Fatigue evaluation in maintenance and assembly operations by digital human simulation

Virtual human techniques have been used a lot in industrial design in order to consider human factors and ergonomics as early as possible. The physical status (the physical capacity of virtual human) has been mostly treated as invariable in the current available human simulation tools, while indeed the physical capacity varies along time in an operation and the change of the physical capacity depends on the history of the work as well. Virtual Human Status is proposed in this paper in order to assess the difficulty of manual handling operations, especially from the physical perspective. The decrease of the physical capacity before and after an operation is used as an index to indicate the work difficulty. The reduction of physical strength is simulated in a theoretical approach on the basis of a fatigue model in which fatigue resistances of different muscle groups were regressed from 24 existing maximum endurance time (MET) models. A framework based on digital human modeling technique is established to realize the comparison of physical status. An assembly case in airplane assembly is simulated and analyzed under the framework. The endurance time and the decrease of the joint moment strengths are simulated. The experimental result in simulated operations under laboratory conditions confirms the feasibility of the theoretical approach

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

Background Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications. Methods We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC). Findings In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683–0·717]). Interpretation In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required. Funding British Journal of Surgery Society

The timing of color and location processing in the motor context.

International audienceIn this study, the use of color and location as stimulus attributes manipulated during a simple action was aimed at comparing how dorsal (location) and ventral (color) features are integrated in action and the timing of their processing. Eighteen subjects were presented with a green dot on a computer screen, which they were required to point at and touch. In 20% of the trials, the location or the color of the target was altered at the onset of movement to this stimulus, requiring the participant to modify the initially programmed response according to specific motor instructions. In the 'location-go' group, the target changed in location and participants were instructed to reach the displaced stimulus by correcting their ongoing movement. In the 'location-stop' and 'color-stop' groups, subjects were instructed to interrupt their movement when the target changed location or color, respectively. Results showed that the latency of the first responses to the perturbation clearly depended on the stimulus attribute and not on the motor instruction tested: the response to color change was obtained about 80 ms later than both conditions involving location change. It is concluded that: (1) color processing is slower than location processing, and (2) the first reactions to the location change occur after the same delay irrespective of the response required from the subject

Anomalous nucleation of gold nanoparticles on silicon substrate and monitoring the growth of ZnO nanowires on such structures

Nucleation of a gold catalyst on a (100) oriented silicon substrate was extensively investigated. An anomalous mechanism of nucleation was observed in the grain formation of gold nanoislands. The chemical vapour deposition method was employed to grow zinc oxide nanowires. Zinc powder and oxygen gas were used as reaction sources for the growth. Different shaped ZnO nanowires were obtained for different nucleation mechanisms. The nucleation mechanism and growth evolution were monitored by scanning electron microscopy and atomic force microscopy

Effects of magnetic and electric fields on the growth of carbon nanotubes using plasma enhanced chemical vapor deposition technique

Multiwalled carbon nanotubes are grown on nickel-seeded silicon substrates using plasma-enhanced chemical vapor deposition method at a temperature of 650 °C utilizing a mixture of acetylene and hydrogen. Magnetic and electric fields were used to obtain well-oriented carbon nanotubes. The direction of growth was found to strongly depend on the directions and magnitudes of the applied fields. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) have been used to investigate the grown nanotubes. The SEM and TEM images of as grown nanotubes show that applying magnetic field during the growth process affects the growth direction of the nanotubes and, furthermore, bent nanotubes can be achieved by changing the direction of the applied electric field alone. Raman spectroscopy has been used to analyze the structure of the samples.

Stimulus Location is Processed Faster than Stimulus Colour

There is a convergence of anatomical, electrophysiological, neuropsychological, and psychophysical data to support the dissociation of visual pathways into two main streams projecting from occipital to frontal cortex via the posterior parietal lobe (dorsal route) and via the inferotemporal lobe (ventral route). It is usually assumed that the dorsal route provides information that is useful for driving an action toward the stimulus (ie metric properties, such as localisation), whereas the ventral route extracts information useful for identifying it (ie intrinsic properties, such as colour). It is known that pointing movements can be reoriented to a novel target location within a short delay (about 110 ms), even when the target jump cannot be detected because of saccadic suppression. Electrophysiological studies have suggested that inputs to the dorsal pathway have a latency shorter than inputs to the ventral pathway. We compared latencies of visuomotor processing for colour and location during a pointing task. Target location and/or colour were altered upon movement onset. Instructions were to correct movement direction or to interrupt the movement according to the target change. We found that in both cases colour processing was slower (by about 100 ms) than location processing of the same target. Performance observed for identical movement speed was always higher for location responses whereas movement duration spontaneously chosen by subjects was longer when they had to process colour. Strikingly, corrections were also observed with the interruption instruction. We conclude that (1) colour is processed more slowly than location, and (2) automatic corrections can be observed prior to response inhibition for fast movements. </jats:p