A framework for energy based performability models for wireless sensor networks

A novel idea of alternating node operations between Active and Sleep modes in Wireless Sensor Network (WSN) has successfully been used to save node power consumption. The idea which started off as a simple implementation of a timer in most protocols has been improved over the years to dynamically change with traffic conditions and the nature of application area. Recently, use of a second low power radio transceiver to triggered Active/Sleep modes has also been made. Active/Sleep operation modes have also been used to separately model and evaluate performance and availability of WSNs. The advancement in technology and continuous improvements of the existing protocols and application implementation demands continue to pose great challenges to the existing performance and availability models. In this study the need for integrating performance and availability studies of WSNs in the presence of both channel and node failures and repairs is investigated. A framework that outlines and characterizes key models required for integration of performance and availability of WSN is in turn outlined. Possible solution techniques for such models are also highlighted. Finally it is shown that the resulting models may be used to comparatively evaluate energy consumption of the existing motes and WSNs as well as deriving required performance measures

Unravelling technology-acceptance factors influencing farmer use of banana tissue culture planting materials in Central Uganda

Effective management of plant health is fundamental for food and income security to meet the growing demands of local and global markets. This however requires farmers’ adequate access to quality planting materials under the prevailing contextual and psycho-social factors. This study, anchored in the Unified Theory of Acceptance and Use of Technologies, unravels technology-acceptance factors that influence farmers’ intentions to use banana tissue culture planting materials in the control of Banana Xanthomonas Wilt. Data were collected from 248 randomly sampled banana farmers using a structured questionnaire and analyzed using structural equation modelling to examine hypothesized paths in the uptake of banana tissue culture planting materials. Results show that farmer intentions to use tissue culture planting materials are dependent on two constructs: social influence and farmer innovativeness. However, social influence is the main predictor of intentions to use tissue culture planting materials. In particular, farmer innovativeness mediates facilitating conditions and social influence in predicting intentions to use tissue culture planting materials. Thus, this study reveals two factors that influence farmer intentions to use tissue culture planting materials: social influence and farmer innovativeness. The findings imply that social influence and farmer innovativeness are critical in disseminating novel agricultural technologies in Uganda and elsewhere

Project Delivery Systems, Procurement Practices and Implementation of Building Construction Projects in the Kenyan Judiciary

Kenyan population increased from 20 million in 1985 to approximately 47.6 million in 2019 and with it, demand for justice also increased yet the growth did not come with improved Judiciary infrastructure. This attracted the World Bank through the Judicial Performance Improvement Project (JPIP) to fund 30 major court construction projects while the Kenyan Government also funded another 33 such projects from 2013. However, by January, 2020,only 10 projects had been completed and successfully handed over with all the 63 projects being out of the planned time and with variation on the original scope of works.This gave rise to this study that aimed to evaluate the influence of project delivery systems on implementation of building construction projects in the Kenyan judiciary as moderated with the procurement practices. The study was based on general systems theory. Pragmatism paradigm and convergent parallel mixed research design was adopted and proportionate stratified sampling was used to select a population of 234 consisting of judiciary staff, construction staff  and consultants.Primary data was collected through use of questionnaires, interviews and document  content analysis. Reliability was tested using Cronbach’s Alpha while data was analyzed using descriptive statistics which included measures of central tendency. Qualitative data was subjected to thematic analysis to triangulate results derived from quantitative data. Inferential statistics was analyzed by correlation, simple linear regression and multiple regression analysis. Two hypotheses were tested to establish whether there were significant relationships between project delivery systems and implementation of building construction projects in the Kenyan Judiciary, namely  1.H0:  Project delivery systems have no significant relationship with implementation of construction projects in the Kenyan Judiciary and 2.H0: There is no significant moderating influence of procurement practices on the relationship between project delivery systems  and implementation of construction projects in the Kenyan Judiciary.The findings were that there was a significant influence of project delivery systems on the implementation of construction projects in the Kenyan Judiciary and that procurement practices significantly moderated the relationship between project delivery systems and implementation of building construction projects in the Kenyan Judiciary.The slope coefficient was significant when p ≤0.05. The findings of the study will be beneficial to policy makers, project managers in public and private sectors and scholars regarding project delivery attributes on implementation of building construction projects. Keywords:Project delivery Systems, Procurement Practices and Implementation of Building Construction Projects. DOI: 10.7176/CER/13-6-03 Publication date:September 30th 202

User Involvement, Procurement Practices and Implementation of Building Construction Projects in the Kenyan Judiciary

