High Volume Conditions Research Articles

Effect of Plow Pan on the Redistribution Dynamics of Water and Nutrient Transport in Soils

Plow pans are an essential part of the agricultural soil structure. By adjusting the soil bulk density and plow pan height, the water and nutrient transport are dynamically redistributed. Plow pans play a crucial role in promoting crop growth, increasing yields, and supporting sustainable land management. In this study, a column experiment was conducted to investigate the effects of plow pan height (10 cm and 15 cm) and bulk density (1.2, 1.4, and 1.6 g cm⁻3) on soil nutrient and water leaching under high-volume (HV) and low-volume (LV) fertilizer applications. The results reveal that the leachate volume decreased by 61.9% at a plow pan height of 10 cm and by 96.2% at a plow pan height of 15 cm when the bulk density was increased from 1.2 to 1.4 g cm⁻3 under HV conditions. There was no leachate when the plow pan bulk density was 1.6 g cm−3. The reserved concentration of alkali-hydrolyzable N in the plow pan soils was the highest when the plow pan had a bulk density of 1.4 g cm−3 and a height of 15 cm. However, when the plow pan height was 15 cm, the available P content in the plow pan soils decreased by 27.0% and 21.0% at bulk densities of 1.4 g cm⁻3 and 1.6 g cm⁻3, respectively, when compared with 1.2 g cm⁻3. Furthermore, the available P concentrations in the plow pan and subsoil layers decreased with an increase in the plow pan height. The available K concentrations in the topsoil decreased by 26.8% and 24.0% when the plow pan bulk density was increased from 1.2 to 1.4 g cm−3 at heights of 10 and 15 cm, respectively. Thus, the optimal plow pan height and bulk density are closely related to the types of soil nutrients. However, it is clear that excessively high bulk densities (e.g., 1.6 g cm−3) negatively impact soil properties. For different nutrient requirements, a bulk density of 1.2 or 1.4 g cm−3 can be chosen, with each providing suitable options based on the specific nutrient needs. This research offers practical insights into changes in nutrient adsorption and fixation in agricultural production associated with alterations in plow pan bulk density.

Postacute Care for Medicare Advantage Enrollees Who Switched to Traditional Medicare Compared With Those Who Remained in Medicare Advantage

Medicare Advantage (MA) plans receive capitated per enrollee payments that create financial incentives to provide care more efficiently than traditional Medicare (TM); however, incentives could be associated with MA plans reducing use of beneficial services. Postacute care can improve functional status, but it is costly, and thus may be provided differently to Medicare beneficiaries by MA plans compared with TM. To estimate the association of MA compared with TM enrollment with postacute care use and postdischarge outcomes. This was a cohort study using Medicare data on 4613 hospitalizations among retired Ohio state employees and 2 comparison groups in 2015 and 2016. The study investigated the association of a policy change with use of postacute care and outcomes. The policy changed state retiree health benefits in Ohio from a mandatory MA plan to subsidies for either supplemental TM coverage or an MA plan. After policy implementation, approximately 75% of retired Ohio state employees switched to TM. Hospitalizations for 3 high-volume conditions that usually require postacute rehabilitation were assessed. Data from the Medicare Provider Analysis and Review files were used to identify all hospitalizations in short-term acute care hospitals. Difference-in-difference regressions were used to estimate changes for retired Ohio state employees compared with other 2015 MA enrollees in Ohio and with Kentucky public retirees who were continuously offered a mandatory MA plan. Data analyses were performed from September 1, 2019, to November 30, 2023. Enrollment in Ohio state retiree health benefits in 2015, after which most members shifted to TM. Received care in an inpatient rehabilitation facility, skilled nursing facility, or home health, or any postacute care; the occurrence of any hospital readmission; the number of days in the community during the 30 days after hospital discharge; and mortality. The study sample included 2373 hospitalizations for Ohio public retirees, 1651 hospitalizations for other Humana MA enrollees in Ohio, and 589 hospitalizations for public retirees in Kentucky. After the 2016 policy implementation, the percentage of hospitalizations covered by MA decreased by 70.1 (95% CI, -74.2 to -65.9) percentage points (pp), inpatient rehabilitation facility admissions increased by 9.7 (95% CI, 4.7 to 14.7) pp, use of only home health or skilled nursing facility care fell by 8.6 (95% CI, -14.6 to -2.6) pp, and days in the community fell by 1.6 (95% CI, -2.9 to -0.3) days for Ohio public retirees compared with other Humana MA enrollees in Ohio. There was no change in 30-day mortality or hospital readmissions; similar results were found by comparisons using Kentucky public retirees as a control group. The findings of this cohort study indicate that after a change in retiree health benefits, most Ohio public retirees shifted from MA to TM and received more intensive postacute care with no significant change in measured short-term postdischarge outcomes. Future work should consider additional measures of postacute functional status over a longer follow-up period.

