Average Loading Rate Research Articles

Ability of sagittal kinematic variables to estimate ground reaction forces and joint kinetics in running.

Controlled laboratory study, cross-sectional design. To determine if sagittal kinematic variables can be used to estimate select running kinetics. Excessive loading during running has been implicated in a variety of injuries, yet this information is typically not assessed during a standard clinical examination. Developing a clinically feasible strategy to estimate ground reaction forces and joint kinetics may improve the ability to identify those at an increased risk of injury. Three-dimensional kinematics and ground reaction forces of 45 participants were recorded during treadmill running at self-selected speed. Kinematic variables used to estimate specific kinetic metrics included vertical excursion of the center of mass, foot inclination angle at initial contact, horizontal distance between the center of mass and heel at initial contact, knee flexion angle at initial contact, and peak knee flexion angle during stance. Linear mixed-effects models were fitted to explore the association between the kinetic and kinematic measures, including step rate and sex, with final models created using backward variable selection. Models were developed to estimate peak knee extensor moment (R(2) = 0.43), energy absorbed at the knee during loading response (R(2) = 0.58), peak patellofemoral joint reaction force (R(2) = 0.55), peak vertical ground reaction force (R(2) = 0.48), braking impulse (R(2) = 0.50), and average vertical loading rate (R(2) = 0.04). Our findings suggest that insights into important running kinetics can be obtained from a subset of sagittal plane kinematics common to a clinical running analysis. Of note, the limb posture at initial contact influenced subsequent loading patterns in stance.

Influence of inoculum on growth and retention of the biomass in anaerobic filters

In this study we evaluated, on bench scale, two anaerobic filters of equal configuration and using coconut shell as support material, for the treatment of the wastewater generated in cassava’s starch extraction process. Considering that in the study area the inoculum available in enough quantity is cow manure, this inoculum was used alone (Reactor 1) and mixed with granular sludge in a ratio of 1:1 (Reactor 2). The influence of inoculum was evaluated in the performance of the anaerobic filters as well as in the biomass adaptation to the substrate and the prevalent growth on support material. Both reactors showed potential for the treatment of this type of wastewater, with a Hydraulic Retention Time (HRT) of 12 hours, an average Organic Loading Rate (OLR) of 7.0 kg COD/m3*d and a Buffer Index (BI) that varied from 0.20 to 0.35. The increase up to 50% in the Specific Methanogenic Activity (SMA) at the end of the start-up in both reactors, confirmed the adequate biomass adaptation to the substrate as a result of the control of buffer capacity, and the higher values in the R2, showed that cow manure mixed with granular sludge improved methane production and process efficiency. It was found that the occluded biomass had greater activity than the attached one; this showed that the support material allowed the development of a greater proportion of active biomass within the interstices.

Effects of dynamic operating conditions on nitrification in biological rapid sand filters for drinking water treatment

Biological rapid sand filters are often used to remove ammonium from groundwater for drinking water supply. They often operate under dynamic substrate and hydraulic loading conditions, which can lead to increased levels of ammonium and nitrite in the effluent. To determine the maximum nitrification rates and safe operating windows of rapid sand filters, a pilot scale rapid sand filter was used to test short-term increased ammonium loads, set by varying either influent ammonium concentrations or hydraulic loading rates. Ammonium and iron (flock) removal were consistent between the pilot and the full-scale filter. Nitrification rates and ammonia-oxidizing bacteria and archaea were quantified throughout the depth of the filter. The ammonium removal capacity of the filter was determined to be 3.4 g NH4–N m−3 h−1, which was 5 times greater than the average ammonium loading rate under reference operating conditions. The ammonium removal rate of the filter was determined by the ammonium loading rate, but was independent of both the flow and influent ammonium concentration individually. Ammonia-oxidizing bacteria and archaea were almost equally abundant in the filter. Both ammonium removal and ammonia-oxidizing bacteria density were strongly stratified, with the highest removal and ammonia-oxidizing bacteria densities at the top of the filter. Cell specific ammonium oxidation rates were on average 0.6 × 102 ± 0.2 × 102 fg NH4–N h−1 cell−1. Our findings indicate that these rapid sand filters can safely remove both nitrite and ammonium over a larger range of loading rates than previously assumed.