Kenyan population increased from 20 million in 1985 to approximately 47.6 million in 2019 and with it, demand for justice also increased yet the growth did not come with improved Judiciary infrastructure. This attracted the World Bank through the Judicial Performance Improvement Project (JPIP) to fund 30 major court construction projects while the Kenyan Government also funded another 33 such projects from 2013. However, by January, 2020,only 10 projects had been completed and successfully handed over with all the 63 projects being out of the planned time and with variation on the original scope of works.This gave rise to this study that aimed to evaluate the influence of user involvement on implementation of building construction projects in the Kenyan judiciary as moderated with the procurement practices. The study was based on general systems theory. Pragmatism paradigm and convergent parallel mixed research design was adopted and proportionate stratified sampling was used to select a population of 234 consisting of judiciary staff, construction staff  and consultants .Primary data was collected through use of questionnaires, interviews and document  content analysis. Reliability was tested using Cronbach’s Alpha while data was analyzed using descriptive statistics which included measures of central tendency. Qualitative data was subjected to thematic analysis to triangulate results derived from quantitative data. Inferential statistics was analyzed by correlation, simple linear regression and multiple regression analysis. Two hypotheses were tested to establish whether there were significant relationships between project delivery attributes and implementation of building construction projects in the Kenyan Judiciary, namely  1.H0:  User Involvement has no significant relationship with implementation of construction projects in the Kenyan Judiciary and 2.H0: There is a significant moderating influence of procurement practices on the relationship between user involvement  and implementation of building construction projects in the Kenyan Judiciary. The findings were that there was a significant influence of user involvement on the implementation of construction projects in the Kenyan Judiciary and that procurement practices significantly moderated the relationship between user involvement and implementation of building construction projects in the Kenyan Judiciary. The slope coefficient was significant when p ≤0.05. The findings of the study will be beneficial to policy makers, project managers in public and private sectors and scholars regarding project delivery attributes on implementation of building construction projects. Keywords: User involvement, Procurement Practices and Implementation of Building Construction Projects. DOI: 10.7176/EJBM/13-18-12 Publication date:September 30th 202

On the performance, availability and energy consumption modelling of clustered IoT systems

Wireless sensor networks (WSNs) form a large part of the ecosystem of the Internet of Things (IoT), hence they have numerous application domains with varying performance and availability requirements. Limited resources that include processing capability, queue capacity, and available energy in addition to frequent node and link failures degrade the performance and availability of these networks. In an attempt to efficiently utilise the limited resources and to maintain the reliable network with efficient data transmission; it is common to select a clustering approach, where a cluster head is selected among the diverse IoT devices. This study presents the stochastic performance as well as the energy evaluation model for WSNs that have both node and link failures. The model developed considers an integrated performance and availability approach. Various duty cycling schemes within the medium-access control of the WSNs are also considered to incorporate the impact of sleeping/idle states that are presented using analytical modeling. The results presented using the proposed analytical models show the effects of factors such as failures, various queue capacities and system scalability. The analytical results presented are in very good agreement with simulation results and also present an important fact that the proposed models are very useful for identification of thresholds between WSN system characteristics

Census and ear-notching of black rhinos (Diceros bicornis michaeli) in Tsavo East National Park, Kenya

This paper updates the status of the black rhino population in Tsavo East National Park (NP). Data were acquired through aerial counts of the black rhino between 3 and 9 October 2010 using three fixed-wing husky aircrafts and a Bell 206L helicopter in an area of about 3,300 km2. Based on previous sightings of rhinos, the area was divided into 14 blocks, with each block subdivided into 400 m transects. An aircraft flying at about 500 m above the ground was assigned to carry out the aerial survey following these transects within each block. Observers scanned for rhinos about 200 m on either sides of the flight paths. Intensive searches in areas with dense vegetation, especially along the Galana and Voi Rivers and other known rhino range areas was also carried out by both the huskies and the helicopter. The count resulted in sighting of 11 black rhinos. Seven of these individuals were ear notched and fitted with radio transmitters and the horns were tipped off to discourage poaching. Three of the seven captured rhinos were among the 49 animals translocated to Tsavo East between 1993 and 1999. The other four animals were born in Tsavo East. Two female rhinos and their calves were not ear-notched or fitted with transmitters. It is recommended that another count be carried out immediately after the wet season as the rhinos spend more time in the open areas while the vegetation is still green. The repeat aerail count is to include blocks north of River Galana

