Free-flow Systems Research Articles

System architecture and algorithms for detection, tracking and classification of vehicles in a free flow toll gantry using LiDARs

One of the most important functions in free-flow systems to be performed is the detection, classification and identification of vehicles at high and low speeds. In this sense, there are several technologies that fulfill this function such as 2D LiDARs and detection cameras, but these technologies can present difficulties such as their coverage area or in the case of cameras in changing conditions of visibility and luminosity, among others. The 3D LiDAR technology has demonstrated the ability to cover these limitations, but the processing of the captured data requires specific algorithms. The objective of this research paper is to develop robust algorithms for vehicle detection and classification using 3D LiDARs technology installed in the road infrastructure.

Spatio-Temporal Pattern and Influence Mechanism of Cultivated Land System Resilience: Case from China

The study of cultivated land systems from the perspective of resilience is of great significance for the innovation of the research paradigm of cultivated land use and the rational utilization and protection of cultivated land. This study aims to explain the theoretical connotations of cultivated land system resilience (CLSR), construct an evaluation system and zoning rules for CLSR, and take 30 provinces of China as case study areas to explore the influencing factors of CLSR, so as to provide a reliable governance plan for the sustainable development of cultivated land. The results show that: (1) CLSR refers to a sustainable development ability that CLS—by adjusting the structure and scale of internal elements—absorbs and adapts to internal and external disturbances and shocks to the maximum possible extent, abandons the original inapplicable state, creates a new recovery path, achieves a new balance, and avoids system recession. (2) The overall CLSR of the 30 provinces showed an upward trend, and the degree of polarization of the distribution pattern was gradually intensified and experienced a transition process from “leading by resource and ecological resilience—equilibrium of each resilience—leading by production and scale structural resilience”. (3) In the north, east, and south coastal areas of China, CLSR mainly consists of the major evolution areas and the stable development areas; the potential excitation areas of CLSR are mainly concentrated in the central and western regions of China; the CLSR-sensitive lag areas and degraded vulnerable areas are mainly distributed in the northwest and southwest of China. (4) Water resource endowment has a strong influence on CLSR, while social economy mainly influences CLSR through ‘economic foundation-superstructures’ and ‘economic development-factor agglomeration’. (5) According to the different CLSR zones, CLSR was strengthened mainly from the aspects of driving factor agglomeration, building factor free-flow systems, and multi-means support.

For whom the App Tolls

Direct, payment-by-car for tolling may still be some years away, but linking apps to existing free-flow systems is helping to streamline payments, lowering costs and enhancing customer experience and satisfaction.

A Framework Based on Finite Element Method (FEM) for Modelling and Assessing the Affection of the Local Thermal Weather Factors on the Performance of Anaerobic Lagoons for the Natural Treatment of Swine Wastewater

Anaerobic lagoons are natural wastewater treatment systems suitable for swine farms in small communities due to its low operational and building costs, as well as for the environmental sustainability that these technologies enable. The local weather is one of the factors which greatly influences the efficiency of the organic matter degradation within anaerobic lagoons, since microbial growth is closely related to temperature. In this manuscript, we propose a mathematical model which involves the two-dimensional Stokes, advection–diffusion-reaction and heat transfer equations for an unstirred fluid flow. Furthermore, the Anaerobic Digestion Model No1 (ADM1), developed by the International Water Association (IWA), has been implemented in the model. The partial differential equations resulting from the model, which involve a large number of state variables that change according to the position and the time, are solved through the use of the Finite Element Method. The results of the simulations indicated that the methodology is capable of predicting reasonably well the steady-state of the concentrations for all processes that take place in the anaerobic digestion and for each one of the variables considered; cells, organic matter, nutrients, etc. In view of the results, it can be concluded that the model has significant potential for the design and the study of anaerobic cells’ behaviour within free flow systems.