First stage of the French vertical flow constructed wetland system: experiments with the reduction of surface area and number of units

Small vertical-flow constructed wetland units comprising the first stage of the French system were studied in Brazil for the treatment of raw sewage. Planted and unplanted units and different feeding strategies were tested. In the first phase, hourly batches of a daily flow of 13 m3 d−1 were applied over three alternating units, resulting in an average hydraulic loading rate (HLR) on the full system of 0.15 m3 m−2 d−1. A second phase, aimed at reducing land requirements, kept the same daily flow and batch frequency, but used two alternating units, resulting in a HLR on the full system of 0.22 m3 m−2 d−1. Removal efficiencies were very good when the system operated with three units, with mean values of 82% for biochemical oxygen demand (BOD), 81% for chemical oxygen demand (COD), 85% for total suspended solids (TSS) and 59% for NH4+-N. With two units, the equivalent values were 74% for BOD, 59% for COD, 67% for TSS and 51% for NH4+-N. There were significant differences in the median removal efficiencies of COD and TSS. No significant differences were found between planted and unplanted units for most constituents. In both phases, the overall good performance and the simplicity of the system make this treatment process a very attractive alternative for developing countries.

Influence of soil physical parameters on removal efficiency and hydraulic conductivity of vertical flow constructed wetlands

Low cost filter materials for efficient waste water treatment in constructed wetlands are worldwide in demand. However, information on soil physical parameters needed for efficient treatment is scarce. We investigated 5 different lava and one fluviatile operating sand filters in Germany for their differences in pore size distribution spectra, specific inner surface area and cumulative pore volume. While these soil physical parameters did have an influence on purification capacity and hydraulic conductivity, differences in mineralogy (presence of zeolites), waste water distribution systems (baffle plates versus pipes) and loading rates were the dominating factors determining filter efficiency. Lava sands convince with high purification capacities during permanent loading rates of >100mmd−1, average loading rates of 20gCODm−2d−1 (chemical oxygen demand) and approximate effective loading rates of up to 250gCODm−2d−1.

Reduction in ground reaction force variables with instructed barefoot running

BackgoundBarefoot (BF) running has recently increased in popularity with claims that it is more natural and may result in fewer injuries due to a reduction in impact loading. However, novice BF runners do not necessarily immediately switch to a forefoot strike pattern. This may increase mechanical parameters such as loading rate, which has been associated with certain running-related injuries, specifically, tibial stress fractures, patellofemoral pain, and plantar fasciitis. The purpose of this study was to examine changes in loading parameters between typical shod running and instructed BF running with real-time force feedback. MethodsForty-nine patients seeking treatment for a lower extremity injury ran on a force-sensing treadmill in their typical shod condition and then BF at the same speed. While BF they received verbal instruction and real-time feedback of vertical ground reaction forces. ResultsWhile 92% of subjects (n = 45) demonstrated a rearfoot strike pattern when shod, only 2% (n = 1) did during the instructed BF run. Additionally, while BF 47% (n = 23) eliminated the vertical impact transient in all eight steps analyzed. All loading variables of interest were significantly reduced from the shod to instructed BF condition. These included maximum instantaneous and average vertical loading rates of the ground reaction force (p < 0.0001), stiffness during initial loading (p < 0.0001), and peak medial (p = 0.001) and lateral (p < 0.0001) ground reaction forces and impulses in the vertical (p < 0.0001), medial (p = 0.047), and lateral (p < 0.0001) directions. ConclusionAs impact loading has been associated with certain running-related injuries, instruction and feedback on the proper forefoot strike pattern may help reduce the injury risk associated with transitioning to BF running.

Simultaneous organic carbon and nitrogen removal in an anoxic-oxic activated sludge system under various operating conditions.

