Facility Location Problems: Models, Techniques, and Applications in Waste Management

This paper presents a brief description of some existing models of facility location problems (FLPs) in solid waste management. The study provides salient information on commonly used distance functions in location models along with their corresponding mathematical formulation. Some of the optimization techniques that have been applied to location problems are also presented along with an appropriate pseudocode algorithm for their implementation. Concerning the models and solution techniques, the survey concludes by summarizing some recent studies on the applications of FLPs to waste collection and disposal. It is expected that this paper will contribute in no small measure to an integrated solid waste management system with specific emphasis on issues associated with waste collection, thereby boosting the drive for e�ective and e�cient waste collection systems. The content will also provide early career researchers with some necessary starting information required to formulate and solve problems relating to FLP

An Improved Location Model for the Collection of Sorted Solid Waste in Densely Populated Urban Centres

This paper presents a facility location model for improving the collection of solid waste materials. The model is especially suitable for densely populated regions with several housing units as well as encourages initial sorting of wastes. Each individual house in the collection area is designated a customer, with randomly selected customers comprising the set of candidate hubs. The fundamental feature of the model is to group the customers into clusters by assigning each customer (house) to the nearest hub. Each cluster is then assigned to exactly one waste collection site drawn from the set of potential collection locations. The objective is to minimize the total number of activated waste collection sites such that all the customers’ requests are satisfied without violating the capacity limit of each site. A simple Lagrangian relaxation heuristic is developed for the problem and solved with the CPLEX solver on the AMPL platform to find a feasible solution. Results from the numerical implementation of model show the model is efficient and competitive with existing solid waste collection facility location model

A Review of Local Factors Affecting Solid Waste Collection in Nigeria

The knowledge of local and regional factors that affect effective solid waste collection plays an important role in choosing appropriate technology. Waste collection has grown to become a major challenge demanding daily response from waste managers and it becomes inevitable to provide stakeholders with necessary information to aid key decision-making. This paper provides a comprehensive and detailed review of local-based factors that affect waste collection in Nigeria. Literature study and on-site observation were used for getting theoretical and useful information on the collection of waste in the study area. The study considered various standard collection technologies and their supporting factors in order to assess the effectiveness of existing methods. The current collection techniques existing in different parts of the country together with unique local factors for these various areas are reported. The findings in many cases reveal that the method of waste collection adopted and equipment used are faced with many challenges. This paper revealed that there is no investment presently made on the existing development plan to initiate a modern waste collection system. The study recommends a new approach that could be used by institutions and government agencies for efficient municipal solid waste collection to achieve sustainable and effective sanitation which will consequently facilitate the development of an aesthetically balanced and friendly environmen

Bioefficiency of Chromolaena odorata (Linn.) on hematological and lipid profiles in sublethal cyanide poisoning in male wistar rats

Chromolaena odorata is an invasive plant which is acclaimed to have cyanide remediation potential from contaminated sites. This examination means to decide the impact of ethanol concentrates of C. odorata (ECO), sodium thiosulphate and a mix of both on hematological parameters and blood lipid profile of rodents presented to potassium cyanide. (KCN). A sum of thirty five male Wistar rats partitioned into seven groups of five units were used. KCN Group rats were administered with KCN alone. Rats in 100ECO, 150ECO, 200ECO groups were administered with 100, 150 and 200 mg/kg body weight of ECO respectively. Rats under Na2sS2O3 and Na2S2O3+ECO groups were administered 200 mg/kg sodium thiosulphate and sodium thiosulphate with ECO at 200 mg/kg respectively. The trial was done in about a month. Toward the finish of the investigation, the packed cell volume (PCV), hemoglobin level (Hb), Red blood cells (RBC) and white blood cells (WBC) were resolved utilizing known biochemical methodology. The outcomes demonstrated a noteworthy increment (p ? 0.05) in PCV, Hb, RBC and WBC level of remedial groups when contrasted with the cyanide group. Total cholesterol (TC), and triglyceride (TG) were altogether lower while HDL-cholesterol was fundamentally expanded in all the treated groups when contrasted and the untreated group given cyanide alone. However, no significant difference in LDL-cholesterol was indicated in all therapeutic groups compared with the cyanide group. The study revealed that C. odorata at the tested doses was able to improve the hematological parameters and lipid profile in cyanide exposed rats

