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Search Results: 1 - 10 of 5489 matches for " Diana Besem Tambe "
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GIS-Hydrogeochemical Model of the Yaoundé Fractured Rock Aquifer, Cameroon: Aquifer Setting, Seasonal Variations in Groundwater-Rock Interaction and Water Quality  [PDF]
Richard Ayuk II Akoachere, Omabgemi Omoloju Yaya, Sonia Ebot Egbe, Thomson Areakpoh Eyong, Bihmimihney Nelly Nji, Diana Besem Tambe
Journal of Geoscience and Environment Protection (GEP) , 2019, DOI: 10.4236/gep.2019.75018
Abstract:
This study of the gneiss-fractured-rock aquifer in Yaoundé capital of Cameroon determines: the aquifer setting-flow systems, the aquifer type, seasonal variations in rock-water interactions, evolution of the hydrogeochemical processes, physicochemical parameters and the suitability for domestic-agro-industrial use of the groundwater. Physicochemical field tests were carried out on 445 wells during four seasons for EC, pH, TDS, Temperature and static water level from July 2016 to May 2017. 90 well samples were analyzed 45 samples per season: wet/dry. 38 borewell logs were used together with structural data to determine the aquifer setting. The field physico-chemical and laboratory analysis data of well samples were mounted unto various GIS software platforms: Global mapper, AqQa, Aquachem, Rockworks, Logplot7, Surfer and ArcGIS, to get indices/parameters/figures, by use of Durov’s, Piper’s and Gibbs diagrams, Water quality index WQI, USSL ratio, Sodium Absorption ratio SAR, Percent sodium %Na, Kelly Ratio KR, Magnesium Absorption Ratio MAR, Total Hardness TH, Residual Sodium Carbonate RSC and Permeability Index PI that were determined. The process of groundwater ions acquisition is three-fold: by recharge through atmospheric precipitation, by ion exchange/simple dissolution between the rock-groundwater and by groundwater mixing in its flow path. Water types are Ca-HCO3, Mg-HCO3 and Mg-Cl while hydrogeochemical facies are Ca-Mg-HCO3 and Ca-Mg-Cl-SO4. Most water samples are
Seasonal Variations in Groundwater of the Phreatic Aquiferous Formations in Douala City-Cameroon: Hydrogeochemistry and Water Quality  [PDF]
Richard Ayuk Akoachere, Sonia Ebot Egbe, Thomson Areapkoh Eyong, Sophie Ngomune Edimo, Simon Ngomba Longonje, Diana Besem Tambe, Nji Bihmimihney Nelly
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105328
Abstract:
This study was to determine the seasonal variations of groundwater, the influence of the rock formations on the groundwater solute chemistry and groundwater domestic-agro-industrial quality using hydrogeochemical tools and physicochemical parameters; Ionic ratios, Gibbs diagrams, Piper diagrams, Durov diagrams and water quality indices. From physicochemical parameters; in the rainy season, pH ranged from, 4.6-7.1; EC, 0.023-1.63 mS/cm; Temperature, 26.3-290C andTDS, 0.015-1.09 mg/L and in the dry season pH ranged from 5-7.2; EC, 0.01-1.61 mS/cm; Temperature, 24.4-29.50C andTDS, 0.01-1.08 mg/L. Forty groundwater samples; 20 per season, wet and dry were analysed. Themajor ions fell below WHO acceptable limits for both seasons. The sequences of abundance of major ions were, Ca2 >K >Mg2 >NH4 >Na , HCO3->Cl->SO42->NO3->HPO42- in wet season and Ca2 >Mg2 >K >Na >NH4 , HCO3->Cl->SO42->HPO42->NO3- in dry season. Ion-exchange, simple dissolution and uncommon dissolution processes determined groundwater character. Groundwater ionic content was as a result of ion exchange from rock-weathering. Water types are; MgCl and MgHCO3 in both seasons. Hydrogeochemical facies are; Ca-Mg-Cl-SO4, characteristic of groundwater some distance along its flow path and Ca-Mg-HCO3, characteristic of freshly recharged groundwater from precipitation. The groundwater indices of; Sodium Percent (% Na), Residual Sodium Carbonate (RSC) , Kelley’s ratio (KR), Sodium Adsorption Ratio (SAR), Electrical Conductivity (EC), Total Dissolved Solid (TDS), USSL? and Wilcox index were determined, evaluated and found to be suitable for agro-industrial uses in all seasons. Permeability Index (PI) , Water quality index (WQI) and Magnesium Adsorption Ratio (MAR) were not suitable in some areas and in some seasons.
