The habituation of human postural responses to platform perturbations

The purpose of this study was to examine habituation and task on adaptation of postural responses to simulated wave-induced ship motions. Twenty-four participants (12 male and 12 female) performed four different tasks while being exposed to five platform motion profiles during two testing periods. The four tasks performed were: standing feet parallel stance, standing with feet in an in-step stance, holding of a 10 kg load, sagittal lifting/lowering of a 10 kg load. Motion induced correction (MIC) occurrence, corresponding platform motion parameters, and total time spent performing MICs were compared between trials and tasks. It was found that the number of MIC events and total time spent performing MICs differed significantly between trials, with the first trial for participants having more MIC events and more time spent performing postural corrections. The number of MIC events was reduced and total postural correction times were significantly quicker on the second day of testing. Results revealed significant differences in pitch and roll velocities between in-step and parallel standing and significant differences in pitch and roll accelerations between both standing tasks and MMH tasks (p < 0.05). These results suggest that MIC initiation is significantly affected by previous exposure, habituation to comparable platform motions, and task. Differences between tasks suggest that perturbation characteristics of MIC occurrence are potentially affected by shape of the base of support and additional load. These results could help explain difficulties in previous attempts to predict MIC occurrences purely upon platform motion characteristics.Relevance to industryThe results of this research suggest that when working in moving environments adaptation to motions may occur much faster than expected. Further adaptation may also occur after leaving the moving environment. These factors must be considered when evaluating offshore occupations.     

Mitigation of ground vibrations induced by high speed railways using double geofoam barriers: Centrifuge modeling

This paper presents a study of the propagation and mitigation of ground vibrations induced by high speed railways using 8 centrifuge tests. In the reported tests here, geofoam is used as a barrier in various locations and arrangements (single and double) to mitigate ground vibrations. The results show that the surface waves guide the propagation pattern of ground vibrations induced by high speed railways and also reveal that geofoam is a proper material for the mitigation of such ground vibrations. While the use of single geofoam barriers can reduce ground vibrations by up to 54.5%, their performance at low input frequencies are undesirable. Double geofoam barriers are used and tested in various locations to eliminate such inconvenient effects and improve the mitigation of ground vibrations. The results show that double geofoam barriers can mitigate the vibrations by about 14%–35% more than a single geofoam barrier and undesirable performances for the mentioned low input frequencies are also eliminated.     

Methylmercury in fish species used in preparing sashimi: A case study in Brazil

The objective of this work was to determine the organic and total mercury contents in twelve fish species used in preparing sashimi in Japanese restaurants and estimate the exposure to organic mercury due to the consumption of this food. The mercury species were quantified by atomic absorption with thermal decomposition and amalgamation. Total mercury was analyzed directly, whereas organic mercury was quantified after extraction with toluene in an acid medium using a microwave assisted system. Needlefish and tuna showed the highest levels of mercury species and salmon and mullet the lowest levels. The mean ratios between MeHg⁺/total Hg were 93% and 87% for sandperch and octopus, respectively, indicating that the most toxic form (organic Hg) predominates in these species. Exposure to methylmercury was estimated based on the PTWI and the results showed that the ingestion of 2 portions of needlefish and tuna exceeded the values established by 100%.     

动态目标移动数据管理技术研究

日益发展的预警监控技术的应用，在信息系统中积累了海量的动态目标运动信息，而这些数据并没有得到很好的管理和利用。本文提出采用移动对象数据库技术对动态目标移动数据进行有效的管理。     

Effects of Grinding with Microcrystalline Cellulose and Cyclodextrins on the Ketoprofen Physicochemical Properties

Ground mixtures of ketoprofen (KETO) with native crystalline β-cyclodextrin, amorphous statistically substituted methyl-β-cyclodextrin, and microcrystalline cellulose were investigated for both solid phase characterization (differential scanning calorimetry (DSC) powder X-ray diffractometry, and infrared (IR) spectrometry) and dissolution properties (dispersed amount and rotating disk methods) to evaluate the role of the carrier on the performance of the final product. The effects of different grinding conditions, partial sample dehydration, and 1 year storage at room temperature were also investigated. The results pointed out the importance of the carrier nature on the efficiency of the cogrinding process. Both cyclodextrins were much more effective than was microcrystalline cellulose, even though no true inclusion complex formation occurred by mechanochemical activation. The best results were obtained from ground mixtures with methyl-β-cyclodextrin, which showed the best amorphizing and solubilizing power toward the drug and permitted an increase of approximately 100 times its intrinsic dissolution rate constant, in comparison with the approximate 10 times increase obtained from ground mixtures with β-cyclodextrin.     

