Grass Surface Research Articles

An Experimental Study on Observed Heating Characteristics of Urban Pavement

Urban climate is modified resulting in its temperature warmer and drier than surrounding sub urban and rural area. One of the major causes of the modification is built environment which is the process of urbanization where vegetated surfaces are converted to asphalt and concrete surfaces. Temperature distribution in urban canopy layer is highly affected by the urban \radiation balance. Solar radiation incident on the urban surfaces is absorbed and then transformed to sensible heat. Most of the solar radiation impinges on roofs, and the vertical walls of the buildings, and the ground level. Outdoor experiments were conducted to investigate the effects of different movement of materials on the urban thermal environment. Meteorological conditions such as air temperature, pavement surface temperature, relative humidity and wind velocity were recorded to determine the heating characteristics and temperature differences among asphalt, concrete, interlocking bricks and grass surfaces. Additionally, surface albedo was also measured in order to calculate the rate of reflectivity of the four porous and non- porous pavements. This paper confirms that the net balance between the solar gains and the heat loss by the emitted long wave radiation determines the thermal balance of urban areas. Because the radiant heat loss is slower in urban areas and the net balance is more positive than in the surrounding rural areas and thus higher temperatures are present. Keywords: Porous, Non Porous Pavement, Urban environment, thermal characteristics, Albedo, solar radiation

Comparison of plantar loads during treadmill and overground running

ObjectivesThe objective of this study is to compare plantar loads during treadmill running and running on concrete and grass surfaces. DesignCrossover study design was used in the study. MethodsA total of 16 experienced heel-to-toe runners participated in the study. Plantar loads data were collected using a Novel Pedar insole sensor system during running on the treadmill, concrete, and grass surfaces at 3.8m/s running speed and then analyzed. ResultsCompared with running on the two other surfaces, treadmill running showed a lower magnitude of maximum plantar pressure and maximum plantar force for the total foot, maximum plantar pressure at two toe regions, and maximum plantar force for the medial forefoot region and two toe regions (p<0.0017). Treadmill running also showed a longer absolute contact time at two toe regions compared with running on the other two surfaces (p<0.0017). ConclusionsTreadmill running is associated with a lower magnitude of maximum plantar pressure and a lower maximum plantar force at the plantar areas. These results suggest that the plantar load distribution in treadmill running is not the same as the plantar load distribution in running on overground surfaces. Treadmill running may be useful in early rehabilitation programs. Patients with injuries in their lower extremities may benefit from the reduction in plantar loads. However, the translation to overground running needs investigation.

Footwear traction at different areas on artificial and natural grass fields

Footwear traction has been linked to lower-extremity injuries with the theory that higher traction leads to an increased incidence of injury. Recent studies have challenged this showing similar injury rates on artificial turf, which has higher traction than natural grass. This could suggest that the magnitude of traction may not be as relevant for injury as relative changes from one location to another, due to inconsistencies in the surface. The purpose of this study was to compare the traction at various locations on an in-fill artificial turf and natural grass surface. A portable traction tester measured the traction of three shoes at six locations on both surfaces. The results indicate that over the course of a season the traction on natural grass changes considerably, especially rotational traction. Surprisingly the artificial turf surface also had areas of high and low traction due to the movement of the in-fill material during play.

Incidence and Risk Factors for Injuries to the Anterior Cruciate Ligament in National Collegiate Athletic Association Football