Achieving global surgical excellence: an evidence-based framework to guide surgical quality improvement programs in low and middle income countries.

There is a lack of evidence-based guidelines for enhancing global surgical care delivery. We propose a set of recommendations to serve as a framework to guide surgical quality improvement and scale-up initiatives in low and middle income countries (LMICs). From January-December 2019, we reviewed the available literature and their application toward LMIC settings. The first initiative was the establishment of Best Practices Recommendations intended to summarize best-level evidence around quality improvement processes that have shown to decrease morbidity and mortality in LMICs. The GRADE level of evidence and strength of the recommendation were assigned in accordance with the WHO handbook for guidelines development. The second initiative was the scale-up of principles and practices by establishing international expert consensus on the optimal organization of surgical services in LMICs using a modified Delphi methodology. Recommendations for three topic areas were established: reducing surgical site infections, improving quality of trauma systems, and interventions to reduce maternal and perinatal mortality. 27 studies were included in a quantitative synthesis and meta-analysis for interventions reducing surgical site infections, 27 studies for interventions improving the quality of trauma systems, and 14 studies for interventions reducing maternal and perinatal mortality. Using Delphi methodology, an international expert panel established consensus that district hospitals should place the highest priority on developing surgical services for low complexity, high volume conditions. At the national level, emergency and essential surgical care should be integrated within national Universal Health Coverage frameworks. This project fills a critical cap in the rapidly developing field of global surgery: gathering evidence-based, practical, and cost-effective solutions that will serve as a guide for the efficient planning and allocation of resources necessary to promote quality and safe essential surgical services in LMICs.

Priority of Emergency Vehicle Dynamic Right-Of-Way Control Method in Networked Environment

This paper proposes a dynamic right-of-way priority control approach for emergency vehicles (PDR-EVs) to improve their efficiency on basic road sections in the city based on a cooperative vehicle infrastructure system. Specifically, a movable physical function area was set in front of the EVs to prohibit connected vehicles (CVs) from entering a lane or to request them to change lanes to avoid a collision. Setting up a dynamic monitoring area at the EV’s front end affords real-time monitoring of the CV’s headway distribution in the inner lane. Moreover, a lane change request is sent when the CVs enter the buffer area, and the traversal search method predicts the optimal time and rate of speed to change the lane change and guides the CVs ahead of the EVs to merge into the target gap. Extensive simulations using the SUMO platform revealed that the priority of the dynamic right-of-way (PDR) control method reduced the average delay of the EVs by more than 70%, given that the road saturation did not exceed 0.8 and hardly increased the delay of the CVs (not more than 8%). Moreover, the simulations revealed that the long buffer area was suitable for low-volume conditions, and the short one was suitable for high-volume conditions. The proposed methodology fully employs the road space resources and enhances the EV’s operating efficiency on basic road sections while considering the CV’s operating efficiency.

