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On lunar missions, efficient and safe transportation of human–robot systems is essential for the success of human exploration and scientific endeavors. Given the fact that transportation constructs bottlenecks for numerous typical lunar missions, it is appealing to investigate what function allocation strategies can generate optimal task implementation paths for robots with low-human workloads when the situation changes. Thus, this paper presents a novel approach to dynamic human–robot function allocation explicitly designed for team transportation in lunar missions. The proposed dynamic allocation framework aims to optimize human–robot collaboration by responding to existing and potential contingencies. First, a fitness concept model is designed to quantify the factors that motivate the functional adaptation of each agent in dynamic lunar mission scenarios. A hierarchical reinforcement learning (HRL) algorithm with two layers is then employed for decision-making and optimization of human–robot function allocation. Finally, the validity of the framework and algorithm proposed is validated by a series of human–robot function allocation experiments on a simulated environment that mimics lunar transportation scenarios, and is compared with the performance of other algorithms. In the future, path-planning algorithms can be incorporated into the proposed framework to improve the adaptability and efficiency of the human–robot function allocation in lunar missions.

Background Auxins play key roles in the phytohormone network. Early auxin response genes in the AUX/IAA, SAUR, and GH3 families show functional redundancy, which makes it very difficult to study the functions of individual genes based on gene knockout analysis or transgenic technology. As an alternative, chemical genetics provides a powerful approach that can be used to address questions relating to plant hormones. Results By screening a small-molecule chemical library of compounds that can induce abnormal seedling and vein development, we identified and characterized a piperazine compound 1-[(4-bromophenoxy) acetyl]-4-[(4-fluorophenyl) sulfonyl] piperazine (ASP). The Arabidopsis DR5::GFP line was used to assess if the effects mentioned were correlated with the auxin response, and we accordingly verified that ASP altered the auxin-related pathway. Subsequently, we examined the regulatory roles of ASP in hypocotyl and root development, auxin distribution, and changes in gene expression. Following ASP treatment, we detected hypocotyl elongation concomitant with enhanced cell elongation. Furthermore, seedlings showed retarded primary root growth, reduced gravitropism and increased root hair development. These phenotypes were associated with an increased induction of DR5::GUS expression in the root/stem transition zone and root tips. Auxin-related mutants including tir1–1, aux1–7 and axr2–1 showed phenotypes with different root-development pattern from that of the wild type (Col-0), and were insensitive to ASP. Confocal images of propidium iodide (PI)-stained root tip cells showed no detectable damage by ASP. Furthermore, RT-qPCR analyses of two other genes, namely, Ethylene Response Factor (ERF115) and Mediator 18 (MED18), which are related to cell regeneration and damage, indicated that the ASP inhibitory effect on root growth was not attributable to toxicity. RT-qPCR analysis provided further evidence that ASP induced the expression of early auxin-response-related genes. Conclusions ASP altered the auxin response pathway and regulated Arabidopsis growth and development. These results provide a basis for dissecting specific molecular components involved in auxin-regulated developmental processes and offer new opportunities to discover novel molecular players involved in the auxin response.

The mixed flow of pedestrians and cyclists is frequently observed on the roads they share, but investigations of the dynamics of this kind of mixed flow have been very limited. This study proposes a heuristic-based model to reproduce the mixed-flow dynamics of pedestrians and cyclists, and the model is calibrated with an experiment on the mixed traffic flow of pedestrians and cyclists. Pedestrians/cyclists were asked to walk/ride on a ring-shaped track. In the uni/bidirectional flow scenario, pedestrians and cyclists moved in the same/opposite direction. A genetic algorithm was used for parameter calibration. The model could reproduce the experimental results well. Under both scenarios, pedestrians and cyclists formed their own lanes. The pedestrians walked in the inner lane, and cyclists rode in the outer lane in a self-organized process. The widths of the pedestrian lane and the cyclist lane were found to be more uniform during bidirectional flow. The pedestrian flow rate was higher in the unidirectional flow scenario than in the bidirectional flow scenario. In contrast, at low cyclist densities, the cyclist flow rate was essentially the same in both scenarios. When the density was high, the cyclist flow rate is higher in the unidirectional flow scenario. Sensitivity analyses showed that cyclist speed had little effect on the pedestrian flow rate. A higher cyclist speed led to a higher cyclist flow rate at low densities, but the cyclist flow rates approached the same value at high cyclist densities. As the proportion of pedestrians/cyclists increased, the flow rate of cyclists/pedestrians decreased. The simulation results on a straight track were largely consistent with those on a ring-shaped track.