Prediction of ground motion parameters using randomized ANFIS (RANFIS)

In this paper, a novel neuro-fuzzy learning machine called randomized adaptive neuro-fuzzy inference system (RANFIS) is proposed for predicting the parameters of ground motion associated with seismic signals. This advanced learning machine integrates the explicit knowledge of the fuzzy systems with the learning capabilities of neural networks, as in the case of conventional adaptive neuro-fuzzy inference system (ANFIS). In RANFIS, to accelerate the learning speed without compromising the generalization capability, the fuzzy layer parameters are not tuned. The three time domain ground motion parameters which are predicted by the model are peak ground acceleration (PGA), peak ground velocity (PGV) and peak ground displacement (PGD). The model is developed using the database released by PEER (Pacific Earthquake Engineering Research Center). Each ground motion parameter is related to mainly to four seismic parameters, namely earthquake magnitude, faulting mechanism, source to site distance and average soil shear wave velocity. The experimental results validate the improved performance of the machine, with lesser computation time compared to prior studies.     

The influence of vehicle front-end design on pedestrian ground impact

Accident data have shown that in pedestrian accidents with high-fronted vehicles (SUVs and vans) the risk of pedestrian head injuries from the contact with the ground is higher than with low-fronted vehicles (passenger cars). However, the reasons for this remain poorly understood. This paper addresses this question using multibody modelling to investigate the influence of vehicle front height and shape in pedestrian accidents on the mechanism of impact with the ground and on head ground impact speed. To this end, a set of 648 pedestrian/vehicle crash simulations was carried out using the MADYMO multibody simulation software. Impacts were simulated with six vehicle types at three impact speeds (20, 30, 40 km/h) and three pedestrian types (50th % male, 5th % female, and 6-year-old child) at six different initial stance configurations, stationary and walking at 1.4 m/s.     

Vibrational Analysis for an Axially Moving Microbeam with Two Temperatures

In this article, the effect of two temperatures on an axially moving microbeam subjected to ramp-type heating is studied. The generalized thermoelasticity theory with one relaxation time model is used. The governing equations are expressed in Laplace transform domain. Based on Fourier series expansion technique, the inversion of Laplace transform is done numerically. Some comparisons have been shown in figures to present the effect of the temperature discrepancy and the transport speed on all the studied field quantities. Additional results across the thickness of the microbeam are presented graphically.     

Distributed moving horizon state estimation: Simultaneously handling communication delays and data losses

In this work, we consider distributed moving horizon state estimation of nonlinear systems subject to communication delays and data losses. In the proposed design, a local estimator is designed for each subsystem and the distributed estimators communicate to collaborate. To handle the delays and data losses simultaneously, a predictor is designed for each subsystem estimator. A two-step prediction-update strategy is used in the predictor design in order to get a reliable prediction of the system state. In the design of each subsystem estimator, an auxiliary nonlinear observer is also taken advantage of to calculate a reference subsystem state estimate. In the local estimator, the reference state estimate is used to generate a confidence region within which the local estimator optimizes its subsystem state estimate. Sufficient conditions under which the proposed design gives decreasing and ultimately bounded estimation error are provided. The effectiveness of the proposed approach is illustrated via the application to a chemical process example.     

Spatiotemporal variability of ground thermal properties in glacial sediments and implications for horizontal ground heat exchanger design

Thorough characterization of the spatiotemporal variability in soil thermal properties can facilitate better designs for horizontal geothermal heat pump (HGHP) systems by reducing ground heat exchanger (GHEX) costs. Results are presented from a new monitoring network installed across a range of glaciated terrains in Indiana (USA), including the first known observations of the dynamic range of thermal conductivity that occurs at the depth of horizontal GHEX installations. In situ thermal conductivity data can vary significantly on a seasonal basis in coarse-grained outwash sediments (0.8–1.4 W m⁻¹ K⁻¹), whereas clay- and silt-dominated moraine sediments have a dampened seasonal range within 10% of the annual mean. Thermal conductivity across the network ranges from 0.8 to 2.0 W m⁻¹ K⁻¹ depending on soil parent material, climatic setting, and particularly, soil-moisture variability. Results indicate that the standard industry practice to estimate thermal properties from soil type often leads to suboptimal GHEX design (i.e., GHEX design lengths were 44–52% longer than necessary to meet performance specifications). This research suggests that expanding the characterization of soil thermal properties in specific settings where HGHPs are targeted will improve understanding of the dynamic aspects of ground heat exchange and lead to more optimal HGHP system designs.