Bi-level ramp merging coordination for dense mixed traffic conditions

Connected and Autonomous Vehicles (CAVs) hold great potential to improve traffic efficiency, emissions and safety in freeway on-ramp bottlenecks through coordination between mainstream and on-ramp vehicles. This study proposes a bi-level coordination strategy for freeway on-ramp merging of mixed traffic consisting of CAVs and human-driven vehicles (HDVs) to optimize the overall traffic efficiency and safety in congested traffic scenarios at the traffic flow level instead of platoon levels. The macro level employs an optimization model based on fundamental diagrams and shock wave theories to make optimal coordination decisions, including optimal minimum merging platoon size to trigger merging coordination and optimal coordination speed, based on macroscopic traffic state in mainline and ramp (i.e., traffic volume and penetration rates of CAVs). Furthermore, the micro level determines the real platoon size in each merging cycle as per random arrival patterns and designs the coordinated trajectories of the mainline facilitating vehicle and ramp platoon. A receding horizon scheme is implemented to accommodate human drivers’ stochastics as well. The developed bi-level strategy is tested in terms of improving efficiency and safety in a simulation-based case study under various traffic volumes and CAV penetration rates. The results show the proposed coordination addresses the uncertainties in mixed traffic as expected and substantially improves ramp merging operation in terms of merging efficiency and traffic robustness, and reducing collision risk and emissions, especially under high traffic volume conditions.

Design of Transit Signal Priority at Signalized Intersections with Queue Jumper Lanes

A queue jumper lane is a special bus preferential treatment that combines a short stretch of a special lane with a transit signal priority (TSP) to allow buses to bypass waiting queues of traffic and then to cut out in front of the queue by getting an early green signal. This paper first proposes a signal control design for queue jumper lanes with actuated TSP strategies and then compares its performance with that of the general actuated mixed-lane TSP. Different design alternatives were evaluated in the VISSIM microscopic simulation. The results show that the proposed TSP with queue jumper lanes can reduce more bus delays than can the commonly-used mixed-lane TSP, especially under high traffic volume conditions. It was also found that a nearside bus stop is superior to the far-side counterpart in terms of both bus delay and overall intersection delay for the proposed design.

Flow-level coordination of connected and autonomous vehicles in multilane freeway ramp merging areas

On-ramp merging areas are deemed to be typical bottlenecks for freeway networks due to the intensive disturbances induced by the frequent merging, weaving, and lane-changing behaviors. The Connected and Autonomous Vehicles (CAVs), benefited from their capabilities of real-time communication and precise motion control, hold an opportunity to promote ramp merging operation through enhanced cooperation. The existing CAV cooperation strategies are mainly designed for single-lane freeways, although multilane configurations are more prevailing in the real-world. In this paper, we present a flow-level CAV coordination strategy to facilitate merging operation in multilane freeways. The coordination integrates lane-change rules between mainstream lanes, proactive creation of large merging gaps, and platooning of ramp vehicles for enhanced benefits in traffic flow stability and efficiency. The strategy is formulated under an optimization framework, where the optimal control plan is determined based on real-time traffic conditions. The impacts of tunable model parameters on the produced control plan are discussed in detail. The efficiency of the proposed multilane strategy is demonstrated in a micro-simulation environment. The results show that the coordination can substantially improve the overall ramp merging efficiency and prevent recurrent traffic congestions, especially under high traffic volume conditions.

Various aspects of transition of care for adolescents with urological conditions.

Transition into adulthood is a common issue in many disciplines. However, urology faces additional difficulties due to different models of care and training as well as a wide diversity of pathologies. The goal of this paper is to discuss various aspects of the transition of urological care. This review provides some examples of pathologies that might require special attention of specialists. Most patients with rare diseases must be closely followed up in the long term. However, high-volume conditions may also have a huge impact on the well-being and quality of life in adulthood. Children who are cured due to oncological conditions will probably need additional attention in adulthood. The urological care during childhood is provided by a pediatric urologist, a pediatric surgeon or a urologist, depending on the local regulations and the organization of care. All patients are subsequently referred to a general urologist. Nowadays, a multidisciplinary approach is recommended in many cases, with a pediatric urologist as one of the team members. The patient, caregivers and healthcare professionals must be fully involved and focused on close cooperation to make the transition process smooth and successful.

