Radio over fiber is becoming an increasingly important technology for the wireless market since it introduces a good data transmission rate and large bandwidth. We have implemented a bidirectional radio over fiber (ROF) system. It is combination of SCM-ROF and optical wavelength division multiplexing (WDM) techniques to simplify the access network architecture. The combination of two different types has been performed to provide high bit data rate and wide bandwidth in cellular communication. The system allows different Base Stations (BS's) to be fed by a common fiber. Different wavelength channels can be allocated to different BSs depending on user requirements. This paper consists of two parts: I. Introduction of Radio of Fiber technology & methodology II. Quality parameter & Challenges for Implementation. Wireless communication was one of the paramount ways in term ofhigh bandwidth data communication. Technology like microwave, wireless, optical communication & their combination are used and have improved the performance of the communication. Radio over Fiber technology (RoF), an Integration of microwave and optical communication is an essential technology for the provision of unmetered access to broadband wireless communications. For the future provisions of broadband, multimedia the radio over fibre systems are a good alternative. RoF systems are used basically because of their low loss and extremely wide bandwidth and robustness. Radio over fibre can use millimetre waves and serve as a high speed wireless local or personal area network. In this paper various parts of the Radio over fibre systems are studied, ROF is an analog optical link transmitting optical carrier modulated by the radio frequency signal. This technique facilitates to transmit radio frequency signal through the optical fiber in downlink and uplink
Salinity is one of the major constraints for crop yield because it limits plant growth and reduces both the crop yield and the use of agricultural land. Increased salt tolerance requires new genetic sources of salt tolerance, and more efficient techniques for identifying salt-tolerant germplasm. The DD-RT-PCR technique (Differential Display-Reverse Transcription- Polymerase Chain Reaction) is one of these techniques, which are able to compare and identify changes in gene expression at the mRNA and the cDNA levels between any pair of contrasting genotypes. It was performed using mRNA extracted from the aerial part of two contrasting Tunisian barley genotypes (Sabra: tolerant and kelibia: sensitive accessions) subjected or not to salt stress. In this study, we have used this technique (RT-PCR) to identify cDNAs corresponding to transcripts up- or down-regulated by salt stress in barley. Within 18 primer combinations (3 Oligod(T) x 6 arbitrary primers), we have identified a total of 58 differential display products which are over-expressed or disappeared in stressed samples indicating a qualitative and quantitative difference in the gene expression. ***The up-expressed fragment were eluted and sequenced at the Pasteur Institute of Tunis and then compared to those of the bank data (Genbank Barley) to determine sequences having an optimal alignment with the query. The result was the identification of many salt-responsive transcripts fragments corresponding to hypothetic proteins (T17F15.140-like and Mei2-like), to some proteins involved in oxidative and heat stress (GAD1= Glutamic Acid Decarboxylase) or to proteins involved in the resistance to pathogens (ß-1,3-glucanase) and to anionic flux resistance. But the most important finding is the identification of genes encoding the Na+/H+ antiporter which sequestrate sodium into vacuole in the tolerant barley genotype. These two last transcripts encoding the sequestration of Na could be used as markers for selecting salt tolerant genotypes in the program of varietals improvement to salt stress tolerance.
Le coefficient de mortalité totale (Z, an-1) de l'espèce Istiophorus albicans capturée à partir de la pêcherie artisanale maritime de Côte d'Ivoire (Afrique de l'ouest) est déterminé, grâce à la méthode des courbes de capture selon les longueurs. Ces taux de mortalité sont estimés à partir de distributions de fréquences de tailles d'une longue série de données (1988-2007). Le taux de mortalité totale le plus élevé (Z=8,97 an-1) est enregistré durant la période 2006 à 2007, et le faible (Z=4,12 an-1) de 1991 à 1993. Le rapport Z/K est compris entre 3,68 et 9,74. Ce résultat indique que la population exploitée est largement dominée par la mortalité. De plus, ce résultat suggère également un niveau d'exploitation élevé La longueur infinie (L?) est restée constante et égale à 231 cm de 1988 à 2005. Cependant, de 2006 à 2007 l'on enregistre une valeur de 241,5 cm.
This paper reports on a qualitative study which explored the beliefs of a sample of foreign language teachers about school in Algeria within a context of curriculum reforms. It was found that the participants believed that the Algerian school was generally a site of power and domination; that there was a drastic lack of resources; that students were unmotivated; that parents were disengaged; and that school administration was bureaucratic. The paper concludes that curriculum reforms in Algeria were not paralleled with social, economic and political reforms of educational institutions. It is suggested that there is an urgent need to equip schools with resources to make them adequately prepared for the effective implementation of the new curriculum. However, in the long term, it is suggested that policy-makers should promote a culture of active participation of all those involved in education, mainly the teachers and parents, towards improving the current situation of schools in Algeria, and ultimately, of the educational system.
Despite their fundamental socio-economic responsibilities, rural women still have less access to knowledge, assets, services and participation in decision-making. These inequalities affect their ability to carry out critical roles in their communities leading to rural poverty. In Kenya, women groups form the majority of local initiatives. Although women groups are the solution to the local problems, there is little support they receive from the government and other development stakeholders, hence their inability to address rural problems. Besides, there are limited studies particularly in Kenya on women groups' contribution to rural development. This paper is a portion of the outcome of an empirical descriptive study conducted in Nyamusi Division in Nyamira County by the authors. The sample was drawn from ten registered women groups and fifteen informal women groups in the study area. The unit of analysis was a women group. This paper critically examines the relationship that exist between rural community-based approaches (in this case-women groups) and rural development. It also looks at the barriers that hamper women's development efforts in community interventions. This paper concludes that if given opportunity, women have the potential to change their own socio-economic status as well as that of the communities in which they live in for the reason that women groups act as an effective instrument for rural development. Once women groups have sufficient solidarity, experience and unity of purpose in their undertakings, rural development is achieved. This paper recommends policy frameworks that not only promote community-based approaches for rural development, but also encourage sustainability and equal participation of all genders in development.