Development of a Self-regulated Bubble Irrigation System to Control the Size and Shape of Wetting Fronts

The main objectives of this study were to introduce a bubble irrigation system, compare the wetting fronts created by the bubble and free-flow systems, and test the viability of a bubble irrigation system. Two laboratory experiments were conducted using 2D flow to measure the wetting fronts. The first experiment measured the free-flow infiltration using an inverted, open plastic bottle. The second experiment tested the bubble-flow technique using an inverted, closed plastic bottle (ICPB). The results showed that the bubble-flow system created a larger width of wetting fronts at the beginning of the infiltration and then expanded less than that of the free-flow system. In contrast, the infiltration depth of the wetting fronts created by the bubble-flow system was much lower than that of the free-flow system. In conclusion, the wetting front width and depth in the bubble-flow system were slightly smaller than those in the free-flow system. In addition, the wetting fronts created by the ICPB were not moved upwards significantly, which proves the ability of specific distribution of the bubble-flow system on the wetting fronts. Therefore, the bubble irrigation system can be used as an alternative for distributing the moisture content in soil profiles.

Phytotoxicity Study of Native Plants in ex-mining lake water treatment

The use of phytoremediation in removing and degrade the contaminants gives great interest for researchers to explore further. This green technology is relatively eco-friendly and cost-effective. Before a full-scale system can be installed to ensure that the remedy is effective by selected plants using phytoremediation process, identification of these plants and its ability to resist toxicity of contaminants is crucial. In this study, the ability of native plants in Malaysia namely L. articulata, E. ochrostacys and E. dulcis to survive when exposed to acid mine drainage water (AMD) are investigated. This was done with free flow systems or free surface (FSF) for 30 days with water from ex mining lake, Tasik Puteri, Bukit Besi, Malaysia. The physical growth of those three plants such as height and withered leaves is monitored every seven day as indication of their survivability. Ferum (Fe) analysis is also carried out on the lower and upper part of the above three plants using Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES). Results of the Fe analysis showed that E.ochrostacys has the highest accumulation ability compared to E.dulcis and L. articulata with a maximum accumulation of 123,584 mg Fe/kg at lower part and 55,151 mg Fe/kg at the upper part. Furthermore, E. ochrostacys was also able to tolerate and survive in the water of Tasik Puteri up to 80% survival rate during phytotoxicity study.

Milk yield and milking station visits of primiparous versus multiparous cows on automatic milking system farms in the Upper Midwest United States

The objective of this study was to investigate milk yield and frequency of visits to the milking station of primiparous versus multiparous cows at different stages of lactation on farms with automatic milking systems (AMS) in the Upper Midwest United States. Forty farms were included in the study, and daily AMS software data were collected for 18 mo. For the investigation of milk yield and milking visits, stage of lactation was categorized into 14 periods, 7 d in length for the first 28 d in milk (DIM) and 30 d in length thereafter until 328 DIM. Cow traffic flow to the AMS (free or guided) was included in the model. For the evaluation of failures and refusals, stage of lactation was categorized into 6 periods, 7 d in length each for the first 28 DIM, and 2 periods of 150 d in length each thereafter until 328 DIM. Failures are milking station visits where a cow fails to be milked due to lack of machine attachment although it is time for the cow to be milked. Refusals are milking station visits before adequate time has passed since previous milking, thus the cow leaves the milking station without being milked. Data from lactation days beyond 328 DIM were excluded from the study. Primiparous cows in free-flow systems produced less milk than multiparous cows until the 11th stage of lactation and produced more milk from the 12th stage until the end of the study period. Primiparous cows in guided-flow systems produced less milk than multiparous cows all 14 stages of lactation, but were approaching the milk yield of multiparous cows at the end of the study period. This was a biologically normal lactation curve for primiparous cows. However, estimated peak ratio (primiparous vs. multiparous cows' peak milk yield) was lower than industry standards. Both traffic flow systems had fewer milking visits for primiparous cows compared with multiparous cows in early lactation. This lower milking frequency persisted until the 11th stage of lactation in free-flow systems. In guided-flow systems, primiparous cows were milked less frequently until the 5th stage of lactation, had similar milking frequency in the 6th stage of lactation, and were milked more frequently thereafter. Failures were greater for primiparous cows during all stages of lactation. However, the greatest differences were detected in the early stages of lactation. Primiparous cows had 0.067 more failures/cow per day on average than multiparous cows during wk 1 of lactation. For the remaining lactation stages, differences in failures ranged from 0.003 to 0.039. Refusals were less frequent (0.4 to 0.6/d) for primiparous cows during the first 2 wk of lactation, similar for wk 3 of lactation, and more frequent for the remaining lactation stages (0.10 to 0.14/d). Failures and refusals were only evaluated in free-flow systems. These findings appear to indicate a potential lagging performance for primiparous cows in early lactation as compared with multiparous cows. Additional investigation into improving the adaptation of primiparous cows to AMS in early lactation may be warranted.

