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Although food crop yields per hectare have generally been increasing in Cameroon since 1961, the food price crisis of 2008 and the ensuing social unrest and fatalities raised concerns about the country's ability to meet the food needs of its population. This study examines the country's potential for increasing crop yields and food production to meet this food security challenge. Fuzzy set theory
Basal ecosystem respiration rate (BR), the ecosystem respiration rate at a given temperature, is a common and important parameter in empirical models for quantifying ecosystem respiration (ER) globally. Numerous studies have indicated that BR varies in space. However, many empirical ER models still use a global constant BR largely due to the lack of a functional description for BR. In this study,
The satellite-derived normalized difference vegetation index (NDVI), which is used for estimating gross primary production (GPP), often includes contributions from both mosses and vascular plants in boreal ecosystems. For the same NDVI, moss can generate only about one-third of the GPP that vascular plants can because of its much lower photosynthetic capacity. Here, based on eddy covariance measur
Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. H
In the Sudano-Sahelian areas of Africa droughts can have serious impacts on natural resources, and therefore land surface moisture is an important factor. Insufficient conventional sites for monitoring land surface moisture make the use of Earth Observation data for this purpose a key issue. In this study we explored the potential of using reflectance data in the Red, Near Infrared (NIR), and Shor
Extensive measurements of soil surface (including vegetation cover) CO2 efflux were carried out on 80 positions at four different forest sites (Sweden, Germany, Czech Republic and Italy) using a closed dynamic chamber technique. The period of measurement was 4-5 consecutive days per site. Two approaches were used to analyze the measured data, the Q(10) parameter and the Arrhenius relationship. Bas
Resource optimization mechanisms, as admission control and traffic management, require accurate performance models that capture the dynamics of the system during high loads. The main objective of this paper is to develop an accurate performance model for database servers in a telecommunication service management system. We investigate the use of a server model with load dependency. Concurrent requ
Many student–industry activities have emerged in recent years, and universities have invested considerable time and energy in designing and implementing such collaboration models. However, as models differ significantly, student–industry activities should not all be bundled together. This paper examines student–industry activities conducted as integral parts of engineering study programmes. These
Student–industry activities are often heralded as win–win–win activities in which students gain knowledge of their future professional fields, companies access student knowledge, and universities both offer students stimulating learning opportunities and strengthen ties with industry. Student–industry projects can be defined as an active learning methodology characterized by pedagogical values suc
Robotic force control refers to the control and programmable specification of the interaction forces between a robot end effector and the work object, where either the end effector or the work object is attached to the robot manipulator. A rudimentary approach is to consider the joint torques and controlled variables, and then to compute those torques such that a presumably rigid manipulator effec
The colors and contrasts of the nocturnal world are just as rich as those found in the diurnal world. This chapter describes a recent biomimetic advance inspired by the visual systems of nocturnal insects. Since the underlying principles of both animal and camera vision are similar, it is natural to try to mimic the neural processes of nocturnal animals in order to construct efficient computer vis
Response time is a measure of quality of service in com- puter systems. Estimation techniques, suitable for support systems for mobile phone systems, are explored. These sys- tems are complex queueing systems with large databases. The trac generated by users and system adminstrators changes rapidly, some loads can be measured other cannot. Attempts to capture all details give models that are not s
Today’s cloud data center infrastructures are not even near being able to cope with the enormous and rapidly varying capacity demands that will be reality in a near future. So far, very little is understood about how to transform today’s data centers (being large, power-hungry facilities, and operated through heroic efforts by numerous administrators) into a self-managed, dynamic, and dependable i
Syfte Corporate Social Responsibility (CSR) är ett begrepp som används flitigt inom det svenska näringslivet. Forskningen inom ämnet är dock inte lika omfattande och därför anser jag att det finns ett behov att ge diskussionen ett svenskt perspektiv. Syftet med föreliggande arbete är att beskriva CSR med hjälp av kommunikationsvetenskapliga faktorer, för att ge en vidare förståelse av begreppet. F
Terrestrial gross primary production (GPP) is the largest global CO2 flux driving several ecosystem functions. We provide an observation-based estimate of this flux at 123 +/- 8 petagrams of carbon per year (Pg C year(-1)) using eddy covariance flux data and various diagnostic models. Tropical forests and savannahs account for 60%. GPP over 40% of the vegetated land is associated with precipitatio
A single antenna based virtual antenna array at the receiver can be used to find direction of different incoming radio signals impinging at the receiver. In this paper, we investigate the performance of random 3D virtual antenna arrays for DoA estimation. We have computed a Cramer-Rao Lower Bound (CRLB) for DoA estimation if the true antenna positions are not known, but these are estimated with an
Unusually high CO2 concentrations were frequently observed during stable nights in late summer 2006 at the CarboEurope-Integrated Project (CEIP) forest site in Norunda, Sweden. Mean CO2 concentrations in the layer below the height of the eddy-covariance measurement system at 30 m reached up to 500 mu mol mol(-1) and large vertical and horizontal gradients occurred, leading to very large advective
The Mobile Service Support system (MSS), which Ericsson AB develops, handles the setup of new subscribers and services into a mobile network. Experience from deployed systems show that traffic monitoring and control of the system will be crucial for handling overload situations that may occur at sudden traffic surges. In this paper we identify and explore some important control challenges for this
Advanced telecommunication applications are often based on a multi-tier architecture, with application servers and database servers. With a rapidly increasing development of cloud computing and data centers, characterizations of the dynamics for database servers during changing workloads will be a key factor for analysis and performance improvements in these applications. We propose a multi-step a
