TMPA 卫星降水数据的评估与校正

卫星遥感降水由于时空分辨率的优势在现代水文模拟中正起着越来越大的作用。本研究对黄河源区的两套卫星降水产品(TMPA准实时3B42RT和研究数据3B42V6)进行了详细评估,结果表明,3B42RT与3B42V6相比会明显高估地面降水,而两者对降水事件的反演能力基本一致。通过引入"降水重心"的概念,两套卫星降水产品均可以基本反映降水的空间分布及长期演变过程。在两者尤其是3B42RT数据的校正中,首先将卫星数据与地面站点月降水对比,再等比例降尺度回日降水,然后尝试逐步订正和最优插值两种残差处理方法,从而使降水量和降水分布的精度进一步提高。最后用校正后的卫星降水驱动分布式水文模型,利用输出径流间接验证校正的效果。     

Improving microbiological food Safety in peri-urban Mali; an experimental study

IntroductionTwenty years ago, a WHO review of the literature assumed that most food-borne disease transmission in developing countries takes place within the home, and advocated a major programme of interdisciplinary research to develop and test cost-effective interventions to promote food hygiene.MethodsThe HACCP approach was applied step by step, to two selected weaning foods prepared by 15 volunteer mothers in peri-urban Mali. After setting Critical Control Points (CCP), actions were taken to control, reduce or eliminate microbial growth at these points. 432 food samples were collected and examined for thermotolerant coliforms in a local laboratory to assess the effectiveness of the approach. Lessons learnt were translated into messages delivered in a pilot study.ResultsTraditional cooking was very effective in eliminating faecal contamination; reheating was as effective as cooking when adopted, because there was no significant difference in the temperatures reached in both cases. Behavioural corrective actions were effective in controlling faecal contamination at the other CCPs (serving the child after cooking and after reheating).ConclusionIn conclusion, the HACCP experiment improved significantly the bacterial safety of both types of weaning food studied.     

Assessment and Improvement of IDF Generation Algorithms Used in the IDF_CC Tool

Water Resources Management - Climate change will modify the spatio-temporal variation of hydrological variables worldwide, potentially leading to more extreme events and hydraulic infrastructure...     

Black Hole Attack Prevention in Wireless Peer-to-Peer Networks: A New Strategy

Mobile peer-to-peer networking (MP2P) is a relatively new paradigm compared to other wireless network technologies. In the last 10–15 years, it has gained tremendous popularity because of its usefulness in applications such as file sharing over the Internet in a decentralized manner. Security of mobile P2P networks represents an open research topic and a main challenge regarding the vulnerability of these networks and their convenience to different security attacks such as black hole, Sybil, etc. In this work, we analyze the black hole attack in wireless P2P networks using the AODV as the routing protocol. In a black hole attack, a malicious node assumes the identity of a legitimate node, by creating forged answers with a higher sequence number, and thus forces the victim node to prioritize it as a relay node. We propose a solution based on a modification of the AODV routing protocol, taking into account the behavior of each node participating in the network. The performances of our proposal are evaluated by simulation.

     

Capital and operating costs of full-scale fecal sludge management and wastewater treatment systems in Dakar, Senegal

A financial comparison of a parallel sewer based (SB) system with activated sludge, and a fecal sludge management (FSM) system with onsite septic tanks, collection and transport (C&T) trucks, and drying beds was conducted. The annualized capital for the SB ($42.66 capita(-1) year(-1)) was ten times higher than the FSM ($4.05 capita(-1) year(-1)), the annual operating cost for the SB ($11.98 capita(-1) year(-1)) was 1.5 times higher than the FSM ($7.58 capita(-1) year(-1)), and the combined capital and operating for the SB ($54.64 capita(-1) year(-1)) was five times higher than FSM ($11.63 capita(-1) year(-1)). In Dakar, costs for SB are almost entirely borne by the sanitation utility, with only 6% of the annualized cost borne by users of the system. In addition to costing less overall, FSM operates with a different business model, with costs spread among households, private companies, and the utility. Hence, SB was 40 times more expensive to implement for the utility than FSM. However, the majority of FSM costs are borne at the household level and are inequitable. The results of the study illustrate that in low-income countries, vast improvements in sanitation can be affordable when employing FSM, whereas SB systems are prohibitively expensive.     