Simulation of the Hydraulics and Treatment Performance of Horizontal Subsurface Flow Constructed Wetland Treating Greywater

Constructed wetlands (CWs) have evolved as some of reliable wastewater treatment technologies. Various types of CWs differ in their main design characteristics and in processes responsible for pollutant removal. Classification of CWS is based on the type of vegetation used and hydrological parameters involved and can thus be classified as free water surface or subsurface flow systems. Further, subsurface flow systems can be classified according to flow direction as vertical or horizontal. This study considers horizontal subsurface flow constructed wetlands (HSFCWs) which introduces the mechanistic, dynamic compartmental model-Constructed Wetlands 2D (CW2D). The model has successfully been utilized to evaluate the performance of vertical flow constructed wetlands and is being tested on HFCWs. An outdoor pilot scale HSFCW system was established in Nakuru, Kenya. CW2D was calibrated, validated and used to simulate hydraulic performance of HSFCW system. The model was used in predicting effluent concentrations of the main greywater pollutants. In general, the results obtained showed a good match with the measured data. CW2D is an effective tool for evaluating the performance of CWs and can provide insights in treatment problems at an existing CW. The same methodology can be used to optimize existing systems.

A new approach to hydraulic calculations of free-flow drainage systems

The accuracy of hydraulic calculations is determined by the accuracy of the mathematical models inherent in their foundation. The results of calculations, obtained by different models, and differing from each other by 5-10% is considered identical. The present study examines classical ways of finding the Chezy formula that are used for calculations of free-flow pipelines. These formulas differ from each other not only in parameters but also in the form of the functional dependence. The equation, underlying the hydraulic calculations, is nonlinear. Its solution is possible only in the number of well-established methods. It offers numerical computing to find pipelines diameters and their filling, as well as the algorithm to realize it. It conducts numerical experiment to compare pipelines diameters and filling and flow velocities. It presents frequency characteristics to distribute the parameters under analysis. For a specific example, the difference of cost of pipes, the diameters of which was found using the various formulas for coefficient Chezy, was calculated.

Multirate time integration for coupled saturated/unsaturated porous medium and free flow systems

A model formulation to describe fluid flows in coupled saturated/unsaturated porous medium and adjacent free flow regions is proposed. The Stokes equations are applied in the free flow domain, while the Richards equation is used to model the porous medium system. These two flow problems are coupled at the fluid-porous interface via an appropriate set of interface conditions. A multiple-time-step scheme is developed to solve the coupled problem efficiently. Numerical simulation results are presented for a model problem and a realistic setting that demonstrate the convergence and efficiency of the proposed computational algorithm. Time-splitting multistep methods can be successfully applied for modeling other physical systems where the processes evolve on different time scales, and these potential extensions are discussed.