Background: Injuries to the anterior cruciate ligament (ACL) are common in athletic populations, particularly in athletes participating in football, soccer, and skiing. Purpose: The purpose of this study was to analyze the National Collegiate Athletic Association (NCAA) Injury Surveillance System (ISS) men’s football ACL injury database from the playing seasons of 2004-2005 through 2008-2009 to determine the incidence and epidemiology of complete injury to the ACL in NCAA football athletes. Study Design: Descriptive epidemiology study. Methods: The NCAA ISS men’s football database was reviewed from the 2004-2005 through 2008-2009 seasons using the specific injury code, “Anterior cruciate ligament (ACL) complete tear.” The injury rate was computed for competition and practice exposures. Ninety-five percent confidence intervals (CIs) for the incident rates were calculated using assumptions of a Poisson distribution. Pairwise, 2-sample tests of equality of proportions with a continuity correction were used to estimate the associations of risk factors such as event type, playing surface, season segment, and football subdivision. Descriptive data were also described. Results: The ACL injury rate during games (8.06 per 10,000 athlete-exposures [AEs] 95% CI, 6.80-9.42) was significantly greater than the rate during practice (0.8 per 10,000 AEs 95% CI, 0.68-0.93). Players were 10.09 (95% CI, 8.08-12.59) times more likely to sustain an ACL injury in competition when compared with practices. When practice exposures were analyzed separately, the injury rate was significantly greater during scrimmages (3.99 per 10,000 AEs 95% CI, 2.29-5.94) compared with regular practices (0.83 per 10,000 AEs 95% CI, 0.69-0.97) and walk-throughs (0 per 10,000 AEs 95% CI, 0-0.14). There was an incidence rate of 1.73 ACL injuries per 10,000 AEs (95% CI, 1.47-2.0) on artificial playing surfaces compared with a rate of 1.24 per 10,000 AEs (95% CI, 1.05-1.45) on natural grass. The rate of ACL injury on artificial surfaces is 1.39 (95% CI, 1.11-1.73) times higher than the injury rate on grass surfaces. Conclusion: Between 2004 and 2009, NCAA football players experienced a greater number of ACL injuries in games compared with practices, in scrimmages compared with regular practices, and when playing on artificial turf surfaces. This latter finding will need to be confirmed by additional studies.

Assessment of thermal anisotropy on remote estimation of urban thermal inertia

Thermal inertia over vast earth surfaces is a crucial parameter in many related disciplines. However, remote estimates of urban thermal inertia show anisotropy effects due to thermal anisotropy. This study investigates the impacts of thermal anisotropy on the estimation of urban thermal inertia. We present the concepts of DTI (directional thermal inertia) and DATI (directional apparent thermal inertia) to describe this anisotropic effect. A combined approach to estimating thermal inertia named NLS (nonlinear least square) is proposed as a compromise solution using temporal temperature measurements. Intercomparisons between methods are indirectly conducted by predicting surface temperatures, and the results indicate the NLS has higher accuracy of 1 to 2K. The DTI estimation over an urban scale model, together with flat concrete and grass surfaces, reveals that the DTI intensity is significant when DRTs (directional radiometric temperatures) are used as inputs. Over the scale model, the DTI and DATI values range from 0.028 to 0.038K−1 and from 1530 to 2970W∙s1/2∙m−2∙K−1 if the zenith and azimuth are between −60° and +60° and between 0° and +360°, respectively. Further discussions demonstrate that DRT intensity has an approximate linear relationship with DTI intensity and that it thus could be used as a predictor of DTI intensity. We finally propose that using complete urban surface temperatures instead of the DRT would be better to estimate urban thermal inertia from the perspective of surface energy balance.

Comparison of Plantar Loads During Running on Different Overground Surfaces

The objective of this study is to compare plantar loads during running on different overground surfaces. Fifteen heel-to-toe runners participated in the study. Plantar load data were collected and analyzed using an insole sensor system during running on concrete, synthetic rubber, and grass surfaces at a running speed of 3.8 m/s. Compared with running on concrete surface, running on natural grass showed a lower magnitude of maximum plantar pressure at the total foot (451.8kPa vs. 401.7kPa, p = 0.016), lateral midfoot (175.3kPa vs. 148.0kPa, p = 0.004), central forefoot (366.3kPa vs. 336.8kPa, p = 0.003), and lateral forefoot (290.2kPa vs. 257.9kPa, p = 0.004). Moreover, running on natural grass showed a longer relative contact time compared with running on a concrete surface at the central forefoot (81.9% vs. 78.8%, p = 0.017) and lateral forefoot (75.2% vs. 73.1%, p = 0.007). No significant difference was observed in other multiple comparisons. Different surfaces affected the plantar loads while running. The differences may help us to understand potential injury mechanisms.