In order to extend areas usable in cities, migrants to cities, often reshape the natural landscapes in various forms. In some cases, they reduce hills, reclaim beach regions, fill valleys and wetlands, and sometimes encroach on river valleys not minding the consequences on the environment. These cultural ways of increasing usable lands have some negative impact on the urban physical environment. The major negative impact is change in the micro-climate of urban environment which manifest in various forms including flooding. Based on the above impact, the paper identified the consequences of flooding in Akure and determines ways by which its menace on traffic congestion could be reduced. Structured questionnaire was administered to residents of Akure living within 200 meter radius to areas where flash flood had been witnessed. Result shows positive correlation between flash flood and traffic congestions in the city. Similarly, accident rates were found to increase during heavy downpour in many of the flood hot spots as many vehicles struggle for right of way. Flash flood on traffic corridor was noted to influence numbers of stranded vehicles in the pool of water. The paper recommends regular clearance of drainages at the on-set of rainy seasons especially in areas prone to flooding. Property developers should ensure that gutters are provided in newly developed areas of cities. The paper also advocated the creation of environmental awareness through both formal and Informal forms of education on how to dispose solid as the hallmark of managing traffic in flooded environment in the study area.
In this paper an attempt has been made for analysis of voltage stability using Hopf bifurcation in power system and a new formula for computing and loading of any power system is proposed with the help of using Bifurcation technique using VST Toolbox. Minimum Voltage of the feeders can also be maintained by allowing the feeders to take load growth up to a specific period of time. The critical values of total real power load (TPL) and total reactive power load (TQL) for constant power, constant current, constant impedance, composite as well as exponential load modeling is derived out for the substation voltage of power system. When any parameter changes, the stable Equilibrium points may lose its dynamic stability at the feasibility boundary, which is caused by one of three different local bifurcation the singularity induced bifurcation, saddle-node and Hopf bifurcation. After solving the Differential Algebraic Equation is calculated for different power condition using iterative process. Those results will help to find types of bifurcation, and after that to using MATLAB coding to analyzing HOPF bifurcation static and dynamic process with the help of two simple indices we detected oscillatory problems in power systems, based on the system state matrix as well as an augmented system matrix.
Waste management is the "generation, prevention, characterization, monitoring, treatment, handling, reuse and residual disposition of solid wastes. Waste management in Tunisia is currently one of the priorities of environmental protection and is one of the main pillars of sustainable development. Thus, Tunisia has opted for a comprehensive and progressive policy of environmental protection in order to cope with the current state of the object affected by the strong economic growth and the environment rapid urban expansion in recent years. The area of waste management has received attention currently given the quantity produced changes in the multiplicity of forms and aspects of pollution caused by waste, and limited resources used in the field of solid waste management. During this, our research has been devoted to the study of the phenomenon of industrial waste management by recycling in Tunisia. We used a model based on a time series analysis for a period of 12 years (2000-2011) model. We used the software STATA12 to empirical validation. In addition, we estimated the ability to manage industrial waste recycling based on variables related to the business of recycling industrial waste, variables related to the intervention of Tunisia policy in the management of industrial waste recycling and macroeconomic indicators.
Fuzzy goal programming (FGP) is, the most widely used method for solving multi-objective real-world decision making problems. In this paper, we focus on fuzzy goal programming (FGP) formulation for solving fuzzy multi objective fractional goal programming problems, which will easily help the decision makers to set the correct policy corresponding to their goals. Furthermore, the proposed concept of membership goals gives desirable and more realistic solution than the existing FGP methods in the sense that the goals are achieved according to the real case needs. Finally, for illustration, one example is used to demonstrate the correctness and usefulness of the proposed analysis of FGP method.
The use of psychoactive substances among street children for survival has been a prevalent problem in most urban centres in Kenya. Eldoret Municipality is one of the regions that has been affected by generally high numbers of street children who in particular capitalize on the use of psychoactive substances to survive on the streets. This paper is an outcome of a study that was conducted in Eldoret Municipality and partly examined the patterns and dynamics of psychoactive substance use among street children in the Municipality. The focus on the Municipality was based on the fact that it is a politically hot spot town and has an ever growing number of street children. This is largely attributed to factors such as poverty, HIV/AIDS, tribal clashes and/or wars, emergence and expansion of low income estates (slums). The research on which this paper draws adopted an ethnographic design commonly used in studies dealing with network analysis or organizational structures. Data was collected by means of semi-structured interviews and focus group discussions with street children and service providers. The study found that glue sniffing and use of other substances like, bhang (Marijuana), alcohol (local brew), smoking and chewing tobacco were most used by the street children and hence, thwarting efforts of rehabilitation and reintegration of street children with their families and/or caregivers. From the findings of the study, there has been little achievement in rehabilitation and reintegration of street children with their families particularly those addicted to various psychoactive substance abuse. This paper concludes that the principal barrier to prevention of psychoactive substance use has been the failure by the government and street children agencies to implement an all-inclusive and sustainable strategy for street children's rehabilitation and reintegration. The authors recommend that the government, health service providers and street children agencies should adopt a holistic health and rehabilitation approach for street children population. This shall lead to eventual removal of street children from the streets not only in Eldoret Municipality, but also in all urban centres in the country.