This study investigated a bench-scale anoxic-oxic activated sludge system for integrated removal of COD and nitrogen. The experimental unit includes four chambers and continuous feeding in first chamber without recycle of nitrified liquid from aerobic to anoxic chamber unlike the conventional anoxic-oxic process. Recycled excessive sludge was used for the purpose of recycling nitrified mixed liquor. Synthetic wastewater with average loading rates of 0.53 kg COD/m(3)/d and 0.067 kg NH4(+)-N/m(3)/d was fed to the reactor system at hydraulic residence times (HRT) of 24 and 18 h. The results of 100 days operation showed high removal efficiencies of organic matter of about 97% as total COD and more than 99% removal of ammonia-nitrogen. In anoxic-oxic operation phase, total inorganic nitrogen (TIN) removal was about 66% by pre-denitrification. Moreover, the solid liquid separation through final clarifier was excellent without any suspended solid in the effluent.

A two-stage heuristic method for vehicle routing problem with split deliveries and pickups

The vehicle routing problem (VRP) is a well-known combinatorial optimization issue in transportation and logistics network systems. There exist several limitations associated with the traditional VRP. Releasing the restricted conditions of traditional VRP has become a research focus in the past few decades. The vehicle routing problem with split deliveries and pickups (VRPSPDP) is particularly proposed to release the constraints on the visiting times per customer and vehicle capacity, that is, to allow the deliveries and pickups for each customer to be simultaneously split more than once. Few studies have focused on the VRPSPDP problem. In this paper we propose a two-stage heuristic method integrating the initial heuristic algorithm and hybrid heuristic algorithm to study the VRPSPDP problem. To validate the proposed algorithm, Solomon benchmark datasets and extended Solomon benchmark datasets were modified to compare with three other popular algorithms. A total of 18 datasets were used to evaluate the effectiveness of the proposed method. The computational results indicated that the proposed algorithm is superior to these three algorithms for VRPSPDP in terms of total travel cost and average loading rate.

Landing pattern and vertical loading rates during first attempt of barefoot running in habitual shod runners

There is evidence supporting that habitual barefoot runners are able to disperse impact loading rates by landing pattern modification. Yet, case studies suggested that barefoot running may result in severe running injuries, such as metatarsal and calcaneal stress fractures. Injuries may be due to a difference in biomechanical response between habitual and novice barefoot runners. This study investigated the initial effects of barefoot running in habitual shod runners in terms of landing pattern modification and vertical loading rates. Thirty habitual shod runners (mean age 25.5±5.2years; 18 men; with a minimum running mileage of 30km per week for at least one year) ran on an instrumented treadmill at 10km/h shod and barefoot in a randomized order. Vertical average (VALR) and instantaneous loading rates (VILR) were obtained by established methods. Landing pattern was presented as a ratio between the number of footfalls with a heelstrike and the total step number. Twenty participants demonstrated an automatic transition to a non-heelstrike landing during barefoot running, whereas a mixed landing pattern was observed in 10 participants. Compared to shod running, both VALR and VILR were significantly reduced during barefoot running (p<.021). In the subgroup analysis, VALR for the shod condition was significantly higher than barefoot running, regardless of the landing pattern. VALR for the non-heelstrike pattern during barefoot running was significantly lower than participants with a mixed landing pattern. Conversely, we observed two participants who completely altered their landing patterns, presented high VALR and VILR values. Habitual shod runners presented lower loading rates during barefoot running but their landing pattern transitions were not uniform. Novice barefoot runners with a mixed landing pattern may sustain higher loading rates, compared with those who completely avoided heelstrike pattern. However, a complete landing pattern modification may not guarantee lower loading rates.

Semi-continuous anaerobic co-digestion of cow manure and steam-exploded Salix with recirculation of liquid digestate