Concurrent WIP and an application to clearing functions for complex heterogenous systems

Complex manufacturing systems are challenging to study because of the high level of information required and the inaccessibility of most of it. Their tractability is however essential for the efficiency of state-of-the-art industries. This is particularly the case in the semiconductor industry that faces high mix and low volume conditions, and for which traditional methods fail to capture the high complexity and require continuous actions and corrections to adjust to heterogeneous toolsets and product-mix.We present the Concurrent WIP (CWIP), a new way of studying such systems at the level of a process-cluster by identifying each job's queue from its own perspective. CWIP is designed to be practical, with a low level of resource investments, yet informative. We explain how CWIP can be computed based on historical data and then used to derive capacity estimates and clearing functions without any assumptions on the system or on the form of the functions. In the process, we derive not only an average workload-dependent capacity, but also a confidence interval on this capacity. The relevance and efficiency of the proposed estimates are experimentally tested on a simulated system mimicking a small but complex process-cluster of the semiconductor industry. The estimates are used to predict WIP absorption times and we show how they characterize well not only the average behavior but also the full range of possible behaviors of the system. Finally, we discuss further applications of CWIP, that could be used to compute refined clearing functions or to monitor complex systems.

Stochastic system dynamics modelling for climate change water scarcity assessment of a reservoir in the Italian Alps

Abstract. Water management in mountain regions is facing multiple pressures due to climate change and anthropogenic activities. This is particularly relevant for mountain areas where water abundance in the past allowed for many anthropogenic activities, exposing them to future water scarcity. Here stochastic system dynamics modelling (SDM) was implemented to explore water scarcity conditions affecting the stored water and turbined outflows in the Santa Giustina (S. Giustina) reservoir (Autonomous Province of Trento, Italy). The analysis relies on a model chain integrating outputs from climate change simulations into a hydrological model, the output of which was used to test and select statistical models in an SDM for replicating turbined water and stored volume within the S. Giustina dam reservoir. The study aims at simulating future conditions of the S. Giustina reservoir in terms of outflow and volume as well as implementing a set of metrics to analyse volume extreme conditions. Average results on 30-year slices of simulations show that even under the short-term RCP4.5 scenario (2021–2050) future reductions for stored volume and turbined outflow are expected to be severe compared to the 14-year baseline (1999–2004 and 2009–2016; −24.9 % of turbined outflow and −19.9 % of stored volume). Similar reductions are expected also for the long-term RCP8.5 scenario (2041–2070; −26.2 % of turbined outflow and −20.8 % of stored volume), mainly driven by the projected precipitations having a similar but lower trend especially in the last part of the 2041–2070 period. At a monthly level, stored volume and turbined outflow are expected to increase for December to March (outflow only), January to April (volume only) depending on scenarios and up to +32.5 % of stored volume in March for RCP8.5 for 2021–2050. Reductions are persistently occurring for the rest of the year from April to November for turbined outflows (down to −56.3 % in August) and from May to December for stored volume (down to −44.1 % in June). Metrics of frequency, duration and severity of future stored volume values suggest a general increase in terms of low volume below the 10th and 20th percentiles and a decrease of high-volume conditions above the 80th and 90th percentiles. These results point at higher percentage increases in frequency and severity for values below the 10th percentile, while volume values below the 20th percentile are expected to last longer. Above the 90th percentile, values are expected to be less frequent than baseline conditions, while showing smaller severity reductions compared to values above the 80th percentile. These results call for the adoption of adaptation strategies focusing on water demand reductions. Months of expected increases in water availability should be considered periods for water accumulation while preparing for potential persistent reductions of stored water and turbined outflows. This study provides results and methodological insights that can be used for future SDM upscaling to integrate different strategic mountain socio-economic sectors (e.g. hydropower, agriculture and tourism) and prepare for potential multi-risk conditions.

Simulation-based passenger evacuation optimization in metro stations considering multi-objectives

