Rainfall-runoff control: variably saturated transport for an infiltration system controlling water quality and quantity

Rainfall-runoff impacted by anthropogenic activities transports significant quantities of particulate, aqueous and complexed constituents. These diffuse, unsteady and stochastic event-based loadings are unique challenges for water quality and quantity control. The design, water quality and quantity functions of a partial exfiltration reactor (PER) utilizing Fe-coated-sand and porous pavement (CPP) is examined specifically across three representative rainfall-runoff events. Total concentrations and mass for metals (Zn, Pb, Cu and Cd), suspended solids, and Chemical oxygen demand were reduced significantly. Rainfall-runoff volume and peak flow were reduced and time to peak was extended. Influent dm/dp ratios based on particle analyses suggest that the dominant PER particle separation mechanisms were physical-chemical filtration with the CPP layer functioning as a straining surface. The performance of the PER is a function of the unsteady site hydrology with a particle mass-based concentration removal efficiency ranging from 71 to 96 %. A 2D numerical model with Richard¡¯s equation was used to simulate the effluent hydrograph and water content profiles under transient hydraulic loadings illustrating the water quantity and water quality function of the PER. The exfiltration capacity of the surrounding soil met limitation with bypass occurring, when simulated for 1, 2, and 5 year design storm events. Evaporation dominants the drying process in the top layer of the PER, which can be dried out in 2 days in summer. The role of saturation degree, ionic strength, and media characteristics in variably saturated filtration was examined by bench-scale experiment. The breakthrough of suspended particles decreased with decreasing water saturation degree and with increasing ionic strength. Variably saturated flow filtration was proved to be more efficient than saturated flow filtration for concrete media. A dimensionless surface tension number NST was introduced to extend a trajectory saturated filtration model to variably saturated porous media. The relationship between unsaturated hydraulic conductivity and water content was developed by fitting gravimetric measurement data to the van Genuchten equation. Good agreement with experimental data supports the conceptual basis of the trajectory model with a combined gas-liquid interface adsorption term in addition to the straining, interception, and sedimentation mechanisms of the trajectory model for saturated flow

Biomechanical Risk Assessment of Non-Contact Anterior Cruciate Ligament Injury in Taekwondo Athletes

Non-contact anterior cruciate ligament (ACL) injury can occur in many sports. It is interrelated with gender, anatomy, biomechanics, and neuromuscular control. Taekwondo athletes have a higher incidence of ACL injury than athletes from other sports. Objective: This study aimed to determine the biomechanical gender differences and mechanism of taekwondo athletes with ACL injury. Methods: A total of 28 taekwondo athletes (aged 14–19 years) were randomly selected and grouped by gender. Feet high floor, one foot high floor, and single leg squat were analyzed by a Vicon motion analysis system and Kistler 3D force platform for action. The knee joint angle and ground force were evaluated. Results: Results demonstrated biomechanical differences in knee joint between male and female athletes. Conclusion: ACL injury in taekwondo female athletes indicated the biomechanical mechanism of the knee joint, and it can be prevented by neuromuscular control training

Hybrids of Uniform Test and Sequential Uniform Designs with "Intersection" Method for Multi- objective Optimization

For multi-objective optimization under condition of complicated objective function, the data processing in the evaluation is sometime tediously long, special algorithm is needed to be adopted. Since the remarkable features of uniform distribution of test points within the test domain and the small number of tests, fully representative of each point, and easy to perform regression analysis, the uniform test design method is hybrid with the “intersection” method for multi-objective optimization to simplify the complicated data process in evaluation first. Furthermore, the "intersection" multi-objective optimization methodology is combined with sequential uniform design so as to get a more precise approximation for solving multi-objective optimization problem, the procedure for searching optimum of the “intersection“ multi-objective optimization methodology with sequential uniform design algorithm is put forward. A multi-objective optimization of linear programming problem with three variables is taken as our example, which involves a maximum for one objective and a minimum for another objective. The result for applying the novel approach to the example indicates the effectiveness of current hybrids

Hybrid of "Intersection" Algorithm for Multi-Objective Optimization with Response Surface Methodology and its Application

Recently, a new "intersection" method for multi-objective optimization was developed in the points of view set theory and probability theory, which introduces a new idea of favorable probability to reflect the favorable degree of the utility of performance indicator in multi-objective optimization, and the product of all partial favorable probabilities of entire utilities of performance indicators makes the overall / total favorable probability of the candidate. Here, in this paper, the new "intersection" algorithm for multi-objective optimization is combined effectively with response surface methodology (RSM) by taking each response as one objective, which transfers the multi-response optimization problem into a single response one with the help of the overall / total favorable probability of each scheme. The overall / total favorable probability is the uniquely decisive index of the scheme in the optimization. Applications of the hybrid approach with two examples in material technology are given, proper predictions are obtained

A New "Intersection" Method for Multi-Objective Optimization in Material Selection

Till now the previous methods for multi-objective optimization adopt the "additive" algorithm for the normalized evaluation indexes, which has the inherent shortcoming of taking the form of "union" in the viewpoint of set theory. In fact, "simultaneous optimization of multiple indexes" should be more appropriate to take the form of "intersection" for the normalized evaluation indexes in the respects of set theory and "joint probability" in probability theory. In this paper, a new concept of favorable probability is proposed to reflect the favorable degree of the candidate material in the selection; All material property indicators are divided into beneficial or unbeneficial types to the material selection; Each material property indicator correlates to a partial favorable probability quantitatively, and the total favorable probability of a candidate material is the product of all partial favorable probabilities in the viewpoints of "intersection" of set theory and "joint probability" in probability theory, which is the sole decisive index in the competitive selection process. Results of the application examples indicate the validity of the new method