Effect of different substrates on growth, yield and quality of tomato by the use of geothermal water in the South of Tunisia

Purpose: With growing concern about climate change and the need to reduce the use of fossil fuels, there is increasing interest in the use of renewable energy. In this regard, geothermal energy has a great importance in agriculture activity in southern of Tunisia. By using geothermal heating for greenhouses in this part of Tunisia, production of vegetables attains 30000 tons of which 35% are exported. However, this activity faces some problems of soil diseases and salt accumulation. The main objective for the present research is to solve these problems by soilless cultivation using palm trees wastes as substrates after composting. These substrates give the opportunity to valorise these wastes produced with large amounts every crop season.Methods: The experiment was carried out under a green house involving five replicates and five treatments (1) Control: soil, (2) Palm trees compost, (3) Compost of oasis wastes and animal manure, (4) River sand and (5) Coconut fiber witch is an imported substrate. Plots were planted on with tomato. The measurements determinate were growth, yield and quality.Results. Comparison of means showed that yield of fruits had not any significant difference between treatments. Substrates had no influence on the average fruit weight, ranged from 91.17 g to 95.59 g. The marketable yield and the fruit weight of the tomatoes grown in oasis wastes and animal manure compost were slightly higher compared with those grown in other substrates. The results of data length and stem diameter on seven occasions, showed that plant height and diameter had a significant difference between treatments. The tallest plants were produced by tomato cultivated in soil (382.64 cm). The most vigorous plants were grown in coconut fiber (19.02 mm). TSS (°Brix) content of the fruit was found to differ significantly between substrates. Plants grown on soil and sand produced highest TSS values (5 °Brix). The pH and the EC of the tomato fruit juice were not significantly different in tomato cultivation with different substrates

The Role and Performance of Governmental and Nongovernmental Organizations in Family Planning implementation : Jordan as a Case Study

The role of governmental and nongovernmental nonprofit organizations in population issues has become a familiar reality in contemporary Third World countries. A distinct irony lies in the increasing growth of the role of NGOs in implementing public programs that are conventionally assigned to government bureaucracy. In certain circumstances, these organizations become an outlet to deliver and do certain things that government agencies are not able to do. Although there is an extensive body of research and publications on nongovernmental and charitable organizations in the Third World, there are only a few cases where small NGOs are working directly with the government in a sensitive social program such as family planning. The relationship between the two sectors may stem from the complementarity of their strengths and weaknesses. This study explored the role and performance of governmental and nongovernmental nonprofit organizations in family planning implementation in Amman, Jordan. Based on both qualitative and quantitative research methods, the study attempted to establish a comparison between two family planning programs, one implemented by the Ministry of Health and the other by the Jordan Association for Family Planning and Protection. The study highlighted the advantages and disadvantages that each organization faces and how their characteristics influence their performance. Twelve clinics/centers were selected as a sample for this study. Five clinics represented the Jordan Association for Family Planning and Protection, and seven centers represented the Ministry of Health. The sample was unevenly distributed between the two organizations due to their respective sizes. The analysis was based on the data gathered from different sources and multiple research methods. Structured and semi-structured interviews with open-ended questions and situational analysis were conducted with various respondents (N = 60), including high administrators, medical and paramedical staff, policy makers, and clients. Also, field observations were conducted in the selected clinics and centers. The research shows that nongovernmental nonprofit organizations have played the leading role in family planning implementation in Jordan, despite their limited resources. The analysis also suggests that tangled bureaucratic establishment, rigid centralization coupled with environmental influence and high turnover are the main impediments to the Jordan\u27s Ministry of Health family planning program

Performance evaluation of a TDMA-based multi-hop communication scheme for reliable delivery of warning messages in vehicular networks