Modeling the radiation balance of different urban underlying surfaces

An urban net all-wave radiation parameterization scheme is evaluated using annual datasets for 2010 recorded at a Beijing urban observation site. The statistical relationship between observed data and simulation data of net radiation has a correlation coefficient of 0.98 and model efficiency of 0.93. Therefore, it can be used to simulate the radiation balance of Beijing. This study analyzes the variation in the radiation balance for different underlying surfaces. To simulate radiation balance differences, we set four pure land-cover types (forest, grass, roads, and buildings). Keeping all other conditions inputted unchanged, we model the radiation balance by changing the land-cover type. The results show that the effects of different underlying surfaces on radiation differ, and that there is much upward long-wave radiation, accounting for 84.3% of the total radiation energy falling incident on the land surface. The annual averages of net radiation for the four land-cover types are in the range of 38.2–53.4 W/m2. The net radiation of the grass surface is minimal while that of the roads surface is maximal. Additionally, with urbanization the net radiation values of common types of land-cover change, such as conversion from forest to roads, grass to roads, and grass to buildings, all have increasing trends, indicating that net radiation usually increases with urban sprawl.

National Assessment of Pesticide Runoff Loads from Grass Surfaces

Pesticide runoff loads from grass surfaces were estimated through simulation experiments for 37 chemicals registered for use on U.S. lawns and golf courses. Simulation runs were made for each chemical and surface (lawns, greens, fairways) using 100-year weather records generated for nine U.S. cities. Results were summarized as mean annual and 1-in-10 year annual maximum daily pesticide loads. These loads varied greatly with pesticide, grass surface, and city, ranging from less than one to over 400 g/ha for mean annual loads and from less than one to over 500 g/ha for 1-in-10 year maximum daily loads. Mean annual loads averaged over the 37 chemicals and three grass surfaces were found to be closely related to growing season precipitation. Variations among the nine cities were well-captured by three general climate categories: humid, represented by Atlanta and Houston; mesic, as with Albany, Columbus, Madison, and Olympia; and dry, represented by Bismarck, Fresno, and Roswell. Mean annual pesticide runoff...

Injury risk associated with physical demands and school environment characteristics among a cohort of custodial workers

Few epidemiological studies have investigated the relationship between work exposures and injury risk among custodians. The relationship between injury risk and occupational physical demands (e.g. pushing/pulling, lifting) and school environment characteristics (e.g. school type, season) was investigated among a cohort of 581 school custodians over a 4-year period. In the final Poisson regression models, the risk of injury was associated with time spent in pushing/pulling tasks in a dose–response manner increasing to a five-fold risk among the highest quartile of exposure (risk ratio = 5.15, 95% CI 1.00, 26.5). Injury risk was also associated with working during the school year compared to the summer, working in a school with grass vs. gravel grounds and working in a school with detached classrooms. Results help to target interventions such as alternative methods for floor cleaning to reduce the pushing/pulling demands of custodial work and to support decisions for alternatives to detached classrooms and grass surfaces. Statement of Relevance: This study examines ergonomic factors (physical demand exposures, school environment characteristics) associated with injury risk among custodial school workers. The findings help schools to target interventions to reduce the physical demands associated with injuries and to design school environments to reduce exposures.

A study on the cooling effects of greening in a high-density city: An experience from Hong Kong

Greening is a useful mitigation strategy for planners mainly from a visual perspective. For high-density urban living environment such as Hong Kong, urban greening helps cooling the air and providing shade; it also helps lowering building energy consumption by providing a better outdoor boundary condition. Many researchers have also suggested that greening may be employed as a strategy for combating the ill effects of urban Heat Island (UHI). Working towards a set of better greening guidelines for urban planners, the current paper first provides a comprehensive review of planning with urban greening. It then describes parametric studies that have been conducted to investigate the preferred location, amount, and types of vegetation for urban planning. The parametric studies employed the numerical model ENVI-met, verified using field measurements, to simulate 33 cases with different combinations of factors. For benefiting urban activities, ambient air temperatures at the pedestrian level are compared among different greening strategies and building heights. For a city such as Hong Kong, which has a high building-height-to-street-width ( H/ W) ratio, the present study reveals that roof greening is ineffective for human thermal comfort near the ground. Trees are also suggested to be more effective than grass surfaces in cooling pedestrian areas. The amount of tree planting needed to lower pedestrians level air temperature by around 1 °C is approximately 33% of the urban area. The present study allows urban planners to identify more precisely the greening principles, amount and policies necessary for better urban living environment in high-density cities.