Evacuation is critical for safety management due to the highly overcrowded passengers in the metro stations. A simulation-based approach integrating Random Forest (RF) and Non-dominated Sorting Genetic Algorithm III (NSGA-III) is proposed to perform the evacuation evaluation and optimization at metro stations. A 3D model of the metro station is built to simulate the dynamic process of passenger evacuation in metro stations. A framework consisting of 9 influential factors and 3 objectives is developed to model the input-output relationship in passenger evacuation. An RF-based meta-model is used to construct the relationship between influential factors and objectives. At last, NSGA-III is applied to seeking the optimal solutions for the station renovation in order to achieve a safe evacuation. A station model simulating a real metro station in Singapore is constructed to test the effectiveness and applicability of the proposed approach. It is found that (1) A safe evacuation could be achieved for the station, but along with the increasing passenger volume and panic level, the requirement of evacuation objectives, the evacuation time and density, may not be met. Especially under the high passenger volume conditions, the passenger density could reach up to 6.2 unit/m2 (extremely dangerous); (2) An average improvement degree, 7.5%, can be achieved for the optimization of 20 test cases, and a maximum improvement degree, 22.5%, can be achieved for the evacuation optimization at metro stations; (3) It could be difficult to keep both of the evacuation time and density within the standards if one major exit is closed, even after the optimization. But a larger average improvement degree, 10.8%, can be achieved by the proposed optimization approach, which indicates the optimal solutions still could reduce the risk to a great extent. The novelty of this research lies in that (a) An RF algorithm is incorporated to build the meta-model that can properly represent the relationship between influential factors and objectives, despite the complexity and even conflicting between them; (b) Optimal measures for the evacuation improvement are provided from the MOO perspective by integrating NSGA-III. This hybrid approach can be used as a decision tool to assist regulatory authorities in developing effective emergency evacuation evaluation and optimization plans with adequate consideration of the complexity and multi-objective nature under evacuation events.

Optimal Trajectory Control for Left-Turn Vehicles at Exit Lane for Left-Turn Intersections

The exit lane for left-turn (EFL) intersection is a newly proposed unconventional intersection that can alleviate left-turn traffic congestion at intersections. The EFL design characteristic lies in that a part of exit lanes can be provisionally used as left-turn lanes to provide additional capacity for left-turn traffic. The inappropriate lane selection of human drivers decreases the effectiveness of such design. This paper establishes an optimal trajectory planning model for left-turn vehicles at EFL intersections under the automated driving environment. The longitudinal acceleration and lane changing variables are optimized simultaneously. The optimization model is formulated as a mixed-integer linear model, which ensures the computational efficiency. The effectiveness of the proposed model is explored under various traffic, geometric, and signal control conditions. The results show that the model can provide a suitable control strategy for left-turn vehicles. On average, traffic delay can be reduced by 47.3%. The proposed model has a promising control effect under high volume conditions. Moreover, the proposed model performs stably under the various length of the mixed-usage area.

Adaptation of Adult Pathways to Improve the Care of Adult Patients at Pediatric Hospitals.

Adaptation of Adult Pathways to Improve the Care of Adult Patients at Pediatric Hospitals.

Association of COVID-19 Hospitalization Volume and Case Growth at US Hospitals with Patient Outcomes

BackgroundWhether the volume of coronavirus disease 2019 (COVID-19) hospitalizations is associated with outcomes has important implications for the organization of hospital care both during this pandemic and future novel and rapidly evolving high-volume conditions. MethodsWe identified COVID-19 hospitalizations at US hospitals in the American Heart Association COVID-19 Cardiovascular Disease Registry with ≥10 cases between January and August 2020. We evaluated the association of COVID-19 hospitalization volume and weekly case growth indexed to hospital bed capacity, with hospital risk-standardized in-hospital case-fatality rate (rsCFR). ResultsThere were 85 hospitals with 15,329 COVID-19 hospitalizations, with a median hospital case volume was 118 (interquartile range, 57, 252) and median growth rate of 2 cases per 100 beds per week but varied widely (interquartile range: 0.9 to 4.5). There was no significant association between overall hospital COVID-19 case volume and rsCFR (rho, 0.18, P = .09). However, hospitals with more rapid COVID-19 case-growth had higher rsCFR (rho, 0.22, P = 0.047), increasing across case growth quartiles (P trend = .03). Although there were no differences in medical treatments or intensive care unit therapies (mechanical ventilation, vasopressors), the highest case growth quartile had 4-fold higher odds of above median rsCFR, compared with the lowest quartile (odds ratio, 4.00; 1.15 to 13.8, P = .03). ConclusionsAn accelerated case growth trajectory is a marker of hospitals at risk of poor COVID-19 outcomes, identifying sites that may be targets for influx of additional resources or triage strategies. Early identification of such hospital signatures is essential as our health system prepares for future health challenges.

