Miller, Laura; Santhanakrishnan, Arvind
Flexible plants, fungi, and sessile animals are thought to reconfigure in the wind and water to reduce the drag forces that act upon them. In strong winds, for example, leaves roll up into cone shapes that reduce flutter and drag when compared to paper cut-outs with similar shapes and flexibility. During flash floods, herbaceous broad leaves aquaplane on the surface of the water which reduces drag. Simple mathematical models of a flexible beam immersed in a two-dimensional flow will also reconfigure in flow. What is less understood is how the mechanical properties of a two-dimensional leaf in a three-dimensional flow will passively allow roll up and aquaplaning. In this study, we film leaf roll-up and aquaplaning in tree and vine leaves in both strong winds and water flows.
Bauer, Ulrike; Scharmann, Mathias; Skepper, Jeremy; Federle, Walter
Trichomes are a common feature of plants and perform important and diverse functions. Here, we show that the inward-pointing hairs on the inner wall of insect-trapping Heliamphora nutans pitchers are highly wettable, causing water droplets to spread rapidly across the surface. Wetting strongly enhanced the slipperiness and increased the capture rate for ants from 29 to 88 per cent. Force measurements and tarsal ablation experiments revealed that wetting affected the insects' adhesive pads but not the claws, similar to the 'aquaplaning' mechanism of (unrelated) Asian Nepenthes pitcher plants. The inward-pointing trichomes provided much higher traction when insects were pulled outwards. The wetness-dependent capture mechanisms of H. nutans and Nepenthes pitchers present a striking case of functional convergence, whereas the use of wettable trichomes constitutes a previously unknown mechanism to make plant surfaces slippery. PMID:23256197
Niskanen, Arto J.; Tuononen, Ari J.
The tyre-road contact area was studied visually by means of a high-speed camera and three accelerometers fixed to the inner liner of the tyre carcass. Both methods show a distorted contact area in wet conditions, but interesting differences appeared. First, the contact area in full aquaplaning seems strongly distorted on a glass plate when subjected to visual inspection, while the accelerometers indicate a more even hydrodynamic aquaplaning contact length (CL) across the tyre width. Secondly, the acceleration sensors predict the clear shortening of the CL of the tyre before the critical aquaplaning speed. It can be concluded that the visual contact area and shape are heavily dependent on the transparency of the liquid and smoothness of the glass. Meanwhile, the tyre sensors can provide a CL estimate on any road surface imaginable.
Bauer, Ulrike; Federle, Walter
Carnivorous pitcher plants of the genus Nepenthes capture prey with a pitfall trap that relies on a micro-structured, slippery surface. The upper pitcher rim (peristome) is fully wettable and causes insects to slip by aquaplaning on a thin water film. The high wettability of the peristome is probably achieved by a combination of hydrophilic surface chemistry, surface roughness and the presence of hygroscopic nectar. Insect foot attachment could be prevented by the delayed drainage of the thin water film between the adhesive pad and the surface. Drainage should be faster for insects with a hairy adhesive system; however, they slip equally on the wet peristome. Therefore the stability of the water film against dewetting appears to be the key factor for aquaplaning. New experimental techniques may help to clarify the detailed function of the pitcher plant peristome and to explore its potential for biomimetic applications. PMID:20009546
Hernandez Orue, J.M. [Servicio de Aguas Diputacion Foral de Alava, Vitoria (Spain); Nieves de la Vega Sedo, G.
Requirements of wastewater discharges, in order to maintain and improve receiving water qualities, create a demand of means of wastewater management besides implementation of control systems, technical and economical management programs and financing. In this background, Direccion de Medio Ambiente of Diputacion Foral de Alava, through its Water Service, has settled the need of a integral planning for wastewater management in Rioja Alavesa. This job has been commanded to the engineering consulting AQUA/PLAN, S.A. (Author)
M.O. Hamzah; Z. F. M. JAAFAR; Ahmad, F
Porous asphalt pavement was initially developed for the purpose of improving road safety, best candidate material for quiet pavement and to avoid aquaplaning and skidding in wet weather. However, from previous studies, porous asphalt is able to mitigate surface runoff. Porous asphalt parking lots with underlying reservoir course perform as additional temporary water storage matrix that enables reduction of flash flood. This paper elaborates the development of a new porous asphalt aggregate g...
