Estimating rainfall distributions at high temporal resolutions using a multifractal model

International audienceRainfall data from 18 stations in the vicinity of Tokyo city, measured to a precision of 1 mm, were analysed for multifractal properties. A multifractal model based on the scaling properties of temporal distribution of rainfall intensities was formulated to investigate the intensity distribution relationships in the available scaling regime. Although conventional analysis did not provide encouraging results with these measurements, an alternative approach that could be applied to rainfall data of widely variable quality and duration was used to establish a scaling relationship between daily and hourly rainfall intensities. Using a discrete cascade algorithm based on the log-Lèvy generator, synthetic hourly rainfall series were generated from the multifractal statistics of daily-accumulated rainfall. Several properties of rainfall time series that are relevant to the use of rainfall data in surface hydrological studies were used to determine, statistically, the degree of agreement between the synthetic hourly series and observed hourly rainfall. Keywords: rainfall modelling, cascades, multifractal, downscalin

Valuing Avoided Soil Erosion by Considering Private and Public Net Benefits

The population in New Zealand is expected to increase to over five million by the mid 2020’s from the current level of 4.3 million (Statistics New Zealand, 2009). An increasing demand for primary produce as a result may put pressure on marginal land to be farmed. Understanding the economic value of avoided erosion in New Zealand is therefore an important factor in policy making to optimise the soil related activities in the economy. Establishing a methodology for estimating the economic value of avoided soil erosion is the first step in assessing the problem. This study uses the future forest scenarios developed by Scion to identify potential afforestation areas and thereby compare the current erosion/sedimentation status under current land-use (non woody vegetation) with potential future afforestation. The study aims to quantify the incremental public and private net benefits from the change in scenario. The notion has come under different headings in the literature, such as on-site and off-site erosion effects or sediment and soil erosion effects, all of which recognize the importance of separation of effects to avoid double-counting. The separation into public and private benefits and costs in this case, while avoiding double-counting, will also help identify appropriate policy instruments to avoid soil erosion damage using the private and public net benefit framework (Pannell, 2008).Environmental Economics and Policy, Land Economics/Use,

Investigation of the agricultural resources in Sri Lanka

The author has identified the following significant results. Several in-house capabilities were developed. The facilities to prepare color composites of excellent quality were developed, using bulk B/W 70 mm transparencies or 1:1,000,000 positive transparencies. These color composites were studied through optical devices on light tables. A zoom transfer scope was also added, enabling direct transfer of LANDSAT composite data on to base maps

The effect of an infra-acetabular screw for anatomically shaped three-dimensional plate or standard plate designs in acetabulum fractures: a biomechanical analysis

Background Various plate shapes and implant configurations are used for stabilization of acetabulum fractures via anterior approaches. Little is known about the biomechanical stability of a two-dimensionally shaped “conventional” plate (“J-Plate”—JP) in comparison to three-dimensionally shaped plate configurations (3DP). In addition, the augmentary effect of an infra-acetabular lag-screw (IACS) fixation for anterior column and posterior hemi-transverse acetabulum fractures has not been clarified in comparison of JP and 3DP constructs. This study analyzed the difference between the biomechanical stability of JP compared to 3DP and the role of an IACS in a standardized acetabular fracture model in a single-leg stance loading configuration. Methods In an artificial bone substitute pelvis model (Synbone© Malans, Switzerland), a typical and standardized fracture pattern (anterior column and posterior hemi-transverse) was created with osteotomy jigs. After anatomic reduction the stabilization was performed using JP or 3DP. Eight pelvises per group were axially loaded in a single-leg stance model up to 400 N. After the load cycle, an additional infra-acetabular screw was placed and the measurement repeated. Fragment displacement was recorded by an optical tracking system (Optitrack Prime 13®, Corvallis, USA). Results In the pure placement, 3DP provided significantly superior stability when compared to JP. Augmentation of JP by IACS increased the stability significantly, up to the level of 3DP alone, whereas augmentation of the 3DP did not result in further increase of overall stability. Conclusion The anatomically shaped plate alone provides a superior biomechanical stability in fixation of an anterior column and posterior hemi-transverse fracture model. In a JP fixation the augmentation by IACS provides similar strength as the anatomically shaped 3DP. By use of the anatomically shaped 3DP the need of a clinically risky application of IACS might be avoidable

Blood flow changes in pelvic vessels associated with the application of an abdominal compression belt in healthy postpartum women