The effects of recirculating the liquid fraction of the digestate during mesophilic anaerobic co-digestion of steam-exploded Salix and cow manure were investigated in laboratory-scale continuously stirred tank reactors. An average organic loading rate of 2.6 g VS L−1 d−1 and a hydraulic retention time (HRT) of 30 days were employed. Co-digestion of Salix and manure gave better methane yields than digestion of manure alone. Also, a 16% increase in the methane yield was achieved when digestate was recirculated and used instead of water to dilute the feedstock (1:1 dilution ratio). The reactor in which the larger fraction of digestate was recirculated (1:3 dilution ratio) gave the highest methane yields. Ammonia and volatile fatty acids did not reach inhibitory levels, and some potentially inhibitory compounds released during steam explosion (i.e., furfural and 5-hydroxy methyl furfural) were only detected at trace levels throughout the entire study period. However, accumulation of solids, which was more pronounced in the recycling reactors, led to decreased methane yields in those systems after three HRTs. Refraining from the use of fresh water to dilute biomass with a high-solids content and obtaining a final digestate with increased dry matter content might offer important economic benefits in full-scale processes. To ensure long-term stability in such an approach, it would be necessary to optimize separation of the fraction of digestate to be recirculated and also perform proper monitoring to avoid accumulation of solids.

Kinematic and Kinetic Comparison of Running in Standard and Minimalist Shoes

The purpose of this study was to determine whether running in a minimalist shoe results in a reduction in ground reaction forces and alters kinematics over standard shoe running. The secondary purpose of this study was to determine whether within-session accommodation to a novel minimalist shoe occurs. Subjects were 14 male, rearfoot striking runners who had never run in a minimalist shoe. Subjects were tested while running 3.35 m·s(-1) for 10 min on an instrumented treadmill in a minimalist and a standard shoe as three-dimensional lower extremity kinematics and kinetics were evaluated. Data were collected at minute 1 and then again after 10 min of running in both shoe conditions to evaluate accommodation to the shoe conditions. Shoe-time interactions were not found for any of the variables of interest. Minimalist shoe running resulted in no changes in step length (P = 0.967) or in step rate (P = 0.230). At footstrike, greater knee flexion (P = 0.001) and greater dorsiflexion angle (P = 0.025) were noted in the minimalist shoe. Vertical impact peak (P = 0.017) and average vertical loading rate (P < 0.000) were greater during minimalist shoe running. There were main effects of time as dorsiflexion angle decreased (P = 0.035), foot inclination at footstrike decreased (P = 0.048), and knee flexion at footstrike increased (P = 0.002), yet the vertical impact peak (P = 0.002) and average vertical loading rate (P < 0.000) increased. Running in a minimalist shoe appears to, at least in the short term, increase loading of the lower extremity over standard shoe running. The accommodation period resulted in less favorable landing mechanics in both shoes. These findings bring into question whether minimal shoes will provide enough feedback to induce an alteration that is similar to barefoot running.

Air Cargo Domestic Route Designing of China

For finding a way of air cargo route designing method, statistical analysis, multiple linear regression analysis and cluster analysis with SPSSS program are used in this article. After choosing sample flight segment with SWORT analysis method, this article uses lots of data to determine the indicator of route designing especially from the point of airline profit. Then using cluster analysis to get the airport classification and using hub-airport route network designing to get the model of air cargo domestic route network of China. The new and original thing is that this article uses average load rate as one of the evaluation indicator.

Part of the Town Sewage Treatment Plants Investigation and Analysis of Current Situation of Guizhou Province

Guizhou province has built 66 town sewage treatment plants, the statistics of the construction, operation, and energy consumption statistics show that town sewage treatment plants in Guizhou are based on small ones below 10,000 m3 / d ,the common treating process is mostly oxidation ditch.Most of the A / O process and HASN craft, pipe network are mostly mixed-flow, the average load rate of sewage treatment plants is 76.87 percent. Microwave treatment process is the most efficient way to remove COD and SS, biological aerated filter is the most efficient way to remove BOD and ammonia, activated sludge process is the best way to remove phosphorus. With the increasing scale of the operating, costs are reduced, so sewage treatment plants should choose technology and scale to adapt to local conditions, improve the operation of the facility and enhance the pollutant removal rate effectively.