Wall-following is an important means for pedestrians to navigate during evacuation under limited visibility. Empirical and experimental results regarding wall-following behaviour are scarce in the ...

With the application of automation technology, Human operators rely on automation functions or intelligent agents to conduct complex cognitive tasks, but this also leads to a series of human factor risks such as out-of-the-loop and first failure problems. An appropriate level of automation (LOA) design will help to alleviate the above human factors risks and improve the performance of human-machine cooperation, but the traditional LOA taxonomy is difficult to directly guide the human-machine function allocation of operational supervisory tasks. To characterize current LOA design practices, a literature review was conducted to review the LOA taxonomy of supervision and control tasks in related fields. This research summarizes the taxonomy dimensions of LOA. The intelligent operational supervisory task requires the operators to maintain a high degree of interaction and cooperation with the automation system. Therefore, we must shift the focus of LOA design to cognitive interaction tasks and takeover tasks. This research analyzes the characteristics of different dimensions of LOA taxonomy in the literature, and summarizes the LOA granularity of system task, cognitive interaction task and takeover task. On this basis, from the perspective of human-machine interaction, the LOA taxonomy of intelligent operational supervisory tasks is proposed. This research provides an important theoretical basis for human-machine function allocation scheme and system LOA design, and has important theoretical and practical significance for improving the human-machine interaction efficiency.

Electrostatic levitation is an important method of studying material properties. Without using a container, a physical object is levitated between electrostatic plates and melted to the liquid state using a laser. Then, measurements are made via fast cooling or oscillation. Control technology is critical to the electrostatic levitation system. Uncertainty regarding the sample charge during the start-up and laser-melting periods often causes disturbances or causes levitation to fail. In this paper, we design a two-step adaptive control strategy with charge estimation and feed-forward control. This method can better adapt to charge uncertainty during the initial stage. In addition, we propose an innovative new method of superimposing oscillation signals via software to measure the material surface tension and viscosity. Unlike the traditional method, this approach does not require extra hardware resources and is flexible with regard to regulating the frequency and amplitude. A control system model with an accurate electric field model is established and used to simulate control progress in order to illustrate the advantage of our control method. Experiments based on a high-speed vision-servo system also validate the effectiveness of the adaptive and oscillation control strategies.

The efficiency of alighting and boarding plays an important role in station service level, train timetable making, etc. This paper proposes an improved social force model to investigate the effect of waiting area design at the metro platform on passengers’ alighting and boarding behaviors. Train timetable is considered for the description of the desired speed, and the desired direction is determined depending on different spatial partitioning of train door. Simulation results show that the design of waiting area indeed affects the alighting and boarding efficiency. With the change of civilization degree, and the number of boarding passengers and alighting passengers, the most frequently used type I waiting areas show more advantages than the type II waiting area in reducing the total travel time and the probability of deadlock in most conditions, which reflects that it would be best to adopt the type I waiting areas in the practical design. Moreover, the travel efficiency achieves the highest when passengers fully comply the rule of alighting first, which further indicates that compliance with civilized rules is more conducive to traffic and should be encouraged. This study can provide theoretical supports for the design of metro platform, thereby improving the station service level.