Intravascular haemolysis during prolonged running on asphalt and natural grass in long and middle distance runners

Surface features such as uneven playing surfaces, low impact absorption capacity and inappropriate friction/traction characteristics are connected with injury prevalence whereas force impact during foot strike has been suggested to be an important mechanism of intravascular haemolysis during running. We aimed to evaluate intravascular haemolysis during running and compare the effect of running on two different types of surfaces on haemolysis. We selected two surfaces (asphalt and grass) on which these athletes usually run. Participants were randomly assigned to group A (asphalt) or group B (grass) with 10 athletes in each group. Each athlete completed one hour of running at the calculated target heart rate (60–70%). Venous blood samples were collected before and immediately after running. We measured unconjugated bilirubin (UBR) (mg · dl−1), lactate dehydrogenase (LDH) (μ · ml−1), haemoglobin (g · l−1) and serum ferritin (ng · ml−1) as indicators of haemolysis. Athletes who ran on grass demonstrated an increase in the haematological parameters (UBR: P < 0.01, LDH: P < 0.05) when compared to athletes who ran on asphalt (UBR: P < 0.05, LDH: P = 0.241). Our findings indicate that intravascular haemolysis occurs significantly after prolonged running. Furthermore, we conclude that uneven grass surface results in greater haemolysis compared to asphalt road.

The effect of lateral heel studs on the kinematics of the equine digit while cantering on grass

This study aimed to assess the effect of lateral heel studs on foot-ground interaction in the horse by quantifying foot slip during stance whilst cantering on a grass surface. It was hypothesised that using studs would decrease foot slip distance on the ground conditions tested. Nine horses were ridden with and without a stud placed laterally in the shoe of each of the 4 feet. High speed video-analysis was used to track hoof markers and to provide data quantifying foot slip distance, slip duration and stance duration. Using studs resulted in a significant decrease in foot slip distance in all four limbs (all P values<0.004). The magnitude of the difference in slip distance with and without studs was greatest in the trailing limbs. The results supported the hypothesis that using studs will decrease foot slip distance in horses cantering on a grass surface, and additionally, highlights that stud efficacy may vary between limbs. The decrease in slip distance with studs demonstrated increased traction and a more stable foot-ground interaction, although this may cause a concomitant increase in the required energy dissipation, either within the limb or via surface deformation. The effect of repetitive usage of studs in the aetiology of musculoskeletal conditions should therefore be investigated further.

Effect of vegetation biomass structure on thermal performance of tropical green roof

The passive cooling effect of green roofs in humid, tropical Hong Kong was investigated with reference to three vegetated plots, grass, groundcover herb, and shrub, with contrasting growth form and biomass structure and a bare control plot. Temperature was monitored at 15-min intervals for a year at seven levels: high (H) at 200 cm, middle (M) at 60 cm, low (L) at 20 cm, surface, soil, rockwool (water storage), and roof-tile surface. The findings indicated the crucial roles played by biomass quantity and structural complexity in passive cooling functions. Temperature variations of vegetated roofs occurred mainly during the day, with lower maximum and minimum than the control, but they did not cool air at night better than the control. Control and grass surfaces were warmed above the ambient temperature, but groundcover and shrub surfaces followed the ambient. Despite complex biomass structure, shrub created the most extreme diurnal air temperature regime. Despite simple biomass structure, grass cooled air more effectively than groundcover and shrub. Four anomalies in the vertical temperature profile were detected. First, the grass roof cooled daytime near-ground air to create a suspended temperature inversion. Second, the stagnant air within the shrub biomass trapped heat to generate a daytime canopy temperature inversion. Third, the elevated branch-foliage biomass of groundcover and shrub brought passive cooling to form a perched thermal discontinuity. Fourth, the air gap of the plastic drainage layer arrested downward heat transmission in all vegetated plots to form a subsurface thermal discontinuity. The findings provide hints on species choice and design of green roofs.