Interference‐aware clustering approach improving QoS for linear WSNs using a token‐based MAC protocol

Wireless sensor networks (WSNs) have received a lot of attention from both academia and industry due to the increasing need for ubiquitous computing for monitoring applications, the continuous advances in miniaturization of electronic devices, and the ultra‐low‐power wireless technologies. These innovations in technology have driven the curiosity to use sensor networks in a new kind of applications such as road track or railway monitoring, border monitoring, oil and gas, or even water pipeline monitoring. Due to the underlying linear topology of these applications, a new type of network, called a linear sensor network (LSN), has emerged. Because of the specific characteristics of this application and the resource constraints of sensors, some of the major challenges faced in LSNs are to reduce end‐to‐end delays, to maximize the packet delivery ratio to a sink, and an even distribution of the load between nodes. To achieve these objectives, it is necessary to control node‐to‐node packet traffic conditions and to manage radio interference created by simultaneously active nodes. This paper addresses these challenges and proposes a new method of clustering LSNs that reduces or controls radio interference risks in order to satisfy these objectives, application needs, and the resource limitations of sensor nodes in the best possible way. This method is applied for LSNs using a token‐passing mechanism to access the medium. The performance evaluation is conducted by using a realistic propagation model in the analytical evaluation and also a NS‐2 simulation process.     

Energetic and exergetic analysis of a triple-effect distiller driven by solar energy

This paper relates to the energetic and exergetic analysis of single-, double- and triple-effect distiller driven by solar energy. Energetic analysis makes it possible to define an applicable zone of operation according to the following criteria: water rejection limit to 50%, maximum salinity limit to 5.5%, and minimum energy consumption. This analysis also makes it possible to quantify energies: energy necessary for the vapour condensation and the power consumption per unit mass of pure water. Exergetic analysis makes it possible to show that the most significant exergy losses are condenser losses and water alimentation losses and that the condenser losses decrease with the number of effects. The exergetic efficiencies have also been found. They are located between 19 and 26% for a triple-effect system, between 17 and 20% for a double-effect system, and less than 4% for the single-effect system. Consequently, it seems interesting to implement a double- or triple-effect system.     

Application of commercial biochemical oxygen demand inocula for biodegradable dissolved organic carbon determination

Biochemical oxygen demand (BOD) and biodegradable dissolved organic carbon (BDOC) measure the amount of biodegradable organics in water samples using mixed culture seeds. The BOD method relies on the dissolved oxygen reduction while the BDOC procedure, which is more novel, is based on the dissolved organic carbon decrease during the incubation. In this study, three commercial BOD seeds, namely BOD Seed, Bi-Chem and Polyseed, were tested as inocula for BDOC measurement. Standard solutions, secondary effluent and raw surface water samples were used. BDOC exertions provided by the commercial seeds were compared with those obtained from two existing BDOC inocula, indigenous and mixed liquor suspended solid (MLSS) seeds. The commercial and indigenous inocula provided similar exertion trends and BDOC results that were not significantly different for surface water samples while the results for secondary effluent samples were inconclusive. The MLSS inoculum tend to provide slightly higher BDOC values and faster exertion kinetics than the commercial and indigenous inocula. The exertions by all five inocula could be expressed well with first-order kinetics for all cases that enough data were available for kinetics evaluation. The commercial seeds were similar in terms of BDOC determination accuracy and precision, and exertion kinetics. It is possible to use the commercial BOD inocula as seeds for BDOC determination but the results might not be statistically the same as those of the indigenous inoculum for certain types of samples.     

Eco Insulation Materials： Reduction of Cooling Loads of a House Made of Breeze Block or Laterite in a Dry Tropical Climate

In this paper, we study the influence ofeco materials for roof insulation and fiber-reinforced mortar coatings on cooling loads of a home in dry tropical climate. The walls of the house are made of cinderblock or laterite and the insulating material of a roof panel is made with lime （24%）, cement （6%）, water （50%） of vegetable fibers hibiscus sabdariffa （16%）, tree widespread in Burkina Faso and sugar cane bagasse （4%）. This panel roof insulation and the fiber-reinforced mortar were characterized at the Laboratory of Physics and Chemistry of the environment by the hot plate method. The building is modeled in TRNSYS using climate data from the city of Ouagadougou. The results obtained show that in the warmer months of the year, that is to say in March and April, the relative differences between heat gains the configurations ＂breeze block-coating mortar and roof not insulated＂ and ＂laterite- fiber-reinforced mortar coating and insulated roof＇ vary between 15.6% and 16.8%. The configuration ＂laterite-fiber-reinforced mortar coating and insulated roof allows a reduction of annual heat gains of 15.5% compared to the configuration ＂breeze block-coating mortar and roof not insulated＂.