Towards Flexible Teamwork
M. Tambe
Computer Science , 1997,
Abstract: Many AI researchers are today striving to build agent teams for complex, dynamic multi-agent domains, with intended applications in arenas such as education, training, entertainment, information integration, and collective robotics. Unfortunately, uncertainties in these complex, dynamic domains obstruct coherent teamwork. In particular, team members often encounter differing, incomplete, and possibly inconsistent views of their environment. Furthermore, team members can unexpectedly fail in fulfilling responsibilities or discover unexpected opportunities. Highly flexible coordination and communication is key in addressing such uncertainties. Simply fitting individual agents with precomputed coordination plans will not do, for their inflexibility can cause severe failures in teamwork, and their domain-specificity hinders reusability. Our central hypothesis is that the key to such flexibility and reusability is providing agents with general models of teamwork. Agents exploit such models to autonomously reason about coordination and communication, providing requisite flexibility. Furthermore, the models enable reuse across domains, both saving implementation effort and enforcing consistency. This article presents one general, implemented model of teamwork, called STEAM. The basic building block of teamwork in STEAM is joint intentions (Cohen & Levesque, 1991b); teamwork in STEAM is based on agents' building up a (partial) hierarchy of joint intentions (this hierarchy is seen to parallel Grosz & Kraus's partial SharedPlans, 1996). Furthermore, in STEAM, team members monitor the team's and individual members' performance, reorganizing the team as necessary. Finally, decision-theoretic communication selectivity in STEAM ensures reduction in communication overheads of teamwork, with appropriate sensitivity to the environmental conditions. This article describes STEAM's application in three different complex domains, and presents detailed empirical results.
ANALGESIC ACTIVITY OF CARALLUMA ADSCENDENS ROXB. (AERIAL PARTS)
Tambe D.A.
International Journal of Pharmaceutical Research and Development , 2010,
Abstract: In the present study, Petroleum ether, Ethyl acetate and Methanolic extracts of Caralluma adscendens aerial parts at the doses of 100 and 200 mg/kg was evaluated for the Analgesic activity using the hot plate and acetic acid induced abdominal constrictions in mice. Caralluma adscendens aerial parts extract showed significant Analgesic properties in all the models studied.
Entry complications in laparoscopic surgery
Krishnakumar S,Tambe P
Journal of Gynecological Endoscopy and Surgery , 2009,
Abstract: Objective: To review the complications associated with laparoscopic surgery and provide clinical direction regarding the best practice based on the best available evidence. Options: The laparoscopic entry techniques and technologies reviewed include the classic pneumoperitoneum (Veress/trocar), the open (Hasson), the direct trocar insertion, the use of disposable shielded trocars, radially expanding trocars and visual entry systems. Evidence: Medline, Pubmed and Cochrane Databases were searched for English language articles published before December 2008. Conclusions: It is an evidence based fact that minimal access surgery is superior to conventional open surgery since this is beneficial to the women, community and the healthcare system.Over the past 50 years, many techniques, technologies and guidelines have been introduced to eliminate the risks associated with laparoscopic entry. No single technique or instrument has been proved to eliminate laparoscopic entry associated injury. Proper evaluation of the women, supported by surgical skills and good knowledge of the technology and instrumentation is the keystone to safe access and prevention of complications during laparoscopic surgery.
Hybrid BDI-POMDP Framework for Multiagent Teaming
R. Nair,M. Tambe
Computer Science , 2011, DOI: 10.1613/jair.1549
Abstract: Many current large-scale multiagent team implementations can be characterized as following the belief-desire-intention (BDI) paradigm, with explicit representation of team plans. Despite their promise, current BDI team approaches lack tools for quantitative performance analysis under uncertainty. Distributed partially observable Markov decision problems (POMDPs) are well suited for such analysis, but the complexity of finding optimal policies in such models is highly intractable. The key contribution of this article is a hybrid BDI-POMDP approach, where BDI team plans are exploited to improve POMDP tractability and POMDP analysis improves BDI team plan performance. Concretely, we focus on role allocation, a fundamental problem in BDI teams: which agents to allocate to the different roles in the team. The article provides three key contributions. First, we describe a role allocation technique that takes into account future uncertainties in the domain; prior work in multiagent role allocation has failed to address such uncertainties. To that end, we introduce RMTDP (Role-based Markov Team Decision Problem), a new distributed POMDP model for analysis of role allocations. Our technique gains in tractability by significantly curtailing RMTDP policy search; in particular, BDI team plans provide incomplete RMTDP policies, and the RMTDP policy search fills the gaps in such incomplete policies by searching for the best role allocation. Our second key contribution is a novel decomposition technique to further improve RMTDP policy search efficiency. Even though limited to searching role allocations, there are still combinatorially many role allocations, and evaluating each in RMTDP to identify the best is extremely difficult. Our decomposition technique exploits the structure in the BDI team plans to significantly prune the search space of role allocations. Our third key contribution is a significantly faster policy evaluation algorithm suited for our BDI-POMDP hybrid approach. Finally, we also present experimental results from two domains: mission rehearsal simulation and RoboCupRescue disaster rescue simulation.
