Static Simulator Research Articles

High accurate three-dimensional neutron noise simulator based on GFEM with unstructured hexahedral elements

Abstract The purpose of the present study is to develop the 3D static and noise simulator based on Galerkin Finite Element Method (GFEM) using the unstructured hexahedral elements. The 3D, 2G neutron diffusion and noise equations are discretized using the unstructured hexahedral by considering the linear approximation of the shape function in each element. The validation of the static calculation is performed via comparison between calculated results and reported data for the VVER-1000 benchmark problem. A sensitivity analysis of the calculation to the element type (unstructured hexahedral or tetrahedron elements) is done. Finally, the neutron noise calculation is performed for the neutron noise source of type of variable strength using the Green function technique. It is shown that the error reduction in the static calculation is considerable when the unstructured tetrahedron elements are replaced with the hexahedral ones. Since the neutron flux distribution and neutron multiplication factor are appeared in the neutron noise equation, the more accurate calculation of these parameters leads to obtaining the neutron noise distribution with high accuracy. The investigation of the changes of the neutron noise distribution in axial direction of the reactor core shows that the 3D neutron noise analysis is required instead of 2D.

Design and analysis of a star simulator suitable for confined space

Star sensors on satellite require on-orbit thermal control via a radiator. Because of spatial interference between the star sensor radiator and the star simulator for the sensor, the radiator needs to be removed temporarily during the star simulator test. In order to solve the problem, a new structure for the star simulator which is suitable for confined space is designed. By analysing the operation process and the spatial feature of the star simulator test, a miniaturized star simulator structure is precisely sized by using the micro-deformation at working condition. Also, the tolerance of the optical axis angle and rotation angle is calculated. The on-board test verifies the feasibility that the new static star simulator is compatible with the shape of star sensor radiator and performs well at reducing operational risk. The application of the new star simulator enhances assembly efficiency benefited from the compact size.

Driver fatigue detection through multiple entropy fusion analysis in an EEG-based system.

Driver fatigue is an important contributor to road accidents, and fatigue detection has major implications for transportation safety. The aim of this research is to analyze the multiple entropy fusion method and evaluate several channel regions to effectively detect a driver's fatigue state based on electroencephalogram (EEG) records. First, we fused multiple entropies, i.e., spectral entropy, approximate entropy, sample entropy and fuzzy entropy, as features compared with autoregressive (AR) modeling by four classifiers. Second, we captured four significant channel regions according to weight-based electrodes via a simplified channel selection method. Finally, the evaluation model for detecting driver fatigue was established with four classifiers based on the EEG data from four channel regions. Twelve healthy subjects performed continuous simulated driving for 1–2 hours with EEG monitoring on a static simulator. The leave-one-out cross-validation approach obtained an accuracy of 98.3%, a sensitivity of 98.3% and a specificity of 98.2%. The experimental results verified the effectiveness of the proposed method, indicating that the multiple entropy fusion features are significant factors for inferring the fatigue state of a driver.

Virtual Reality Simulator Training for Shoulder Arthroscopy Procedures

Arthroscopic procedures, as compensatory tracking tasks requiring refined eye-hand coordination, are conducive to virtual reality (VR) simulation. This study tested the efficacy of a VR simulator vs a Sawbones static simulator in training orthopaedic residents to perform specific shoulder arthroscopic tasks. Thirty-eight residents were randomized into a training routine on either a VR or static simulator for learning an arthroscopic shoulder stabilization technique. Before and after 4 weeks of prescribed training on their respective simulators, each resident performed shoulder stabilization on cadavers, during which basic skills and ability to perform the specific procedures were graded by a staff surgeon. Regression modeling was used to assess “pre” and “post” training scores, and simulator preference was compared between simulator used for training and baseline resident experience. There was no difference in observed scores or change in scores between residents who trained on the VR vs static simulator (p = 0.3805); however, the whole group experienced an increase in score regardless of training simulator (20.8 ± 18 vs 24.3 ± 6.3 points, p = 0.0424). Majority (89%) of residents requested more simulator training during residency. Junior arthroscopists preferred the VR simulator, while senior arthroscopists preferred the static simulator (p = 0.043). All participants improved after 4 weeks of prescribed training regardless of simulator model. Senior residents preferred the static model, possibly due to the ability to do specific procedures with specific implants, while junior residents seemed to benefit most from basic skills exercises with the VR simulator. Further research to determine optimal training methods to facilitate efficient, learner-centered skill acquisition is necessary.

