System verification is an ever-lasting system engineering challenge. The increasing complexity in system simulation requires some level of expertise in handling the idioms of logic and discrete mathematics to correctly drive a full verification process. It is recognized that visual modeling can help to fill the knowledge gap between system experts and analysis experts. However, such an approach has been used on the one hand to specify the behavior of complex systems, and on the other hand to specify complex requirement properties, but not simultaneously. This paper proposes a framework that is unique in supporting a full system verification process based on the graphical modeling of both the system of interest and the requirements to be checked. Patterns are defined to transform the resulting models to formal specifications that a model checker can manipulate. A real-time crossing system is used to illustrate the proposed framework.

Since high performance is essential to the functioning of emergency departments (EDs), they must constantly pursue sensible and empirically testable improvements. In light of recent advances in computer science, an increasing number of simulation-based approaches for studying and implementing ED performance optimizations have become available in the literature. This paper aims to offer a survey of these works, presenting progress made on the topic while indicating possible pitfalls and difficulties in EDs. With that in mind, this review considers research studies reporting simulation-based optimization experiments published between 2007 and 2019, covering 38 studies. This paper provides bibliographic background on issues covered, generates statistics on methods and tools applied, and indicates major trends in the field of simulation-based optimization. This review contributes to the state of the art on ED modeling by offering an updated picture of the present state of the field, as well as promising research gaps. In general, this review argues that future studies should focus on increasing the efficiency of multi-objective optimization problems by decreasing their cost in time and labor.

The anisotropy of single crystal copper and crystal orientation have a significant effect on the micro-milling process. At present, there is no systematic and perfect theory to explain the influence of single crystal orientation on the micro-milling process. Therefore, it is urgent to conduct an in-depth study on the micro-milling process of single crystal copper. In this paper, based on the theory of crystal plasticity, considering the anisotropy of single crystal copper, the VUMAT material subroutine of single crystal copper is programmed by the Fortran language, and the crystal plastic constitution is introduced into the finite element simulation. The model of the micro-milling tool and work-piece is established and meshed. Considering the friction among the tool and the work-piece, material removal, etc., the three-dimensional finite element simulation model of single crystal copper micro-milling process is achieved by ABAQUS software. The validity of the simulation model of the micro-milling process of single crystal copper considering the single crystal plastic constitution is verified by experimental micro-milling forces. The research has explored a feasible way to predict the micro-milling force of single crystal copper, and has provided a reference for revealing the micro-milling mechanism of single crystal materials.

The field of public health increasingly utilizes computational models. In this context, computer scientists are confronted with moral dilemmas like those around modeling the distribution of scarce resources. However, there is a lack of research on the ethical implications of computer modeling and simulation (M&S). In this paper I aim to show that taking a transdisciplinary ethical perspective is useful when analyzing these implications. The practice of modeling geospatial distribution of automated external defibrillators for sudden cardiac arrest treatment is used as a case study. It is shown that there exists no consensus on what theory of justice should underlie choices in computer M&S of public health resources, and that professionals struggle with building equity considerations into their models. The example highlights new ethical consequences arising at the nexus of public health and M&S. Computer models and simulations are not morally neutral, but have the effect of making those involved in their creation more responsible for making just choices. For some moral dilemmas, such as those related to distributive justice, there may be no correct solution that can be readily modeled. Promoting professional responsibility through a code of ethics will not help prescribe a right course of action in these situations. I suggest therefore that procedural justice and deliberation with a range of stakeholders is needed to take ethical considerations into account “by design” when developing computer models and simulations for public health policy. Future research should reflect on the content and practical procedures for these deliberations.

Inspired by the superior fixed and traction characteristics of ostrich foot toenails, we devised, optimized and manufactured the single structure and group arrangement of a new-style bionic spike for sprint shoes to improve athletic performance. The tractive performance of the bionic spike was tested by finite element analysis and experimental verification. The optimized single structure of the bionic spike had a top slope angle of 13° and the radius of the medial groove of 7.3 mm. Compared with the conventional conic spike, the maximal and stable extrusion resistances of the single bionic spike decreased by about 25% and 40% respectively, while the maximal and stable horizontal thrusts increased by about 16% and 10%, respectively. In addition, the arrangement of the bionic spikes was also optimized. Compared with the conventional spike group, the maximal and stable extrusion resistances of the bionic spike group decreased by 11.0% and 6.2%, respectively, while the maximal and stable horizontal thrusts increased by 20.0% and 16.0%, respectively. The current results may provide useful mechanical information that can help develop a better design of athletic shoes with the potential for advanced performance.