A Survey of Mycorrhizal Colonization in the 50-ha Korup Forest Dynamic Plot in Cameroon  [PDF]
Eneke Esoeyang Tambe Bechem, George Bindeh Chuyong, Belinda Tengu Fon
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.510155
Abstract:

A study was carried out in the 50-ha Korup Forest Dynamic Plot in South West Cameroon, to evaluate the diversity of mycorrhizal associations as well as to determine the effect of habitat types on the type of mycorrhizal association. A total of 781 individual trees belonging to 51 families, 165 genera and 252 tree species, were sampled from the four habitat types found in the plot: low drier, hill slope, ridge top and wetland complexes. In each habitat type, all stems ≤ 1 cm depth at breast height had already been tagged, measured, mapped and identified to the species level. Root samples were collected, cleared, stained and examined microscopically for mycorrhizal type. Of the total number of species sampled, 248 (98.41%) formed mycorrhizal associations with only 4 (1.59%) being non mycorrhizal. For mycorrhizal trees, 232 (93.55%) formed exclusively arbuscular mycorrhiza, 10 (4.03%) formed ectomycorrhiza, while 6 (2.42%) formed both ecto- and arbuscular mycorrhiza. The ridge top harbored the least number (152) of mycorrhizal trees while the low drier area harbored the most number (266) of mycorrhizal trees. Although habitat effect was not significant in influencing mycorrhizal colonization of tree species, some tree species did show aggregated patterns in particular habitats.


The Communicative Multiagent Team Decision Problem: Analyzing Teamwork Theories and Models
D. V. Pynadath,M. Tambe
Computer Science , 2011, DOI: 10.1613/jair.1024
Abstract: Despite the significant progress in multiagent teamwork, existing research does not address the optimality of its prescriptions nor the complexity of the teamwork problem. Without a characterization of the optimality-complexity tradeoffs, it is impossible to determine whether the assumptions and approximations made by a particular theory gain enough efficiency to justify the losses in overall performance. To provide a tool for use by multiagent researchers in evaluating this tradeoff, we present a unified framework, the COMmunicative Multiagent Team Decision Problem (COM-MTDP). The COM-MTDP model combines and extends existing multiagent theories, such as decentralized partially observable Markov decision processes and economic team theory. In addition to their generality of representation, COM-MTDPs also support the analysis of both the optimality of team performance and the computational complexity of the agents' decision problem. In analyzing complexity, we present a breakdown of the computational complexity of constructing optimal teams under various classes of problem domains, along the dimensions of observability and communication cost. In analyzing optimality, we exploit the COM-MTDP's ability to encode existing teamwork theories and models to encode two instantiations of joint intentions theory taken from the literature. Furthermore, the COM-MTDP model provides a basis for the development of novel team coordination algorithms. We derive a domain-independent criterion for optimal communication and provide a comparative analysis of the two joint intentions instantiations with respect to this optimal policy. We have implemented a reusable, domain-independent software package based on COM-MTDPs to analyze teamwork coordination strategies, and we demonstrate its use by encoding and evaluating the two joint intentions strategies within an example domain.
Robust Agent Teams via Socially-Attentive Monitoring
G. A. Kaminka,M. Tambe
Computer Science , 2011, DOI: 10.1613/jair.682
Abstract: Agents in dynamic multi-agent environments must monitor their peers to execute individual and group plans. A key open question is how much monitoring of other agents' states is required to be effective: The Monitoring Selectivity Problem. We investigate this question in the context of detecting failures in teams of cooperating agents, via Socially-Attentive Monitoring, which focuses on monitoring for failures in the social relationships between the agents. We empirically and analytically explore a family of socially-attentive teamwork monitoring algorithms in two dynamic, complex, multi-agent domains, under varying conditions of task distribution and uncertainty. We show that a centralized scheme using a complex algorithm trades correctness for completeness and requires monitoring all teammates. In contrast, a simple distributed teamwork monitoring algorithm results in correct and complete detection of teamwork failures, despite relying on limited, uncertain knowledge, and monitoring only key agents in a team. In addition, we report on the design of a socially-attentive monitoring system and demonstrate its generality in monitoring several coordination relationships, diagnosing detected failures, and both on-line and off-line applications.
An interview with Diana from Libya
Diana
International Journal of Inclusive Democracy , 2011,
Abstract: IJID Note:The interviewer will be referred below as JR and the interviewee as DL. Both the interviewer as well as the interviewee preferred not to reveal publicly their names for security reasons.JR’s Notes:In the 1980s, when Gaddafi’s policies veered to the left and nationalization of the economy became widespread, Diana father’s business was severely affected. So her own background is not what one might expect of someone who now is speaking up passionately against the NATO assault on Libya…Unfortunately, most mainstream western journalists seem interested only in hearing from anti-Gaddafi Libyans. So it is the fact that westerners continue to get a one-sided picture of Libya which helps support the case for NATO bombing. Here’s another side to the story…
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