This paper investigates the neglected potential of carbon dioxide (CO2) emissions reduction from highway maintenance projects. Conventional assessment (CA) on fuel combustion of off-road equipment during maintenance, and a comprehensive life cycle assessment (LCA) on the materials production, fuel production, traffic delay and maintenance equipment were conducted for four typical maintenance schemes in a real highway project in China, through Microsoft spreadsheet models, VISSIM and CMEM model. The focus of the case study was to understand the magnitude and source of the gap of CO2 emissions assessment results between LCA and CA. In this study, we also checked scenarios that apply a few mitigation options from several industrial sectors in four typical maintenance schemes to investigate how significant potential for decarbonization of the highway maintenance might be neglected without using LCA. Results suggest that there exists an obvious gap between the total CO2 emissions per lane per kilometer of CA and that of LCA, and the gap is even up to 22 times of the CA results in this specific case study. Traffic delay caused by the lane closure has the largest contribution to the gap, while the shares of materials production and fuel production match. The scenarios analysis of mitigation strategies associated with the transport sector and other industrial sectors indicates that the LCA model could effectively identify the dominant inputs and CO2 emissions outputs of individual maintenance process in the complicated transport system, while CA may neglect or underestimate the potential for adopting some mitigation strategies, especially for mitigation options from other industrial sectors.

The mixed flow of bicycles and pedestrians is frequently observed on bicycle-pedestrian-shared roads. Unfortunately, studies on dynamics of this kind of mixed flow are very limited. This paper reports an experimental study of this kind of mixed traffic flow with equal numbers of pedestrians and cyclists asked to walk/ride in a ring-shaped track. In the uni-/bi-directional flow scenarios, pedestrians and bicycles moved in the same/opposite direction. Under both scenarios, bicycles and pedestrians formed their own lanes. Pedestrians walked in the inner lane and cyclists rode in the outer lane. Widths of both the pedestrian lane and the bicycle lane were more uniform in bidirectional flow. The pedestrian flow rate is larger in the unidirectional flow scenario than in the bidirectional flow scenario. In contrast, at low densities, the bicycle flow rate is essentially the same under the two scenarios. When the density is large, the bicycle flow rate becomes larger in the unidirectional flow scenario. Comparing the two modes, pedestrian flow rate is smaller/larger than bicycle flow rate at small/large densities under both scenarios.

Over the past decade, the rapid development of e-commerce and express industries in China has resulted in huge environmental costs. Compared with manufacturing industries, the values of green innovation are less recognized in logistics industries. To promote the green practices in logistic enterprises, it is imperative to have a thorough understanding of the determinants of green innovation adoption. To this end, this paper performs an empirical investigation into the intentions to adopt green innovation from 196 Chinese express companies. The determinant variables were constructed from the perspective of technology characteristics (perceived green usefulness and perceived integration ease of use), stakeholder pressure (government, customer, and platform pressures), and social influence. Then, a 20-item scale was designed based on the literature review and expert opinions. The results revealed the significant positive effects of technology characteristics and social influence on the intentions to adopt green innovation. Meanwhile, only the platform pressure was significant with the adopting intentions among the variables from stakeholder pressure. Moreover, variables from technology characteristics were found to have meditation effects between social influence and adopting intentions. Based on the findings, theoretical and practical implications are proposed to promote the green and sustainable development of express companies in China.

Additional file 10: Table S1 Sequences of primers used in RT-qPCR.

Children group are particularly vulnerable when exposed to a crowd as their cognitive ability and mobility are largely undeveloped, especially for pre-school children. Studies specifically designed to understand the movement dynamics of children pedestrians are scarce and their walking behaviors are less investigated and understood in the literature. As for the pre-school children, holding another child’s hand is usually a recommended pattern by their teachers when walking along a street or crossing a street for the sake of safety. In this study, we aim to investigate whether it also has a positive effect on children traffic efficiency. To achieve this goal, a series of controlled experiments were conducted with 80 pre-school children aged 4 ∼ 5 years old, in which they were required to walk normally and walk hand-in-hand. Two typical flow scenarios in a corridor, namely, the unidirectional flow and the bidirectional flow were considered. It was found that the traffic efficiency of children flow was reduced with the walking hand-in-hand pattern both in the unidirectional flow and the bidirectional flow. In addition, the typical characteristics of children walking hand-in-hand was investigated. It is expected that the datasets and findings from this study will be valuable resources to the researchers and pre-school educators to understand children walking behaviors and develop related educational programs to enhance traffic efficiency of children flow while maintaining safety during collective movement.