A multiple-time-step technique for coupled free flow and porous medium systems

A mass conservative multirate time integration method is developed for a time-dependent isothermal single-phase free flow system coupled with an isothermal single-fluid-phase porous medium system. Long time stability of the proposed numerical scheme is proved under a time step restriction which depends on the physical parameters of the flow systems and the ratio between the time steps applied in the free flow and porous medium domains. Convergence analysis is carried out and a priori error estimates are obtained. Numerical results are presented for two model problems and a realistic setup. Advantages of using multiple-time-step techniques for modeling coupled systems where the processes evolve on different time scales are demonstrated and discussed.

Study of the effect of wind speed on evaporation from soil through integrated modeling of the atmospheric boundary layer and shallow subsurface.

In an effort to develop methods based on integrating the subsurface to the atmospheric boundary layer to estimate evaporation, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model was tested using experimental data to study the effect of wind speed on evaporation. The model consists of the coupled equations of mass conservation for two-phase flow in porous medium with single-phase flow in the free-flow domain under nonisothermal, nonequilibrium phase change conditions. In this model, the evaporation rate and soil surface temperature and relative humidity at the interface come directly from the integrated model output. To experimentally validate numerical results, we developed a unique test system consisting of a wind tunnel interfaced with a soil tank instrumented with a network of sensors to measure soil-water variables. Results demonstrated that, by using this coupling approach, it is possible to predict the different stages of the drying process with good accuracy. Increasing the wind speed increases the first stage evaporation rate and decreases the transition time between two evaporative stages (soil water flow to vapor diffusion controlled) at low velocity values; then, at high wind speeds the evaporation rate becomes less dependent on the wind speed. On the contrary, the impact of wind speed on second stage evaporation (diffusion-dominant stage) is not significant. We found that the thermal and solute dispersion in free-flow systems has a significant influence on drying processes from porous media and should be taken into account.

From Blood Vessels to Global Networks of Exchange: The Physiology of Benjamin Rush's Early Republic

IThis essay explores Benjamin Rush's ideas about physiology in an effort to revise current understandings of Rush's medico-political model and shed new light on conversations about circulation and sympathy in the early republic. Rush's non-hierarchical model of circulation broke with European medicine. For Rush, circulation was the key to corporeal and national health. Circulation needed to remain unfettered for individuals to realize republican promise and for the body to be properly invigorated—but free flow was problematic when it allowed information, goods, and bodies to flow unchecked. Sympathy was the secondary, essential mechanism that controlled this movement. Whereas circulation importantly opened both body and country to external stimuli, sympathy—physiological, social, political—managed responses to those stimuli, directing them along salubrious routes that were both natural and teachable. Rush himself worked tirelessly to mold these sympathies through rhetoric. This physiology and Rush's rhetorical medicine challenge the common understanding of Rush's "republican machines"; American bodies were, rather, dynamic living systems that could, through the cultivation of proper sympathies, become virtuous citizens. This essay extends current work on circulation by reconnecting it to physiology and suggesting that physiology's dynamism—rather than static "anatomy"—ought to inform discussions of the young nation. Rush knew bodies and nations were "tremendous oscillatory mass[es] of matter." America would maintain national health not by restricting circulation but by influencing citizens' reactions to free-flow systems that were only somewhat predictable and always dynamic. This physiology provides a new model for thinking about early American circulation and sympathy.

Elimination of estrogens and estrogenic activity from sewage treatment works effluents in subsurface and surface flow constructed wetlands

The effluents discharged from sewage treatment works (STWs) are major sources of environmental estrogens, which poses an urgent need to explore appropriate techniques for effluent-polishing. In light of the debate concerning the effectiveness of constructed wetlands (CW) for the elimination of estrogens, the present study evaluated and compared the performance of two basic types of CW, free water surface (FWS) and subsurface flow (SSF) systems. Two FWS and two SSF field CW mesocosms were fed continuously with an STW effluent. All the mesocosms provided an effective elimination of estrogens and estrogenic activity. Unexpectedly, the performance of FWS mesocosms was not inferior to that of SSF mesocosms. Additional shading experiments demonstrated that the presence of filamentous green algae along with the sunlight enhanced the removal of estrogens and estrogenic activity in FWS mesocosms, enabling FWS mesocosms to perform comparably to SSF mesocosms. Microbial inhibition tests further indicated that Spirogyra sp. itself rather than algae-attached bacteria played an important role in the removal of estrogen and estrogenic activity.