Analysis of the Influence of PCI Planning on the Physical Uplink Control Channel in LTE

In Long Term Evolution (LTE) systems, the physical cell identity (PCI) assigned to a cell during network planning determines the set of sequences used by subscribers as de-modulation reference signals (DM RS) in the uplink (UL). A proper assignment of PCIs must prevent neighbor cells from using the same DM RS to avoid interference problems, thus ensuring adequate performance both in control and user data channels in the uplink. In this paper, a comprehensive analysis is carried out to quantify the impact of PCI planning on the performance of physical uplink control channel (PUCCH) in LTE. First, a novel analytical model that reflects the influence of PCI planning on interference and outage probability due to DM RS collisions in PUCCH is presented. Based on this model, PUCCH performance with several classical PCI planning schemes is evaluated with a static system-level simulator implementing a real network scenario. Simulated cases cover different PUCCH frame formats, different UL power control (PC) schemes and both regular and irregular traffic scenarios. Results show that a PCI plan constructed solely based on avoiding PCI collision/confusion and reference signals collisions in the downlink achieves near-optimal performance in terms of DM RS collisions in PUCCH, but, however, in extreme cases, DM RS collisions caused by neighbor cells sharing the same sequence might degrade PUCCH performance significantly.

Bioaccessibility of selenium from cooked rice as determined in a simulator of the human intestinal tract (SHIME).

As an essential but also potentially toxic element, both overexposure and underexposure to selenium (Se) can significantly affect public health. Rice is a common source of Se, especially in Asia. Not all Se may be released from the rice and become available for absorption into the bloodstream upon digestion in the gastrointestinal tract. Therefore, the bioaccessibility of Se in cooked white (polished) rice was assessed in vitro using the static gastrointestinal simulator SHIME (Simulator of the Human Intestinal Microbial Ecosystem). The common cooking procedure in China prior to consumption [i.e. boiling at low rice:water ratios (1:3) until all of the water is absorbed into the rice] did not change total Se levels in the rice. Gastrointestinal digestion of the cooked rice matrix revealed a Se bioaccessibility of 67-76% of total Se. Subsequent microbial activity in the colon reduced the accessibility of Se in the cooked rice to 51-62%. Not all Se present in cooked white rice should be considered as being bioavailable in the small intestine. A minor part is transferred with the remaining food matrix to the colon, where it is available for the microbial metabolism. © 2017 Society of Chemical Industry.

Masticatory System Biomechanical Photoelastic Simulation fot the Comparision of the Conventional and Uni-Lock Systems in Mandibular Osteosynthesis

The biomechanical consequences of the interaction between titanium trauma plates and screws and the fractured mandible are still a matter of investigation. The mathematical and biomechanical models that have been developed show limitations and the experimental studies are not able to reproduce muscle forces and internal stress distributions in the bone-implant interface and mandibular structure. In the present article we show a static simulator of the masticatory system to demonstrate in epoxy resin mandibular models, by means of 3D (three-dimensional) photoelasticity, the stress distribution using different osteosynthesis methods in the mandibular angle fractures. The results showed that the simulator and 3D photoelasticity were a useful method to study interactions between bone and osteosynthesis materials. The “Lock” systems can be considered the most favourable method due to their stress distribution in the epoxy resin mandible. 3D photoelasticity in epoxy resin models is a useful method to evaluate stress distribution for biomechanical studies. Regarding to mandibular osteosynthesis, “lock” plates offer the most favourable stress distribution due to being less aggressive to the bone

Identification of flight state under different simulator modes using improved diffusion maps

To identify the difference between dynamic and static simulator modes, a novel data analyzing method was presented in this paper using flight data sampled from manual flight task. The proposed method combined diffusion maps and kernel fuzzy c-means algorithm (KFCM) to identify types of flight data. Hybrid bacterial foraging (BF) and particle swarm optimization (PSO) algorithm (BF-PSO) was also introduced to optimize unknown parameters of the KFCM. This algorithm increased the possibility to find the optimal values avoided being trapped in local minima. The clustering accuracy of the proposed method applied in flight dataset demonstrated this method had the ability to recognize the types of flight state. The results of the paper indicated that the pilots movement sensing influenced pilot performance under the manual departure task.

Signal Simulation on Static Test of Guidance Station of One Antiaircraft Missile

In order to improve trainees’ operational quality of static test of guidance station of one antiaircraft missile, a static testing simulator is necessary to gain the goal. It is obvious that the key problem of developing the simulator is how to generate the static testing signals of the simulator. Aiming to solve the problem, at first, the paper adopts a standard called signal testing definition(STD), which is applied to describe simulating signals used for static testing simulation of guidance station of one antiaircraft missile; then those simulating signals for the static testing simulation are implemented based on the platform Labwindows/CVI, and D/A converters are employed for generating physical static testing signals, which are outputted through operational panels or interfaces of the static testing simulator. So the mentioned process could be helpful to realize the static testing simulator of guidance station of one antiaircraft missile.