A capillary pumping device utilizing super-hydrophobic silicon grass

In this study, we show that a compact silicon grass surface can be generated by utilizing the induced coupled plasma method with suitably chosen fabrication parameters. This super-hydrophobic structure suspends deionized water on top of the grass and keeps the contact angle at around 153°. The silicon grass is used to improve the driving efficiency of a capillary pumping micro-duct (without sidewalls), which is completely defined by a bottom hydrophilic stripe (adjacent to a Teflon substrate) and a fully top-covered hydrophobic Teflon surface which is coated on a glass substrate. The channel has a height of 3 µm and a width of 100 µm. In this work, the Teflon substrate is replaced with the silicon grass surface. When the fluid is flowing through the micro-duct on the stripe, the interface between the silicon grass and the hydrophilic stripe forms a stable air cushion barrier to the fluid, thus effectively reducing the frictional force. By changing only the interface with this replacement, we demonstrate that the average measured velocities of the new design show improvements of 21% and 17% in the driving efficiency over the original design for transporting deionized water and human blood, respectively. It is also shown that the measured data of the present design are closer to the values predicted by a theoretical analysis which relates the flow velocity to the contact angles, surface tension and fluid viscosity.

The Cost of Running on Natural Grass and Artificial Turf Surfaces

The purpose of this study was to evaluate the metabolic cost of running (Cr) on natural grass (NG) and artificial turf (AT), compared with a hard surface (HS), that is, asphalted track. Eight amateur soccer players (mean ± SD: age 22.9 ± 2.3 years, body mass 69.0 ± 4.7 kg, and height 178 ± 5 cm) completed 9 runs (3 surfaces × 3 speeds, i.e., 2.22, 2.78, 3.33 m·s) of 6 minutes, in a random order on the different surfaces. Characteristics of the running surfaces were assessed at 3 points of each running track by measuring shock absorption and standard vertical deformation, via an 'artificial athlete' device according to FIFA protocol. No significant interactions (2-way ANOVA analysis; p = 0.38) were found between running surfaces and running speeds. A significant main effect for surface was found. The average Cr values were 4.02 ± 0.25 J·kg·L·m on HS, 4.22 ± 0.35 J·kg·L·m on NG, and 4.21 ± 0.31 J·kg·L·m on AT. The Cr was also higher at 3.33 m·s compared with the Cr measured at the other 2 running speeds. In conclusion, we found a Cr of ∼ 4.20 J·kg·L·m on both natural and artificial grass football pitches, in accordance with similar percentage shock absorption characteristics of these 2 tested surfaces. Our finding allows a better computation of the Cr on NG and AT, and supports the exclusion of the Cr as a potential factor for the higher physical effort in matches played on artificial turf, as reported by soccer players.

A Study on the Thermal Performance of the Living Wall System

PP-29-190 Background/Aims: This study aimed at framing alternative urban planning scenarios reflecting urban planning factors, performing urban climate simulation, and evaluating low energy characteristics from the viewpoint of urban temperature and energy savings. Methods: Monitoring thermometer of artificial ground greening to confirm its mitigation effect of plant evapotranspiration was carried out. Results: According to result of monitoring that, in case of green roof, surface of Grass was lower 2.37°C than surface of concrete and surface of Sedum was lower 3.57°C than surface of concrete in September. In case of green wall, surface of grass was lower 4.78°C than surface of concrete wall, surface of ivy was lower 2.55°C than surface of concrete wall in September. Therefore, it was found that green roof and green wall could have effect on mitigation of microclimate. Conclusion: The best results were recorded from the grass and Sedum surface presenting highest mitigation effect and lowest daily temperature deviation. From this monitoring, it was confirmed that artificial ground green can do its role of temperature mitigation as green does. Environmental Exposure and Health

Performance of passive and reactive profiled median barriers in traffic noise reduction