Rough ends of infinite primitive permutation groups

If G is a group of permutations of a set Omega , then the suborbits of G are the orbits of point-stabilisers G_\alpha acting on Omega. The cardinalities of these suborbits are the subdegrees of G. Every infinite primitive permutation group G with finite subdegrees acts faithfully as a group of automorphisms of a locally-finite connected vertex-primitive directed graph Gamma with vertex set Omega, and there is consequently a natural action of G on the ends of Gamma. We show that if G is closed in the permutation topology of pointwise convergence, then the structure of G is determined by the length of any orbit of G acting on the ends of Gamma. Examining the ends of a Cayley graph of a finitely generated group to determine the structure of the group is often fruitful. B. Krön and R. G. Möller have recently generalised the Cayley graph to what they call a rough Cayley graph, and they call the ends of this graph the rough ends of the group. It transpires that the ends of Gamma are the rough ends of G, and so our result is equivalent to saying that the structure of a closed primitive group G whose subdegrees are all finite is determined by the length of any orbit of G on its rough ends

Evaluation of 0 <_ M <_ earthquake data sets in African – Asian region during 1966–2015

Thisarticleevaluatestheoccurrenceof0 r M r 8 earthquakedata setsfortheperiodof50years(thatis,January1,1966toDecember 31,2015)inAfricanandWesternAsiaregion.Itisboundedby latitude40° S to40° N andlongitude30° W to60° E withthefocal depthof0–700km.Seventyseventhousand,sixhundredand ninety-sixdatapointswerepresentedfortheanalysis.Thedata usedwereextractedfromearthquakecatalogofAdvancedNational Seismicsystemvia http://quake.geo.berkeley.edu/cnss/, anofficial websiteoftheNorthernCaliforniaEarthquakeDataCentre,USA. Eachdatumcomprisedtheearthquakeoccurrencedate,timeofthe earthquakeoccurrence,epicenter’s coordinates,focaldepthand magnitude.TheGutenberg-Richter’s relationshipbeingthelongest observedempiricalrelationshipinseismology,analysisofvariance andtimeserieswereusedtoanalyzetheseismicityofthestudy area.Annualdistributionsofearthquakeoccurrencebasedon magnitudevariationswiththelimit0 r M r 8 werepresented. ThetwoconstantsaandbintheGutenberg-Richter’s equation, magnitudeofcompleteness(MC)adjustedR-Squareand F-valuefor theperiodof1966–1975,1976–1985,1986–1995,1996–2005,2006– 2015,andtheentireperiodofinvestigationrangingfrom1966to 2015weredeterminedsoastoinvestigatethevariationsofthese parametersonearthquakeoccurrenceovertime.Thehistogramsof earthquakeoccurrenceagainstmagnitudeofearthquakesforthe selectedyears(1966–1975,1976–1985,1986–1995,1996–2005, 2006–2015,and1966–2015),andthedecadalfrequencydistribu- tionsofearthquakeoccurrencewerealsoplotted.Thefocaldepth occurrenceforeachmagnitudebins(0–0.9,1–1.9,2–2.9,3–3.9,4– 4.9,5–5.9,6–6.9,7–7.9,8–8.9)weregroupedintoshallow,inter- mediate,anddeepdepthsrangingfrom0to70,71to300,and301 to700kmasbeingusedinseismology.Theneuralnetworkanalysis wasalsoappliedtothemagnitudeoftheearthquake.Thenetwork usesatimeseriesmagnitudedataasinputwiththeoutputbeing themagnitudeofthefollowingday.Ifthenatureoftheearthquakes timeseriesisstochastic,modelingandpredictionispossible.The earthquakedatasetspresentedinthisarticlecanfurtherbeadopted in thestudyofseismicitypattern, b-valueusingseriesofmodels, earthquakepredictionandvariationsofearthquakeparameterson Africanand/orArabianplates.Whenthisapproachisintegrated withothertechnique(s),itcanprovideinsightstostabilityof African lithospehricplatesespeciallythecoastalregionofAfrica