Poulikakos, L D; Sedighi Gilani, M; Derome, D; Jerjen, I; Vontobel, P
Porous asphalt as a road surface layer controls aquaplaning as rain water can drain through its highly porous structure. The process of water drainage through this permeable layer is studied using neutron radiography. Time-resolved water configuration and distribution within the porous structure are reported. It is shown that radiography depicts the process of liquid water transport within the complex geometry of porous asphalt, capturing water films, filled dead end pores and water islands. PMID:23500651
FIKRIARAZ, MOHAMMAD AFIF
Aspal porus merupakan teknologi perkerasan jalan dengan beberapa kelebihan seperti mengurangi aquaplaning dan meredam kebisingan. Aspal porus saat ini sedang terus dikembangkan oleh beberapa negara, tak terkecuali di Indonesia. Kebutuhan aspal minyak dalam negeri terus meningkat namun tidak diimbangi dengan persediaan yang ada, maka bahan lain seperti Aspal Buton Granular (BGA) dapat menjadi alternatif. Penuaan jangka pendek disebabkan oleh pemanasan berlebih saat proses pencampuran, sehingga...
Porous asphalt as a road surface layer controls aquaplaning as rain water can drain through its highly porous structure. The process of water drainage through this permeable layer is studied using neutron radiography. Time-resolved water configuration and distribution within the porous structure are reported. It is shown that radiography depicts the process of liquid water transport within the complex geometry of porous asphalt, capturing water films, filled dead end pores and water islands. - Highlights: ► The water drainage process in porous asphalt was studied using neutron radiography. ► Despite similar mix designs, different processes of water transport were established. ► Water transport within porous asphalt showed filled dead end pores and water islands
Bauer, Ulrike; Clemente, C J; Renner, T; Federle, W
Carnivorous plants of the genus Nepenthes have evolved a striking diversity of pitcher traps that rely on specialized slippery surfaces for prey capture. With a comparative study of trap morphology, we show that Nepenthes pitcher plants have evolved specific adaptations for the use of either one of two distinct trapping mechanisms: slippery wax crystals on the inner pitcher wall and 'insect aquaplaning' on the wet upper rim (peristome). Species without wax crystals had wider peristomes with a longer inward slope. Ancestral state reconstructions identified wax crystal layers and narrow, symmetrical peristomes as ancestral, indicating that wax crystals have been reduced or lost multiple times independently. Our results complement recent reports of nutrient source specializations in Nepenthes and suggest that these specializations may have driven speciation and rapid diversification in this genus. PMID:22023155
Bauer, Ulrike; Di Giusto, Bruno; Skepper, Jeremy; Grafe, T Ulmar; Federle, Walter
Carnivorous pitcher plants capture prey with modified leaves (pitchers), using diverse mechanisms such as 'insect aquaplaning' on the wet pitcher rim, slippery wax crystals on the inner pitcher wall, and viscoelastic retentive fluids. Here we describe a new trapping mechanism for Nepenthes gracilis which has evolved a unique, semi-slippery wax crystal surface on the underside of the pitcher lid and utilises the impact of rain drops to 'flick' insects into the trap. Depending on the experimental conditions (simulated 'rain', wet after 'rain', or dry), insects were captured mainly by the lid, the peristome, or the inner pitcher wall, respectively. The application of an anti-slip coating to the lower lid surface reduced prey capture in the field. Compared to sympatric N. rafflesiana, N. gracilis pitchers secreted more nectar under the lid and less on the peristome, thereby directing prey mainly towards the lid. The direct contribution to prey capture represents a novel function of the pitcher lid. PMID:22719998
Matilainen, Mika; Tuononen, Ari
We determined the tyre contact length on dry and wet roads by measuring the accelerations of the inner liner with a three-axial accelerometer. The influence of the tyre pressure, driving velocity, and tread depth on the contact length was studied in both types of road surface conditions. On dry asphalt the contact length was almost constant, regardless of the driving velocity. On wet asphalt the presence of water could be detected even at low driving velocities (e.g. 20 km/h for a worn tyre) as the contact length began to decrease from that found in the dry asphalt situation. In addition to improving the performance of active safety systems and driver warning systems, the contact length information could be beneficial for classifying and studying the aquaplaning behaviour of tyres.
M. O. HAMZAH
Full Text Available Porous asphalt pavement was initially developed for the purpose of improving road safety, best candidate material for quiet pavement and to avoid aquaplaning and skidding in wet weather. However, from previous studies, porous asphalt is able to mitigate surface runoff. Porous asphalt parking lots with underlying reservoir course perform as additional temporary water storage matrix that enables reduction of flash flood. This paper elaborates the development of a new porous asphalt aggregate grading design for storm water mitigation using the Nominal Maximum Aggregate Size (NMAS 20 mm. The properties of the mixes were quantified and evaluated in terms of air voids, permeability, abrasion loss and indirect tensile strength. It was found that the proposed gradation has the best permeability and Indirect Tensile Strength (ITS values when compacted at 50 blows per face with a standard Marshal compactor. The porous asphalt slab was prepared using a slab compactor to simulate porous parking lot paving at site. The porous asphalt slab was finally placed inside a locally fabricated water flow simulator to simulate a porous asphalt pavement system for parking lots.