Mathematical modeling of bio-hydrogen production from starch wastewater via up-flow anaerobic staged reactor

Hydrogen production from starch wastewater industry via up-flow anaerobic staged reactor was investigated. The reactor was operated at an average organic loading rate of 13.17 ± 8.35g COD/L d and hydraulic retention time of 8 h. The reactor achieved chemical oxygen demand (COD) and carbohydrate removal efficiencies of 84 and 92%, respectively. The total volatile fatty acids increased from 58.5±30.0 (influent) to 235.6±190.8 mg/L in the treated effluent, indicating that acidogenesis bacteria were dominant in the reactor. The system achieved maximum hydrogen production rate (HPR) and hydrogen yield of 2.48 L H2/d and 8.8 mL H2/g CODremoved, respectively. Simulated model tracks the experimental data with a correlation coefficient (R2 = 0.893). Maximum substrate utilization rate (μmax,s) and maximum volumetric HPR (μmax,h) were calculated at different food to micro-organisms (F/M) ratios of 0.15, 0.31, 0.46, 0.62, and 0.93g COD/g VSS. Results showed that μmax,s increased to −0.76g COD/L h at F/M ratio of 0.46, and then remained relatively constant at a value of −0.68g COD/L h. Similar trends were observed for HPR, where it peaked (μmax,h of 93.89 mL H2/h) at F/M ratio of 0.46.

Clogging reduction and removal of hormone residues with laboratory-scale vertical flow organic-based filter and hybrid wetland

A laboratory-scale, intermittently fed, organic-based vertical flow filter was tested as a pre-treatment of high-strength urban wastewater to reduce the risk of clogging in treatment wetlands. At an average hydraulic loading rate of 815 L/m2 day and average surface loading rates of biological oxygen demand of 458 g/m2 day, chemical oxygen demand of 594 g/m2 day and suspended solids of 310 g/m2 day, the organic-based vertical flow filter achieved removal efficiencies of 48 % of biological oxygen demand, 45 % of chemical oxygen demand, 69 % of suspended solids and 51 % of turbidity. For this unit, removals were significantly correlated with organic surface loading rates but not with hydraulic loading rate. Additionally, the organic-based vertical flow filter removed almost completely the hormone residues studied: estrone, 17β-estradiol, 17β-ethynyl estradiol, diethylstilbestrol, estriol, norethisterone and testosterone, most probably by the combination of adsorption onto the organic substrate and biodegradation. The efficiency of the combined system was remarkable for biological oxygen demand (97 %), chemical oxygen demand (89 %), suspended solids and turbidity (99 %), fecal coliforms and E. coli (99.9 %) and fecal enterococci (99 %).

Pilot-scale nitrogen removal from leachate by ex situ nitrification and in situ denitrification in a landfill bioreactor

A combined process consisting of ex situ nitrification and in situ denitrification in landfill refuse was studied in pilot scale for nitrogen removal from municipal landfill leachate. The results showed that above 80% of partial nitrification ratio and an average COD loading rate of 1.50kgm−3d−1 were steadily maintained under DO concentrations of 1.0–1.7mgL−1 in the aerobic reactor. Quantitative PCR results indicated that nitrite-oxidizing bacteria being sensitive to DO fluctuations lead to partial nitrification when free ammonia inhibition was weak. Nitrified landfill leachate could be denitrified in the landfill bioreactor with maximum total oxidizing nitrogen removal rate of 67.2gNt−1TSwasted−1. Clone and sequencing analysis of denitrifying bacterial nirS gene inferred that heterotrophic denitrifier Azoarcus tolulyticu was the primary nitrogen converter in the landfill bioreactor. The obtained results will provide valuable information for optimizing the design and operation of a landfill bioreactor.

Developing a Multiobjective Optimization Scheduling System for a Screw Manufacturer: A Refined Genetic Algorithm Approach

Over time, the traditional single-objective job shop scheduling method has grown increasingly incapable of meeting the requirements of contemporary business models; thus, a multiobjective scheduling solution is required. Because of changing orders, understanding the schedule and output is a constant challenge when using a traditional manual schedule, particularly among manufacturers that produce various products. The multiobjective optimization genetic algorithm (MOGA) is a relatively superior method of solving multiobjective optimization problems; therefore, we used a MOGA to solve flexible job-shop problems for a middle-scale screw manufacturer in Taiwan. For solving the problems of incorrect jobs assign and diversity problem of traditional genetic algorithm (GA) caused by encoding method when applying traditional GA in the flexible manufacturing environment, a refined GA was proposed. Two-phase test has performed for proposed approach, using a classical benchmark of distributed and flexible jobs-shop scheduling problem, and 80 set of work orders, the empirical results indicated that the proposed model yielded substantial savings, regardless of the total order completion time, machine retooling rate, and average machine load rate.