Deployment challenges and developments in wireless sensor networks clustering

Clustering techniques for wireless sensor networks (WSNs) have been extensively studied and proven to improve the network lifetime, a primary metric, used for performance evaluation of sensor networks. Although introduction of clustering techniques has the potential to reduce energy consumption and extend the lifetime of the network by decreasing the contention through either power control or node scheduling, scalability remains an issue. Therefore, the optimality of the cluster size still needs to be thoroughly investigated. In this paper, a single cluster head (CH) queuing model is presented. Using an event based simulation tool (Castalia), key issues that affect the practical deployment of clustering techniques in wireless sensor networks are analysed. These include identifying the bottlenecks in terms of cluster scalability and predicting the nature of data packets arrival distribution at the CH. Results presented show that this analysis can be used to specify the size of a cluster, when a specific flow of data is expected from the sensing nodes based on a particular application and also the distribution of the inter-arrival times of data packets at the CH follows exponential distribution

Packet arrival analysis in wireless sensor networks

Distributed sensor networks have been discussed for more than 30 years, but the vision of Wireless Sensor Networks (WSNs) has been brought into reality only by the rapid advancements in the areas of sensor design, information technologies, and wireless networks that have paved the way for the proliferation of WSNs. The unique characteristics of sensor networks introduce new challenges, amongst which prolonging the sensor lifetime is the most important. WSNs have seen a tremendous growth in various application areas including health care, environmental monitoring, security, and military purposes despite prominent performance and availability challenges. Clustering plays an important role in enhancement of the life span and scalability of the network, in such applications. Although researchers continue to address these grand challenges, the type of distributions for arrivals at the cluster head and intermediary routing nodes is still an interesting area of investigation. Modelling the behaviour of the networks becomes essential for estimating the performance metrics and further lead to decisions for improving the network performance, hence highlighting the importance of identifying the type of inter-arrival distributions at the cluster head. In this paper, we present extensive discussions on the assumptions of exponential distributions in WSNs, and present numerical results based on Q-Q plots for estimating the arrival distributions. The work is further extended to understand the impact of end-to-end delay and its effect on inter-arrival time distributions, based on the type of medium access control used in WSNs. Future work is also presented on the grounds that such comparisons based on simple eye checks are insufficient. Since in many cases such plots may lead to incorrect conclusions, demanding the necessity for validating the types of distributions. Statistical analysis is necessary to estimate and validate the empirical distributions of the arrivals in WSNs

Does the assumption of exponential arrival distributions in wireless sensor networks hold?

Wireless Sensor Networks have seen a tremendous growth in various application areas despite prominent performance and availability challenges. One of the common configurations to prolong the lifetime and deal with the path loss phenomena having a multi-hop set-up with clusters and cluster heads to relay the information. Although researchers continue to address these challenges, the type of distribution for arrivals at the cluster head and intermediary routing nodes is still an interesting area of investigation. The general practice in published works is to compare an empirical exponential arrival distribution of wireless sensor networks with a theoretical exponential distribution in a Q-Q plot diagram. In this paper, we show that such comparisons based on simple eye checks are not sufficient since, in many cases, incorrect conclusions may be drawn from such plots. After estimating the Maximum Likelihood parameters of empirical distributions, we generate theoretical distributions based on the estimated parameters. By conducting Kolmogorov-Smirnov Test Statistics for each generated inter-arrival time distributions, we find out, if it is possible to represent the traffic into the cluster head by using theoretical distribution. Empirical exponential arrival distribution assumption of wireless sensor networks holds only for a few cases. There are both theoretically known such as Gamma, Log-normal and Mixed Log-Normal of arrival distributions and theoretically unknown such as non-Exponential and Mixed cases of arrival in wireless sensor networks. The work is further extended to understand the effect of delay on inter-arrival time distributions based on the type of medium access control used in wireless sensor networks

Molecular Markers for Genetic Diversity Studies in African Leafy Vegetables

African leafy vegetables are becoming important crops in tackling nutrition and food security in many parts of sub-Saharan Africa, since they provide important micronutrients and vitamins, and help resource-poor farm families bridge lean periods of food shortage. Genetic diversity studies are essential for crop improvement programmes as well as germplasm conservation efforts, and research on genetic diversity of these vegetables using molecular markers has been increasing over time. Diversity studies have evolved from the use of morphological and biochemical markers to molecular markers. Molecular markers provide valuable data, since they detect mostly selectively neutral variations at the DNA level. They are well established and their strengths and limitations have been described. New marker types are being developed from a combination of the strengths of the basic techniques to improve sensitivity, reproducibility, polymorphic information content, speed and cost. This review discusses the principles of some of the established molecular markers and their application to genetic diversity studies of African leafy vegetables with a main focus on the most common Solanum, Amaranthus, Cleome and Vigna species.BMBF/HORTINLEABM