Self-tuning of remote electrical tilts based on call traces for coverage and capacity optimization in LTE

Adjusting antenna tilts is one of the most powerful techniques to solve coverage and capacity problems in cellular networks. In this paper, a novel self-tuning algorithm for adjusting antenna tilts in a Long-Term Evolution (LTE) system on a cell-by-cell basis is presented. The aim of the algorithm is to improve both network coverage and overall spectral efficiency, while eliminating cell overshooting problems. For this purpose, several new indicators are computed to detect insufficient cell coverage, cell overshooting, and abnormal cell overlapping from information available in connection traces. Algorithm assessment is carried out over a static system-level simulator implementing different real macrocellular scenarios. During the analysis, the proposed algorithm is compared with classical self-tuning algorithms that modify other base station parameters, such as transmission power or antenna tilt. Results show that the proposed algorithm can solve overshooting and overlapping problems more effectively than previous algorithms, regardless of the scenario.

具有均匀天空背景的高精度静态星模拟器设计

具有均匀天空背景的高精度静态星模拟器设计

Design of Light Source System and Optical System for a Static Star Simulator

This paper introduced a scheme of using cold cathode planar backlight, and presented the power supply circuit for light source. According to the analysis, parameters of static star simulator were determined, and then a large field, small distortion and small field curvature collimating objective lens was designed by using transmission optical system. The imaging analysis results show that the design can satisfy the request.

Effect of gastric and small intestinal digestion on lactic acid bacteria activity in a GIS1 simulator.

The selection of probiotic strains resistant to gastrointestinal transit is an important stage when developing supplements that contain viable biomass. A total of six strains belonging to different genotypes were tested and compared with both a positive and negative control (Lactobacillus plantarum 5s). Significant differences were found between strains as a result of gastrointestinal transit using the in vitro GIS1 static simulator. The Lactobacillus rhamnosus 428ST strain showed maximum viability as a result of in vitro transit, featuring a survival capacity value, Cs, of over 50 ± 0.01%. The remaining genotypes that were tested showed significant reductions in the enzymes and bile salts at the time of action. The value of the survivability capacity was directly correlated with the synthesis of exopolysaccharides and lactic acid. The test results of the GIS1 system have been compared with those of other studies on gastrointestinal transit resistance that used dynamic models.

Valid representation of a highly dynamic collision avoidance scenario in a driving simulator

In Germany the second-most frequent accidents in road traffic are rear-end collisions. For this reason rear-end collisions are quite important for accident research and the development of driving safety systems. To examine the functionality and to design the human–machine-interface of new driving safety systems, especially in the early development phase, subject tests are necessary. Because of the great hazard potential of such safety critical scenarios for the test persons, they are often conducted in a driving simulator (DS). Accordingly, validity is an important qualification to ensure that the findings collected in a simulated test environment can be directly transferred to the real world.This paper regards the question of driving behavior validity of DS in critical situations. There are hardly any validation studies which analyze the driving behavior in a specific collision avoidance situation.The validation study described in this paper aims to evaluate the behavioral validity of a fixed-base simulator in a collision avoidance situation. For this reason a field study from 2007 was replicated in a fixed-base simulator environment.The main questions of this validation study were if the driver can notice an active hazard braking system and if the driving behavior in a static simulator can be valid in such a critical situation.The key finding of the study states that there is no driving behavior validity in a static driving simulator for the tested dynamic scenario. The missing vestibular feedback causes a different behavior of the participants in field and simulator. The resulting absence of comparability leads to non-valid performance indicators. But these indicators are key parameters for analyzing the function and acceptance of active braking systems. So the question arises, which motion performance does a motion base have to provide in order to achieve valid acceleration simulation of such a highly dynamic collision avoidance scenario. The DS’s performance is measured in workspace, velocity and acceleration.

A computationally efficient method for self-planning uplink power control parameters in LTE

Uplink power control has a strong impact on the performance of mobile communication networks. In this work, an automatic parameter planning algorithm for the standardized power control scheme in the physical uplink shared channel (PUSCH) of long term evolution LTE is proposed. The method is conceived for the network design stage, when network measurements are still not available. The proposed heuristic algorithm can handle irregular scenarios at a low computational complexity. For this purpose, the parameter planning problem in a cell is formulated analytically through the combination of multiple regular scenarios built on a per-adjacency basis. Method assessment is carried out over a static system-level simulator implementing a real scenario. Results show that the proposed method can improve average user throughput and cell-edge user throughput when compared to current vendor approaches, which provide network-wide uniform parameter settings.