3A1-V02 トレッドミルを用いた脛骨疲労骨折発生リスクの評価(デジタルヒューマン)

Tibial stress fractures are one of the most common and potentially serious overuse injuries in runners. Despite the fact that the tibial stress fractures are related to vertical ground reaction force at early contact phase, a few study has been done for quantification of the variability of the risk parameters. The aim of this study was to quantify the variability of risk parameters for the stress fractures in able-bodied runners. Eight male subjects were asked to run at three different velocities (2.5, 3.0, 3.5 m/s) on a treadmill mounted on the force plates. From the vertical ground reaction force, we calculated coefficient of variation (CV) following lower extremity loading variables; vertical impact peak, vertical instantaneous loading rate and vertical average loading rate. We found that there were no significant differences in the CV of the loading variables in each speed, indicating that variability of loading variables during running is independent from running speeds.

Packed bed up-flow anaerobic sludge blanket combined with multistage sand fine roughing filtration for municipal wastewater treatment and reuse

There is a high potential for reuse of treated wastewater due to the shortage of renewable water resources for agricultural purposes in many countries of the world. To achieve this goal, an integrated anaerobic pilot plant treatment system treating almost 10 m 3 /day of wastewater was designed, manufactured and installed in a nearby wastewater treatment plant. The treatment scheme consists of a packed bed up-fl ow anaerobic sludge blanket (P-UASB) with corrugated lamella sheets, followed by inclined plate settler (IPS). However, to obtain a treated effl uent amenable for reuse, post-treatment was carried out using a multi-stage roughing fi ne fi ltration unit (MSRFF). The pilot plant was operated at average hydraulic fl ow rate of 10 m 3 /day with average organic loading rate of 3.27 kg chemical oxygen demand (COD) m 3 /day. Two retention times in P-UASB namely, 4 and 6 h were investigated. The performance of the treatment scheme was monitored via physico-chemical as well as bacteriological and parasitological analysis. Treatment of wastewater by P-UASB followed by IPS produced a high quality effl uent. Average removal rates of COD, biochemical oxygen demand (BOD) and total suspended solids (TSS) were 75, 70.6 and 91.3, respectively, with average corresponding residual values of 75, 58 and 18 mg/l. However, to obtain sustainable quality of treated effl uent for reuse, post-treatment using MSRFF improved the quality of treated wastewater both chemically and biologically. The average residual concentrations of COD, BOD and TSS were 60, 34 and 10.9 mg/l, respectively, while almost complete removal of Fecal Coliforms was achieved. The treatment scheme proved to be a very promising approach for wastewater treatment for reuse in agricultural purposes.

Innovative sustainable anaerobic treatment for wastewater

The main objective of this study is to demonstrate and implement a cost-effective system for low-strength municipal wastewater treatment in rural areas. An integrated compact anaerobic treatment pilot plant unit was designed, constructed and operated for almost two years. The pilot plant consists of three successive compartments mainly: primary sedimentation (PS), packed bed upflow anaerobic sludge blanket (P-UASB) and inclined plate settler. The pilot plant was operated continuously at a hydraulic loading rate of 6 m3/day, average organic loading rate of 2.03 kg COD/m3/day and average retention time of 4 h at the P-UASB and a total retention time 6 h for the integrated treatment unit. The performance of the treatment train was monitored via physicochemical as well as bacteriological and parasitological analysis. The average removal rates of chemical oxygen demand, biological oxygen demand and total suspended solids were 78, 79 and 91%, respectively, with corresponding average residual values of 71 mgO2/L, 39 mgO2/L and 18 mg/L. Bacterial analysis indicated that great majorities were removed but still some residuals exist. The treated wastewater, after disinfection, was complying with the Egyptian Code for wastewater reuse in restricted irrigation. The results indicated that the total life cost of the pilot plant, during the research period, proved to be a cost-effective process for treating low-strength wastewater.