Automated parking systems play an important role in improving the utilization of parking facilities, particularly in busy public areas that receive many visitors, such as airports, government buildings, and shopping malls. The current parking facilities of airports in Saudi Arabia use barrier gates and ticket-issuing machines. Such parking facilities increase the waiting time at every circulation point, especially at the entry and exit terminals, and when a large number of vehicles are waiting in the queue. In this study, we address this problem by applying an automated technology at the entry/exit terminals of the current parking facilities. In particular, we introduce a parking system that uses radio-frequency identification (RFID) technology for the entry and exit terminals. The basic components of the current entry/exit system and the proposed one (i.e., using RFID technology) are described in detail. Subsequently, a simulation model for the entry/exit system using Arena 14.7 is developed to evaluate the current and proposed entry/exit systems. The evaluation is based on two performance metrics: average waiting time and average number of waiting vehicles. The developed simulation model is validated using actual data through a systematic procedure. The outcome of this study shows that the proposed RFID-based entry/exit system significantly outperforms the current system. Similarly, the validated results confirm the robustness of the simulation model. Thus, it can be concluded that an RFID-based parking system will provide an effective solution for parking facilities.

Passengers are more susceptible to experiencing motion sickness (MS) than drivers. The difference in the severity of MS is due to their different head movement behavior during curve driving. When negotiating a curve, the passengers tilt their heads towards the lateral acceleration direction while the drivers tilt their heads against it. Thus, to reduce the passengers’ level of MS, they need to reduce their head’s tilting angle towards the lateral acceleration direction. Designing MS minimization strategies is easier if the correlation between the head movement and lateral acceleration is known mathematically. Therefore, this paper proposes the utilization of a time delay neural network (TDNN) to model the correlation of the occupant’s head movement and lateral acceleration. An experiment was conducted to gather real-time data for the modeling process. The results show that TDNN manages to model the correlation by producing a similar output response to the actual response. Thus, it is expected that the correlation model could be used as an occupant’s head movement predictor tool in future studies of MS.

This paper presents the concept of a novel telemanipulator for minimally invasive surgery, along with numerical analysis to validate the main system performance. The proposed kinematic structure consists of a passive and an active module. The passive module is similar to the Selective Compliance Assembly Robot Arm - SCARA robot. The active module is based on a parallelogram mechanism. The results of the numerical study are discussed, focusing on the influence of geometry parameters of the kinematic chain on the displacement accuracy of the end-effector. In particular, the paper deals with the identification of the main factors that impact the position accuracy of the robot.

Subsea Mudlift Drilling is a newly developed technology that provides a good solution to the problem of narrow pressure window in deep-water areas. However, current researches on Subsea Mudlift Drilling seldom focus on hydrate formation in a wellbore. Considering the shortcomings of current researches, a heat transfer model is established in this paper considering the specific flow path during Subsea Mudlift Drilling. A numerical model for the pressure profile during Subsea Mudlift Drilling is also established considering the lift force by the subsea pump. On basis of these models, a prediction method for the hydrate formation region is proposed, combining the hydrate phase equilibrium equation. In addition, a series of numerical simulations are conducted, which indicate that hydrate is easier to form during Subsea Mudlift Drilling than during conventional drilling. In order to reduce the hydrate formation region, a smaller head for the subsea pump, smaller diameter of the return line, larger displacement of the drilling fluid, and higher concentrations of inhibitors are suggested during Subsea Mudlift Drilling. On the basis of the numerical simulation results, an optimization method of hydraulic parameters for Subsea Mudlift Drilling is proposed. Conclusions and suggestions in this paper can help engineers to reduce hydrate formation during subsea Mudlift Drilling.

This paper deals with the adaptation of energy-based realization-preserving model-reduction techniques for object-oriented models implemented in Modelica. An approach originally developed for bond graphs, where energy-related heuristics were used to identify the components contributing the most to the model’s salient dynamics, was extended to more heterogeneously formulated models in Modelica. A prototype toolbox was developed inside the modeling environment OpenModelica. Its applicability was demonstrated with two examples. Although the model-reduction tool cannot reduce the model completely automatically, it may still offer many useful insights and hints to the user.