposition virš and to provide some guidelines in relation to the specification of its codified rules. The analysis of the usage of virš reveals that this preposition is used to refer to some excess in quantity, weight, time, distance, property or characteristic as well as to some overbalance, especially in periodical press. Such usage of the preposition virš is quite frequent both in spoken and written language. Currently, such usage of virš is considered by language standardisers as avoidable or even unacceptable in standard language. Such attitudes of linguists are based on the fact that the usage of virš in the sense of excess is a result of the influence of Slavic languages and dialects. The data of the analysis suggest that the usage of the preposition virš is becoming more common not only due to the above-mentioned reason but also because of the similarity or even overlap between the meanings of constructions used to refer to excess that are standardised and those that are considered to be avoidable. Systemic characteristics of the usage of the preposition virš show that its usage in the sense of excess is not necessarily in conflict with the standard language system. As a result, the pervasive use of the preposition virš in the sense of excess suggests that with regard to language users’ habits but not conflicting with language systematicity, linguists should consider the possibility of standardising the usage of virš in the sense of ‘excess’. Certainly, before anything can be put forward, more research on the usage of the preposition virš has to be carried out.

Simulative Research on the Influence of Vehicle Brake Deceleration on the Throw Distance Property of Human-Vehicle Accidents

Braking deceleration of passenger-car has great influence on the pedestrian motion process after collision of human-vehicle accident, but it is considered not enough in current accident reconstruction and vehicle-speed analysis. In order to improve the accuracy of accident reconstruction, a computer simulation model of pedestrian-vehicle accidents based on finite element (FE) method and human parameters of Chinese adult human body is established. In this article, based on the FE model, human-vehicle crash is simulated through involving the influence of braking deceleration of passenger-car. For the application of the vehicle-speed analysis, the motion performance of pedestrian after collision were studied and the correlation between the pedestrian throw distance and vehicle impact speed are investigated. The influence of braking deceleration in same impact speed is analyzed. Research results show that the vehicle brake deceleration has a certain influence on the throw distance of pedestrian and it should be taken into account on the accident reconstruction. We can conclude that pedestrian throw distance can be used to estimate the vehicle collision speed accurately when drivers take full braking measure during the crash.