As an energy-efficient and healthy transport mode, bicycling has recently attracted the attention of governments, transport planners, and researchers. The dynamic characteristics of the bicycle flow must be investigated to improve the facility design and traffic operation of bicycling. We model the bicycle flow by using an improved Burgers cellular automaton model. Through a following move mechanism, the modified model enables bicycles to move smoothly and increase the critical density to a more rational level than the original model. The model is calibrated and validated by using experimental data and field data. The results show that the improved model can effectively simulate the bicycle flow. The performance of the model under different parameters is investigated and discussed. Strengths and limitations of the improved model are suggested for future work.

Cellular automaton (CA) approach has been widely used in pedestrian flow studies. However, one problem of CA approach is that gridlock usually occurs in counter flow. One possible reason is that CA...

Facing with the background of robotic arms teleoperation task, 11 items of performance metrics in operation were put forward, and an experiment of operating the simulated robotic arm to dock a target was carried out to testify the usability of these metrics. The experimental results show that: providing numerical information promotes several metrics, and the layout plan with 4 cameras is superior to 2 cameras on the metric of the times of reaching joint limitation; whether the mission could be successfully completed can be predicted by the times of reaching joint limitation, the times of incorrect operation and the efficiency of operating the hand controllers; the efficiency of operating the hand controller, which are put forward in this study, is able to predict the completion time and the risk of reaching joint limitation, hence it can be used in the evaluation of an operator’s ability in this robotic arm operation.

Cycling is a popular and sustainable mode of transportation. However, few studies have examined experimental and modeling studies on bicycle flow dynamics. In particular, for wide roads, the characteristics of high-density regimes in the fundamental diagram have not been well addressed, and the emergence of stop-and-go waves has not been fully understood. This study experimentally investigated bicycle flow dynamics on wide roads, using two types of 3-m-wide track. Different riding behaviors, namely, free riding, following, and overtaking, were analyzed. The bicycle flow dynamics were found to be essentially the same on the two tracks: (i) The bicycle flow rate remained nearly constant across a wide range of densities, in marked contrast to the single-file bicycle flow, which exhibited a unimodal fundamental diagram. By studying the weight density of the radial and lateral locations of cyclists, we argue that this behavior arises from the formation of more lanes with increase in global density. The newly formed lanes prevented the flow rate from decreasing. (ii) When the density exceeded 0.5 bicycles/m2, the flow rate began to decrease, and stop-and-go traffic emerged. Based on these behavioral observations, we propose an improved heuristic-based model to simulate bicycle flow on roads of different radii and explicitly account for the centrifugal effect of bicycles. The calibration and validation results demonstrate that the proposed model can reproduce the traffic dynamics of bicycle flow.

Crowd egress at narrow exit is a popular research topic, due to its intrinsic importance in architectural designs and building codes. However, relatively few studies have been conducted to verify the performance of pedestrian models for crowd escape at exits, especially relating to different exit designs. This paper aims to verify the applicability of a microscopic pedestrian simulation model, Social Force Model (SFM), embedded in Viswalk software to reproduce the effect of exit design on egress flow under normal and emergency conditions. Empirical data from controlled experiments considering the effects of obstacles size and location of exits under normal and emergency conditions were tested and compared with the simulation from the SFM. Results indicated that after parameter optimization, Viswalk simulation model can provide reasonable estimates for crowd escape under normal situations with a mean RMSE value 1.97s for total evacuation time. However, the simulation model was less capable in reproducing the emergency condition. As compared to the empirical data, clogging events were less spotted under emergency in the simulation. Faster-is-slower effects were not found in both empirical and simulation scenarios. In addition, the exit location effects from simulation data agreed with empirical data, corner exits were more efficient than middle exits under both situations. Meanwhile, the obstacle effects, as observed in empirical data, were less reproduced in the simulation, especially under emergency conditions. The results suggest that the application of the Viswalk model in simulating emergency situations needs scrutiny and further investigations in the future with empirical data.