Median noise barriers, like parallel noise barriers, can be employed to reduce the impact of traffic on roadside communities via the direct propagation path. The performance of different shapes of median barriers was compared using reactive and passive surfaces and a 2D boundary element method (BEM). In the case of reactive surfaces, quadratic residue diffusers (QRDs) and primitive root diffusers (PRDs) were used on the top and stem surfaces of median barriers. To introduce passive barriers, two different absorbent materials including fibrous material and a grass surface with flow resistivity of 20 000 and 2500 kg/(s·m2), respectively, were similarly applied. The effect of thin absorptive barriers was similar at lower frequencies and better at mid and high frequencies to that of their equivalent rigid barriers. More improvement was achieved by covering the top surface of thick barriers with grass rather than with fibrous material. The performance of QRD and PRD barriers where the diffuser was located on the top surface was more frequency dependent than that of barriers coated with fibrous material. A comparison of the average A-weighted insertion loss in the thick barriers showed that the greatest improvement (2.59 dB (A)) was achieved using a barrier of 30-cm thickness covered with grass.

Aeolian archaeology

Landscapes characterised by a substantial presence of aeolian (wind-blown) sand are predominantly coastal, and range from active dunefields with high and unstable relief, to smoother and more stable grassed surfaces which may be subject to some degree of agricultural use. Some are remote and inaccessible, but others exist in closer proximity to conurbations and tourist areas, and the impact of visitors is therefore comparatively great. In addition to the ever-present scouring and redistributing forces of sea and wind, other pressures on the stability of these landscapes include aggregates quarrying, development and the ubiquitous presence of wild burrowing fauna, most obviously the rabbit. Sand creates dynamic 'soft' landforms which are subject to continuing change, to the extent that photographs or maps of just 100 years ago often present very different topographies from those visible today. This report is a collection of five papers presented on the archaeology of Scotland's coast line.

Aeolian archaeology: the archaeology of sand landscapes in Scotland

Landscapes characterised by a substantial presence of aeolian (wind-blown) sand are predominantly coastal, and range from active dunefields with high and unstable relief, to smoother and more stable grassed surfaces which may be subject to some degree of agricultural use. Some are remote and inaccessible, but others exist in closer proximity to conurbations and tourist areas, and the impact of visitors is therefore comparatively great. In addition to the ever-present scouring and redistributing forces of sea and wind, other pressures on the stability of these landscapes include aggregates quarrying, development and the ubiquitous presence of wild burrowing fauna, most obviously the rabbit. Sand creates dynamic 'soft' landforms which are subject to continuing change, to the extent that photographs or maps of just 100 years ago often present very different topographies from those visible today. The encroachment of the sea and continual process of wind-induced change can transform a sand landscape almost overnight. In depositional strata, long periods of stasis may be represented by comparatively shallow soil horizons, which are frequently separated by much deeper bands of sand which may result from wind-blow episodes of far shorter timescale. Dune systems frequently occupy zones of extensive past settlement attraction with numerous environmental advantages, and therefore occur in areas of generally high archaeological potential. Yet their complexity and extreme vulnerability present us with serious problems in terms of balancing an understanding of the archaeology with conservation strategies.

Regional characteristics of dry deposition of sulfur and nitrogen compounds at EANET sites in Japan from 2003 to 2008

Abstract The regional characteristics of estimated dry deposition and total atmospheric deposition, including dry and wet deposition, at 10 EANET sites in Japan from April 2003 to March 2008 are discussed. The components examined for dry deposition were sulfur compounds (SO2 and particulate SO42−) and nitrogen compounds (HNO3, NH3, particulate NO3−, and NH4+). Dry deposition was calculated by the product of the deposition velocity estimated by the inferential method for forest and grass surfaces and the air concentration of each compound. The 5-year mean annual dry deposition amounts for sulfur and nitrogen compounds were in the range of 5–37 and 7–50 mmol m−2 year−1, respectively. The regional characteristics of dry deposition amounts were similar between sulfur and nitrogen compounds, which showed higher deposition in the Sea of Japan side and in the Western Japan. The 5-year mean annual total deposition amounts for sulfur and nitrogen compounds were in the range of 28–77 and 22–130 mmol m−2 year−1, respectively. The contribution of dry deposition to the total deposition amounts was 10–55% and 13–56% for sulfur and nitrogen compounds, respectively. The regional characteristic of total deposition was different between sulfur and nitrogen compounds. Total deposition amounts in Japan were larger than those in CASTNET and EMEP because of high wet deposition, which implied that the increasing emissions of air pollutants in East Asia caused high atmospheric depositions.