International audienceVehicular Ad hoc NETworks, known as VANETs, are deployed to reduce the risk of road accidents as well as to improve passenger comfort by allowing vehicles to exchange different kinds of data, both between the vehicles themselves and potentially between the vehicles and the infrastructure. One of the major issues in VANETs is the need to improve safety information delivery over long distances. Hence, VANETs require efficient and stable routing protocols that can allow the safety information to be disseminated in a timely manner. We recently proposed TRPM, a TDMA-aware routing protocol for multi-hop communication based on a cross layer approach between the Medium Access Control (MAC) and the routing layers, in which the intermediate vehicles are selected according to their geographic position and the position of their time-slot in the TDMA scheduling frame. The main purpose of this paper is to analyze the efficiency of the TRPM protocol. To do so an analytical model is presented in which expressions are derived to calculate two performance metrics: the delivery delay and packet loss rate. In order to validate the mathematical model and the protocol, a comparison between simulation and analytical results is presented using the network simulator ns-2 and the realistic road traffic simulator MOVE/SUMO

TDMA scheduling strategies for vehicular ad hoc networks: from a distributed to a centralized approach

International audienceVehicular Ad hoc NETworks, known as VANETs, are deployed to reduce the risk of road accidents as well as to improve passenger comfort and safety by allowing vehicles to exchange different kinds of data. Medium Access Control protocols, namely those that are based on TDMA technique play a primary role in providing bounded transmission delay while minimizing data packet loss. However, due to mobility constraints and frequent changes in topology, slot scheduling is a more challenging task in VANETs than in other networks. Many MAC protocols based on TDMA for vehicular networks have been proposed to date. Among them, CTMAC is a centralized scheduling mechanism, while DTMAC, VeMAC and AD-HOCMAC are three distributed TDMA based MAC protocols. In this paper, we evaluate and analyze the performance these four protocols. The scenarios used in the simulation experiments take into account density variation factor that influences protocol performance. We use the MOVE and SUMO tools to generate realistic mobility scenarios. Performance metrics such as access collision, merging collision rate, packet loss and overhead are evaluated using NS-2.34

Performance Impact Analysis of Security Attacks on Cross-Layer Routing Protocols in Vehicular Ad hoc Networks

International audienceRecently, several cross-layer protocols have been designed for vehicular networks to optimize data dissemination by ensuring internal communications between routing and MAC layers. In this context, a cross-layer protocol, called TDMA-aware Routing Protocol for Multi-hop communications (TRPM), was proposed in order to efficiently select a relay node based on time slot scheduling information obtained from the MAC layer. However, due to the constant evolution of cyber-attacks on the routing and MAC layers, data dissemination in vehicular networks is vulnerable to several types of attack. In this paper, we identify the different attack models that can disrupt the cross-layer operation of the TRPM protocol and assess their impact on performance through simulation. Several new vulnerabilities related to the MAC slot scheduling process are identified. Exploiting of these vulnerabilities would lead to severe channel capacity wastage where up to half of the free slots could not be reserved

A game theory‐based route planning approach for automated vehicle collection

International audienceWe consider a shared transportation system in an urban environment where human drivers collect vehicles that are no longer being used. Each driver, also called a platoon leader, is in charge of driving collected vehicles as a platoon to bring them back to some given location (e.g. an airport, a railway station). Platoon allocation and route planning for picking up and returning automated vehicles is one of the major issues of shared transportation systems that need to be addressed. In this paper, we propose a coalition game approach to compute 1) the allocation of unused vehicles to a minimal number of platoons, 2) the optimized tour of each platoon and 3) the minimum energy consumed to collect all these vehicles. In this coalition game, the players are the parked vehicles, and the coalitions are the platoons that are formed. This game, where each player joins the coalition that maximizes its payoff, converges to a stable solution. The quality of the solution obtained is evaluated with regard to three optimization criteria and its complexity is measured by the computation time required. Simulation experiments are carried out in various configurations. They show that this approach is very efficient to solve the multi-objective optimization problem considered, since it provides the optimal number of platoons in less than a second for 300 vehicles to be collected, and considerably outperforms other well-known optimization approaches like MOPSO (Multi-Objective Particle Swarm Optimization) and NSGA-II (Non dominated Sorting Genetic Algorithm)