Development of three-dimensional capabilities for modelling stationary fluctuations in nuclear reactor cores

This paper presents the development of a numerical tool meant at modelling the effect of stationary fluctuations in nuclear cores for systems cooled with either liquid water or boiling water. The originating fluctuations are defined for the variables describing the boundary conditions of the system, i.e. inlet velocity, inlet enthalpy, and outlet pressure. The tool then determines in the frequency domain the three-dimensional distributions within the core of the corresponding fluctuations in neutron flux, coolant density, coolant velocity, coolant enthalpy, and fuel temperature. The tool is thus based on the simultaneous modelling of neutron transport, fluid dynamics, and heat transfer in a truly integrated and fully coupled manner. The modelling of neutron transport relies on the two-group diffusion approximation and a spatial discretization based on finite differences. The modelling of fluid dynamics is performed using the Homogeneous Equilibrium Model, with a void fraction correction based on a pre-computed distribution of the static slip ratio (when two-phase flow conditions are encountered). Heat conduction in the fuel pins is also accounted for, and the heat transfer between the fuel pins and the coolant is modelled also using a pre-computed distribution of the heat transfer coefficient. The spatial discretization of the fluid dynamic and heat transfer problems is carried out using finite volumes. The tool, currently entirely Matlab based, requires minimal input data, mostly in form of the three-dimensional distributions of the macroscopic cross-sections and their relative dependence on coolant density and fuel temperature, the point-kinetic parameters of the core, as well as the three-dimensional distribution of the slip ratio (in case of two-phase flow conditions) and of the heat transfer coefficient. Such data can be provided by any static core simulator that thus needs to be run prior to using the present tool. In addition to briefly summarizing the different test cases used to verify the code, the paper also presents the results of simulations performed for a typical Pressurized Water Reactor and for a typical Boiling Water Reactor, as illustrations of the capabilities of the tool.

Assessment of early onset of driver fatigue using multimodal fatigue measures in a static simulator

Driver fatigue is an important contributor to road accidents. This paper reports a study that evaluated driver fatigue using multimodal fatigue measures, i.e., surface electromyography (sEMG), electroencephalography (EEG), seat interface pressure, blood pressure, heart rate and oxygen saturation level. Twenty male participants volunteered in this study by performing 60 min of driving on a static simulator. Results from sEMG showed significant physical fatigue (ρ < 0.05) in back and shoulder muscle groups. EEG showed significant (ρ < 0.05) increase of alpha and theta activities and a significant decrease of beta activity during monotonous driving. Results also showed significant change in bilateral pressure distribution on thigh and buttocks region during the study. These findings demonstrate the use of multimodal measures to assess early onset of fatigue. This will help us understand the influence of physical and mental fatigue on driver during monotonous driving.

Motion sickness evaluation and comparison for a static driving simulator and a dynamic driving simulator

This paper deals with driving simulation and in particular with the important issue of motion sickness. The paper proposes a methodology to evaluate the objective illness rating metrics deduced from the motion sickness dose value and questionnaires for both a static simulator and a dynamic simulator. Accelerations of the vestibular cues (head movements) of the subjects were recorded with and without motion platform activation. In order to compare user experiences in both cases, the head-dynamics-related illness ratings were computed from the obtained accelerations and the motion sickness dose values. For the subjective analysis, the principal component analysis method was used to determine the conflict between the subjective assessment in the static condition and that in the dynamic condition. The principal component analysis method used for the subjective evaluation showed a consistent difference between the answers given in the sickness questionnaire for the static platform case from those for the dynamic platform case. The two-tailed Mann–Whitney U test shows the significance in the differences between the self-reports to the individual questions. According to the two-tailed Mann–Whitney U test, experiencing nausea ( p = 0.019&lt;0.05) and dizziness ( p = 0.018&lt;0.05) decreased significantly from the static case to the dynamic case. Also, eye strain ( p = 0.047&lt;0.05) and tiredness ( p = 0.047&lt;0.05) were reduced significantly from the static case to the dynamic case. For the perception fidelity analysis, the Pearson correlation with a confidence interval of 95% was used to study the correlations of each question with the x illness rating component IR x, the y illness rating component IR y, the z illness rating component IR z and the compound illness rating IR tot. The results showed that the longitudinal head dynamics were the main element that induced discomfort for the static platform, whereas vertical head movements were the main factor to provoke discomfort for the dynamic platform case. Also, for the dynamic platform, lateral vestibular-level dynamics were the major element which caused a feeling of fear.

大视场高精度静态星模拟器的光学系统设计

大视场高精度静态星模拟器的光学系统设计

Development of excel based static simulator for various test phases of iter prototype cryoline

The prototype of multi process pipe ITER cryoline will be tested at ITER-India laboratory to measure heat load at 5 K and 80 K level, thermal shield temperature profile, stresses at critical locations and temperature of outer vacuum jacket during Loss of Insulation Vacuum scenario.