Introduction: Postpartum haemorrhage (PPH) accounts for a high proportion of maternal mortality and morbidity throughout the world. A uterine compression belt which has been developed recently represents a very low tech, low cost solution in managing postpartum haemorrhage. Objectives: To evaluate the blood flow changes in pelvic vessels following application of the postpartum haemorrhage compression belt (Laerdal Global Health, Stavanger, Norway). Methods: The sample included healthy postpartum women within 6 hours of vaginal delivery. The study was performed at Teaching Hospital, Ragama, Sri Lanka. PPH compression belt was applied on the lower abdomen in a supine position with a slight lateral tilt. Patient’s pulse, blood pressure and Doppler indices (RI, PI and PFV) of the uterine, internal iliac and femoral arteries were measured using transabdominal Doppler ultrasonography. Lower limb oxygen saturation was also measured. Measurements were obtained by connecting the subjects to a multimonitor throughout the study period of 20 minutes. Median RI, PI and PFV was calculated and comparisons were made between the baseline and after belt application at 10 and 20 minutes. Results: A total of 20 healthy women were included and the mean time from delivery to study inclusion was 2.5 (range 0.5–5.0) hours. There were no adverse outcomes or altered vital signs noted among participants. Overall there were no significant changes in the internal iliac, uterine and femoral artery blood flow after application of the compression belt. Conclusions: There were no significant changes in the internal iliac, uterine and femoral artery blood flow after application of the compression belt. This preliminary study only shows that the application of the PPH compression belt has no apparent adverse changes in the iliac, uterine and femoral artery blood flow in postpartum mothers

Wireless sensor network based system for underground chemical plume tracking, A

A real-time subsurface chemical plume monitoring and tracking system is being developed that uses wireless-sensor networking to automatically extract data from underground chemical sensors. This system is aimed at tracking plumes caused by the release of toxic chemicals and biological agents into the environment as a result of accidental spills and improper disposal. Current practice involves manual collection of samples from monitoring wells followed by laboratory analysis, an expensive process taking days to weeks; such a delay reduces the effectiveness of mitigation techniques as well. Virtual Sensor Networks (VSN), a novel resource efficient approach for sensor networking being developed to track the migrating underground plumes, will be applicable to a broad class of problems. Laboratory based experiments and simulations are in progress to demonstrate the feasibility of the approach for large-scale plume tracking.This research is supported in part by Army Research Office and the National Science Foundation.1st place, ISTeC Student Research Poster Contest (April 7, 2008)

Benchmarking medium voltage feeders using data envelopment analysis: a case study

Feeder performance evaluation is a key component in improving the power system network. Currently there is no proper method to find the performance of Medium Voltage Feeders (MVF) except the number of feeder failures. Performance benchmarking may be used to identify actual performance of feeders. The results of such benchmarking studies allow the organization to compare feeders with themselves and identify poorly performing feeders. This paper focuses on prominent benchmarking techniques used in international regulatory regime and analyses the applicability to MVFs. Data Envelopment Analysis (DEA) method is selected to analyze the MVFs. Correlation analysis and DEA analysis are carried out on different models and then the base model is selected for the analysis. The relative performance of the 32 MVFs of Western Province, Sri Lanka is evaluated using the DEA. Relative efficiency scores are identified for each feeder. Also the feeders are classified according to the sensitivity analysis. The results indicate that the DEA analysis may be conveniently employed to evaluate the performance of the MVFs. The evaluation is carried out once or twice a year with the MV distribution development plan in order to identify the performance of the feeders and to utilize the available limited resources efficiently

Development of PP/Recycled-PET Blended Low Speed Wheels to Reduce the Virgin Plastic Usage in the Industry

The increase of plastic usage in different applications has a huge impact on the environment due waste generation. This study was focused not only to find a way to reduce the virgin plastic usage but also to convert a commodity plastic waste into a commercial engineering product. Post consumed polyethylene terephthalate (PET) water bottles were used as a source of recycled PET (r-PET) and blended with commercial grade polypropylene (PP) to produce the center part of low speed wheels. Thermomechanical properties of PP/r-PET blends were investigated along with the effect of compatibilization. The quality of prepared wheels was examined with dynamic drum test and impact test. The addition of recycled PET into polypropylene enhanced the properties of blends and it also supported to maintain the fatigue life of the wheel