Progress and Challenges in Industrially Promising Chemical Vapour Deposition Processes for the Synthesis of Large-Area Metal Oxide Electrode Materials Designed for Aqueous Battery Systems.

The goal of the battery research community is to reach sustainable batteries with high performance, meaning energy and power densities close to the theoretical limits, excellent stability, high safety, and scalability to enable the large-scale production of batteries at a competitive cost. In that perspective, chemical vapour deposition processes, which can operate safely under high-volume conditions at relatively low cost, should allow aqueous batteries to become leading candidates for energy storage applications. Research interest and developments in aqueous battery technologies have significantly increased the last five years, including monovalent (Li+, Na+, K+) and multivalent systems (Mg2+, Zn2+, Al3+). However, their large-scale production is still somewhat inhibited, since it is not possible to get electrodes with robust properties that yield optimum performance of the electrodes per surface area. In this review paper, we present the progress and challenges in the growth of electrodes through chemical vapour deposition at atmospheric pressure, which is one procedure that is proven to be industrially competitive. As battery systems attract the attention of many researchers, this review article might help those who work on large-scale electrical energy storage.

A multistage analytic model of the longitudinal and lateral acceleration during lane changing in work zone areas with the aid of a driving simulator experiment

ABSTRACT The problem of modelling the lane-changing process in work zone areas is important. This study proposed a multistage analytic model based on driving simulator experiment. Several scenarios under different traffic volumes and lane-ends sign positions are tested to collect the behavioral variables including distance, speed, and acceleration. Three successive stages covering the initiation part (including one stage) and action part (including two stages) are defined to depict driver’s acceleration patterns with mathematical formulations. The model reduces the complexity of depicting the lane-changing behavior by using critical acceleration variables. Meanwhile, some important conclusions were found. High traffic volume condition is more prone to aggressive driving behavior which reflected in larger longitudinal and lateral acceleration. Additionally, drivers closer to work zone tend to take an abrupt turning since less merging time and larger lateral acceleration were accepted. These findings are useful in work-zone planning and management.

The Impact of Emergency Parking Bays on Quasi-Eight-Lane Expressway Traffic Operations

Recently, with the discrepancy between increasing traffic demand and limited land resources, more and more expressways are choosing to use hard shoulders to expand into quasi-six-lane or quasi-eight-lane roads. Therefore, more emergency parking bays are used in place of traditional parking belts. However, there are no standards defining clear and unified specifications for the design of parking bays. This paper aimed to investigate the impact of emergency parking bays on expressway traffic operations with various traffic volumes and setting conditions. Based on the Monte Carlo method, VISSIM (Verkehr in Städten Simulation, a microscopic simulation software) simulation experiments were conducted using measured traffic operation data from one expressway in Zhejiang province. The probability of unsafe deceleration, lane-changing maneuvers and delay times were considered as the safety and efficiency indexes in this simulation study. The simulation results indicated that the emergency parking vehicle had an increasing impact on the following vehicle as the traffic volume increased. However, the impact pattern was found to be insensitive to the changing of the bay taper length. For low traffic volume, compared with the arrival vehicle, the departure vehicle had more impact on the traffic operation of the mainline. However, the impact of the arrival vehicle became more remarkable as the traffic volume increased. After parking, the waiting time for merging into the mainline was reduced as the volume decreased or as the bay taper increased. Furthermore, reductions caused by varying bay tapers were more significant under high volume conditions. Finally, this study suggests that parking bays are inapplicable when the occupancy of the road space exceeds 20% (about 3000 veh/h), because they would cause significant impact on the safety and efficiency of the expressway. The results of this paper are useful for the design and implementation of emergency parking bays.