Pedestrian evacuation dynamics under near zero or limited visibility conditions are usually different from normal evacuation conditions. In previous studies, the competitiveness of evacuees under limited visibility condition is mainly controlled by stimulating their physical and psychological states during evacuation, and the monetary incentive effect has not been investigated. This study aims to investigate the use of monetary incentive to mimic different emergency levels and the resulting effects in evacuation process under limited visibility condition. Two connected areas (7 m × 5 m) enclosed by an iron fence are set up for the single-exit evacuation experiment. A total of 18 evacuation experiments with 30 participants with limited vision were conducted. By controlling different amounts of monetary incentives as different emergency levels, the position of the connecting door in the middle or the edge of two fences and the opening of the exit of one room in two rooms were randomly selected as control variables to reduce the experimental behavior. The results show that the emergency level controlled by monetary incentive has a significant influence on evacuation efficiency. With the increase in incentive level, evacuation time of the participants generally decreased. The emergency level not only improved pedestrian’s walking speed by improving pedestrian’s urgency for evacuation, but also had a significant influence on pedestrian’s route choice. These results suggest that improving the incentive level can reduce the randomness and hysteresis of participants’ path and route selection decision. Findings of this study are valuable resources for proactive pedestrian crowd management under adverse conditions.

This paper studies pedestrian evacuation in view and hearing limited condition based on the social force approach. It is assumed that there are two types of pedestrians: Informed individuals know the exit location whereas uninformed individuals do not. The uninformed individuals can communicate with the informed ones within their perceptual fields, thus learning to know and memorize the exit location. We consider cases with and without communication/memory. The simulations show communication and memory are able to enhance the evacuation efficiency. We also investigate the impact of communication on the efficiency of an emergency exit.

The floor field cellular automaton model (FFCA) has been widely adopted to simulate pedestrian and evacuation dynamics. Many self-organized phenomena could be reproduced with the FFCA model, such as the lane formation in bidirectional pedestrian flow. However, as presented in this study, when we tried to use the FFCA model to simulate an experiment on bidirectional pedestrian flows performed in discrete space and time, we found the model failed to agree with the empirical results. The gridlock formation (not observed in the experiment) was unavoidable in the FFCA model and the clearance time in simulation was much larger than that of the experiment. From the experiments, we observed that people would like to stop if they would foresee a benefit in the near feature and consequently give way to people coming from the opposite direction. This inspired us to incorporate such behavioral rules for modeling pedestrian movements in bidirectional flows. To this end, we introduced a waiting time rule to the original FFCA model. Results showed the performance of the model could be significantly improved. The gridlock probability could be reduced to zero, with clearance time agreeing well with the experimental outcome. Findings from this study can provide meaningful insights for researchers into understanding the pedestrian behavior in bidirectional flow and help develop more reliable simulation software.

It is very important to use high-speed centrifugal pump with low specific instead of multi-stage high-pressure pump to reduce the volume of the whole marine reverse osmosis seawater desalination system. Based on the design model of high-speed centrifugal pump with low specific speed, we did a comparative study of 11 kinds of turbulence models with numerical simulation. Five methods (the convergent curves, calculation time step, characteristics curves, impeller fluid velocity and pressures, volute section surface streamline) are included to find the most suitable turbulence model. The results show that k-ε is the most suitable turbulence model to compare with design conditions and external characteristics, SST and RNG k-ε turbulence models appears more surface streamline details in the volute section.

For centrifugal fuel pump operating at high speed, the flow passage components in the pump will be more prone to cavitation, which may lead to efficiency decrease and failure. A single-stage high-speed centrifugal fuel pump is taken as the research object in order to study the phenomenon and the law of cavitation flow in this paper. The influence of different blade inlet angles, rotating speeds and fuel temperatures on cavitation of pump is then studied using numerical method. The results show that properly increasing the blade inlet angle can improve the cavitation performance, and at different rotational speeds, the degree of cavitation is determined not only by NPSHr, but also by Speed C of cavitation, however fuel temperature has rather small influence on the cavitation performance of the fuel pump.