A Novel Angle-based Clustering Algorithm for Vehicular Ad Hoc Networks

International audienceA vehicular ad hoc network (VANET) is a mobile network in which vehicles acting as moving nodes communicate with each other through an ad hoc wireless network. VANETs have become the core component of Intelligent Transportation Systems (ITS) which aim to improve the road safety and efficiency. Only if the communication scheme used in a VANET is stable can these aims be achieved. Frequent changes in network topology and breaks in communication raise challenging issues in the design of communication protocols for such networks. Currently, clustering algorithms are being used as the control schemes to reduce changes in VANET topologies. However, the design of a clustering algorithm becomes a difficult task in VANETs when there are many road segments and intersections. In this work, we propose an Angle based Clustering Algorithm (ACA), which exploits the angular position and the direction of the vehicles to select the most stable vehicles that can act as cluster heads for a long period of time. The simulation results reveal that ACA significantly outperforms other clustering protocols in terms of cluster stability

Coexistence of IEEE 802.11p and the TDMA-based AS-DTMAC Protocol

International audienceAdvanced vehicular applications such as autonomous driving are leading to a new evolution in vehicular radio access technologies. The Task Group BD on the Next-Generation V2X (NGV) have defined IEEE 802.11bd as the new standard for the Dedicated Short Range Communications (DSRC). Notwithstanding its the promising performances in terms of high reliability, low latency and high throughput, the design must also respect certain specifications, such as coexistence, interoperability, and compatibility with the previous standard. In this article, we study how the IEEE 802.11p protocol could coexist with a TDMA-based protocol named AS-DTMAC, which has recently been proposed to control access in Vehicular Ad Hoc Networks (VANETs). We carry out several analyses to show that the two protocols can coexist by several analysis when both are operating simultaneously on the same network. We also propose a modification of AS-DTMAC to handle the situation where both IEEE 802.11p and AS-DTMAC have to send urgent packets

Optimized trajectories of multi-robot deploying wireless sensor nodes

International audienceA main reason to the growth of wireless sensor networks deployed worldwide is their easy and fast deployment. In this paper we consider deployments assisted by mobile robots where static sensor nodes are deployed by mobile robots in a given area. Each robot must make a tour to place its sensor nodes. All sensor nodes must be placed at their precomputed positions. The Multi-Robot Deploying wireless Sensor nodes problem, called the MRDS problem, consists in minimizing the longest tour duration (i.e. the total deployment duration), the number of robots used and the standard deviation between duration of robots tours. After a formal definition of the MRDS problem, we show how to use a multi-objective version of genetic algorithms, more precisely the NSGA-II algorithm, to solve this multi-objective optimization problem. The solutions belonging to the best Pareto front are given to the designer in charge of selecting the best trade-off taking into account various criteria. We then show how to extend this method to take obstacles into account, which is more representative of real situations

A secure trust-aware cross-layer routing protocol for Vehicular Ad hoc Networks

International audienceVANETs currently represent one of the most prominent solutions that aim to reduce the number of road accident victims and congestion problems while improving the quality of driving. VANETs form a very dynamic open network in which vehicles exchange information and warnings about road situations and other traffic information through several routing protocols, without any intermediate control. However, the absence of a central control makes such a network vulnerable to several types of attack, not only from the outside but also, and mostly, from the interior. This makes their detection by classical security techniques more difficult and requires the development of new techniques to control the information circulating in the network. In this context, a proposed routing protocol called TDMA-aware Routing Protocol for Multi hop communication in Vehicular networks, is vulnerable to security threats, such as Black Hole and Gray Hole attacks, as well as MAC attacks such as Denial of Service (DoS), which lead to a considerable deterioration in the network's performance in terms of packet delivery ratio, end-to-end delays, channel access rate, etc. To mitigate the effect of those attacks, we propose a trust-based model in which each node will establish a trust relationship with its neighbors based on their behaviors during the channel access and packet forwarding process. The simulation results show a significant decrease in the effect of attacks on the performance of the TRPM protocol