Analysis of driver’s decision distance and merging distance in work zone area based on parametric survival models: With the aid of a driving simulator experiment

Work zones affect traffic safety and efficiency by changing the road condition and drivers’ maneuver. Therefore, it is important to fully understand drivers’ merging behavior in work zone related areas. In this study, a model framework composed of decision-distance analysis and merging-distance analysis was proposed, which could describe both decision-making and lane-changing process of merging behavior. A road environment with work zone was developed based on a driving simulator, and six scenarios composed of two levels of traffic volume and three different lane-end sign’s locations were designed. Forty-two licensed participants, including 21 females (10 professional drivers vs. 11 normal drivers) and 21 males (15 professional drivers vs. 6 normal drivers) finally completed the experiment. Based on the experimental data, parametric survival models were established to analyze the effects of traffic sign location, traffic situation and driver characteristics on drivers’ decision distance and merging distance. The results showed that: (i) the lane-end sign’s location affected the decision point of lane changing and further affected the merging distance. However, the effect was weakened when the sign was placed far away from the work zone; (ii) merging distance in high traffic volume condition was shorter than that in low traffic volume condition; (iii) work zone posed greater challenges for female drivers as they merged later than males, and females were reluctant to adjust their merging distance according to different gap conditions. The findings shed some light on the future improvement of traffic design and management in work zones.

Development and evaluation of a real-time pedestrian counting system for high-volume conditions based on 2D LiDAR

Automated monitoring of pedestrians on non-motorized facilities with high pedestrian flows is challenging. Several automated sensor solutions are commercially available that have been evaluated in the literature including traditional point-based sensors, such as inductive loop detectors for bicycles and infrared sensors for pedestrians. More recently, image-based systems, based on video cameras or thermal video cameras, have been developed. Despite the various options, some key limitations of existing solutions exist, in particular, the lack of low-cost solutions using embedded systems capable of performing in real-time under high volume (flow) conditions. This work aims at developing and evaluating the performance of a novel, real-time counting system, developed for environments with high pedestrian flows. The proposed system is based on emerging LiDAR (Light Detection and Ranging) technology. As an input, the system uses the distance measurements from a two-dimensional LiDAR sensor with a set of distinct laser channels and a given angular resolution between each channel. The developed system processes those measurements using a clustering algorithm to detect, count, and identify the direction of travel of each pedestrian. The system’s performance is evaluated by comparing its directional counting outputs with manual counts (ground truth) using disaggregate and aggregate (15-minutes interval) counts at two different monitoring locations. The results demonstrate that the system accurately counts more than 97% of the pedestrians at the disaggregate level, with a false direction detection rate of 1.1%. The over-counting error is 0.7% and the under-counting errors are 1.3% and 2.7% for the two selected sites. At the aggregate level (15-minutes interval), the average absolute percentage deviations (AAPDs) are 1.6% and 4.3% while the weighted AAPDs are 1.5% and 3.5% for the first and second sites, respectively. The accuracy of the proposed system is higher than the traditional technologies used for the same purpose.

Adaptation of vegetation in high-rate constructed wetland using artificial carriers for bacterial growth: Assessment using phytopathological indicators

A variant of constructed wetland using artificial carriers for bacterial growth as support medium (High Rate Constructed Wetlands (HRCW)) has been developed to depurate high organic loads (45 g BOD5 m−2 d-1). The metabolic state of vegetation in this phytodepuration system affects the treatment processes; therefore, its optimum adaptation is necessary. A comparative study, in mesocosms scale, was undertaken to test the capacity of adaptation of three plant species (Cyperus alternifolius, Heliconia burleana, and Zantedeschia aethiopica) in HRCW. 25 units of each species were planted in three lines of HRCW (one species per line), named for ease of understanding as L1, L2, L3 respectively, and monitored during the start-up phase of the system under climatic conditions of intersection between dry tropical forest and premontane sub-humid. Quantitative epidemiology was used to determine incidence, infection rate, and the relative area under the disease progress curve for each type of plant. The relationship between these epidemiology variables and the environmental conditions was determined. Vegetative stress was observed in all species, followed by a phase of high phytopathology, with infection rates of 0.0049-0.0183; 0.1085-0.1821; 0.0911-0.1158 (units/day) for L1, L2, and L3, respectively. The combination between the high organic load, water volume (94% v/v), and weather conditions favoured this behaviour. This study indicated that Cyperus alternifolius is a type of plant suitable for HRCW; highlighted the importance of studies on plant adaptation in CW with particular conditions; and showed epidemiological analysis as a tool for performing this selection in a low cost and user-friendly way.