How to Bring the “Unseen” Proteome to the Limelight via Electrophoretic Pre-Fractionation Techniques

The present review reports a panoply of electrophoretic methods as pre-fractionation tools in proteomic investigations in preparation for mass spectrometry or two-dimensional electrophoresis map analysis. Such electrophoretic pre-fractionation protocols include all those electrokinetic methodologies which are performed in free solution, most of them relying on isoelectric focusing steps (although some approaches based on gels and granulated media are also discussed). Devices associated with electrophoretic separations are multi-chamber apparatuses, such as the multi-compartment electrolyzers equipped with either isoelectric membranes or with isoelectric beads, Off-Gel electrophoresis in a multi-cup device and the Rotofor, an instrument also based on a multi-chamber system but exploiting the conventional technique of carrier-ampholyte-focusing. Other free-flow systems, as well as miniaturized chambers, are also described.

Inventory of Constructed Wetlands in the United States

During 1990 and 1991 the U.S. Environmental Protection Agency (EPA) sponsored an effort to identify existing and planned constructed wetlands in the U.S., and to collect readily available information from operating systems. In addition to inquiries by telephone and mail, the effort included site visits to over 20 operating subsurface flow constructed wetlands. The inventory documented the presence of over 150 constructed wetland systems for wastewater treatment, including both free water surface (FWS) and subsurface flow (SF) systems. The majority of the systems identified were SF systems for treating municipal wastewater. FWS systems were separated into three groups based on the design level of effluent water quality. SF systems were separated into three groups based on the basic design approach. The inventory indicated that neither between nor within these groups was there consensus regarding basic hydraulic and engineering design criteria, system configuration, or any other aspect, such as type of vegetation, size and type of media, or pretreatment. Information on location, type of system, design approach, hydraulic and organic loading rates, costs, and other aspects is presented. Information gathered and "lessons learned" from the site visits are presented. Insufficient oxygen for nitrification appears to be a problem for both FWS and SF systems. Insufficient hydraulic design appears to be a problem for SF systems.

Uptake and Elimination of Poliovirus by West Coast Oysters

Accumulation of poliovirus Lsc-2ab by West Coast oysters was determined by using a stationary seawater system, and depuration was determined by using both stationary and free-flow systems. Results indicate that these shellfish have the same pattern of accumulation and localization of viruses as do East Coast species. However, uptake appeared to occur more rapidly than described for East Coast shellfish. There appeared to be a gradual diffusion of virus from the digestive area into the body. Depuration was found to occur more rapidly and completely under free-flow conditions than in a stationary system.

Uptake and Elimination of Poliovirus by West Coast Oysters

Accumulation of poliovirus Lsc-2ab by West Coast oysters was determined by using a stationary seawater system, and depuration was determined by using both stationary and free-flow systems. Results indicate that these shellfish have the same pattern of accumulation and localization of viruses as do East Coast species. However, uptake appeared to occur more rapidly than described for East Coast shellfish. There appeared to be a gradual diffusion of virus from the digestive area into the body. Depuration was found to occur more rapidly and completely under free-flow conditions than in a stationary system.

Combining Forced and Free Convective Equations to Represent Combined Heat-Transfer Coefficients for a Horizontal Cylinder

An analytical correlation of superposed free and forced convection for air for a horizontal cylinder in which the forced convection and free convection forces act in the same direction is considered. A simplified method by which the ordinary formulas for forced convection and for free convection can be used together to give the Nusselt number is presented. The method proposed herein can easily be modified to work for other combinations of free and forced flow systems. The method, therefore, may have wide application because standard formulas for simple systems are easily combined to obtain formulas which are valid for complicated systems.