A new type of marine reverse osmosis seawater desalination technology is developed in order to solve problems of high energy consumption, large volume and high noise, etc. in traditional one. The new process uses a medium pressure feed pump and a three-in-one circulating pump in series. The three-in-one pump serves as the high-pressure circulating pump, energy recycling device and booster pump. The pump can effectively recover the pressure energy in the process of reverse osmosis, so that the system energy consumption greatly reduced; the small configuration and integrated design of the device can adapt to the narrow space of the ship; the reciprocating frequency of the simplified system is low which means lower noise of the new system than the traditional one. The system can fully meet the requirements of miniaturization and energy saving of marine seawater desalination equipment.

Background: Although psoriasis occurs worldwide, the prevalence varies considerably between different peoples and regions. In China, a questionnaire-based study was carried out in 1987 and the prevalence of psoriasis was found to be 0.12%. Since then, no large-scale, population-based study has been reported. Objectives: To obtain the accurate figures for the prevalence of psoriasis in China. Methods: A population-based survey was conducted in 6 cities. The cluster sampling method was used to select communities in each city. The subjects were required to fill out self-reporting questionnaires during a face-to-face interview and also received physical examination by dermatologists. Results: 19,974 subjects were visited and 17,345 completed the questionnaires and received dermatological examination. 102 subjects (0.59%) were found to have psoriasis. After standardization, the prevalence of psoriasis was 0.47%. The prevalence of psoriasis in males and females was 0.54% and 0.44% respectively. 97.06% of the patients had psoriasis vulgaris. 28.43% of the patients reported a family history of psoriasis. 59.80% of patients experienced a negative influence on the quality of life. Conclusions: This population-based and dermatologist-confirmed study showed that the prevalence of psoriasis in China is 0.47%, which is higher than that reported in 1987.

This paper presents a behaviour based cellular automaton (CA) model for pedestrian counter flow. The behaviours of active slowing down and lane changing are considered to simulate the evolution of the pedestrian counter flow in a corridor with open boundaries. A concept of a dominant row is introduced to depict the pedestrian's lane changing behaviour. The velocity profile has been investigated and two separation times have been studied, which quantify the evolution process of the lane formation. The simulation shows that steady separate lanes can form even in dense conditions. Therefore, the gridlock formation has been remarkably suppressed.

Vitiligo is a common skin disease, the prevalence of which varies between races and countries. In China, no population-based study has been reported, although there have been some epidemiological studies on single cities or regions. The objective of this study was to obtain the prevalence and clinical profile of vitiligo in China. The study was conducted in 6 cities. Cluster sampling was used in selecting communities. Residents were visited at home and were asked to complete questionnaires and receive dermatological examinations. A total of 19,974 residents were visited and 17,345 valid questionnaires were obtained. The overall prevalence of vitiligo was 0.56%. Men were affected more than women (0.71% vs. 0.45%, p < 0.01). The prevalence of vitiligo increased with age. The most common type was focal vitiligo (36.1%). A positive family history was found in 9.8% of patients. Thirty-two percent of patients reported a negative impact of vitiligo on their quality of life.

Acne vulgaris is a common skin condition in adolescents. The prevalence of acne is thought to vary between ethnic groups and countries. A large-scale community-based study was performed in six cities in China to determine the prevalence and possible risk factors for acne in the Chinese population. A total of 17,345 inhabitants were included in this study. Of these, 1,399 were found to have acne. No acne was found in subjects under 10 years of age, and only 1.6% in the 10-year-old group had acne. Prevalence then increased rapidly with age, up to 46.8% in the 19-year-old group. After that, it declined gradually with age. Acne was rare in people over 50 years of age. In subjects in their late teens and 20s, acne was more prevalent in males, while in those over 30 years of age it was more prevalent in females. In subjects with acne, 68.4% had mild; 26.0% had moderate and 5.6% had severe acne. In adult acne, persistent acne was much more common (83.3%) than late-onset acne (16.7%). Smoking and drinking were found to be associated with adolescent acne, while no association was found between diet and acne. These results suggest that the prevalence of acne in the Chinese population is lower than that in Caucasian populations, and that adult acne is not uncommon in Chinese subjects.