An investigation into BIM uptake among contracting firms : an empirical study in Nigeria

Purpose – Building Information Modeling (BIM) is vital in the performance improvement of contracting firms. Thus, there is a need to stimulate its implementation in the construction sector with a view to meeting the competitive demands of the industry. However, there have been very few studies on BIM implementation among contracting firms in Nigeria. Hence, this study examines the current BIM uptake among Nigerian contracting firms, assesses the barriers to BIM implementation, and examines ways of improving BIM implementation within these contracting firms. Design/methodology/approach – A questionnaire survey was conducted on contracting firms (comprising small, medium and large sized firms) in Lagos, Nigeria. The obtained data were analyzed using both descriptive and inferential statistics. These included percentage, mean score, standard deviation, the Kruskal-Wallis test and factor analysis. Findings – The study revealed the current state of BIM implementation among contracting firms in Nigeria in terms of their knowledge of BIM, their usage of BIM as well as the BIM software adopted. Furthermore, the study identified 25 barriers to BIM implementation in contracting firms and identified 15 ways to improve BIM implementation in contracting firms. The relative importance of both the identified barriers and the ways for improving BIM implementation was gauged among contracting firms comprising small, medium and large sized firms. The result of the Kruskal-Wallis test revealed that, except for two (out of 25) identified barriers, and one (out of 15) identified ways of improving BIM implementation in contracting firms, there is no significant statistical difference in the perceptions of the three respondents’ groups. The result of the factor analysis categorized the identified 25 barriers into seven main factors. Practical implications – The study provides empirical evidence on the barriers to BIM implementation and the ways of improving its implementation among contracting firms; thereby providing a better insight of the Nigerian construction industry’s BIM environment. Originality/value – The study’s findings can positively inform the decisions of construction stakeholders to formulate strategies capable of improving BIM implementation in the construction industry at large

Librarians’ attitude toward monetary and non-monetary incentives in university libraries: A case of selected university libraries in Nigeria

The study uses a structured questionnaire to gather information on librarians’ perception towards monetary andnon-monetary incentives in university libraries in Nigeria. Questionnaires were distributed to 45 librarians in the selecteduniversity libraries through the use of simple random sampling techniques to understand the attitude of librarians towardsmonetary and non-monetary incentives. The findings revealed that librarians are aware of both monetary and non-monetaryincentives and that majority of the librarians benefited from monetary incentives. Motivation, job satisfaction and increase inorganizational commitment are some of the benefits librarians derive from monetary and non-monetary incentives.Recommendations include linking of reward directly to performance and the need to pay reasonable salary and wages tolibrarians in order to make them more effective

Integrating statistical machine learning in a semantic sensor web for proactive monitoring and control

Proactive monitoring and control of our natural and built environments is important in various application scenarios. Semantic Sensor Web technologies have been well researched and used for environmental monitoring applications to expose sensor data for analysis in order to provide responsive actions in situations of interest. While these applications provide quick response to situations, to minimize their unwanted effects, research efforts are still necessary to provide techniques that can anticipate the future to support proactive control, such that unwanted situations can be averted altogether. This study integrates a statistical machine learning based predictive model in a Semantic Sensor Web using stream reasoning. The approach is evaluated in an indoor air quality monitoring case study. A sliding window approach that employs the Multilayer Perceptron model to predict short term PM2.5 pollution situations is integrated into the proactive monitoring and control framework. Results show that the proposed approach can effectively predict short term PM2.5 pollution situations: precision of up to 0.86 and sensitivity of up to 0.85 is achieved over half hour prediction horizons, making it possible for the system to warn occupants or even to autonomously avert the predicted pollution situations within the context of Semantic Sensor Web

Awareness and knowledge of mother-to-child transmission of HIV among mothers attending the pediatric HIV clinic, Kano, Nigeria

Background: Nigeria accounts for about 10% of all HIV/AIDS cases in the world. Globally women constitute 48% of adults infected with HIV; in Nigeria, they constitute 57%. There is an increase in the number of children infected with HIV in recent years as the number of HIV-positive women has increased. However, more than 90% of HIV infections in children aged less than 15 years are due to mother-to-child transmission of HIV. Objective: To evaluate the awareness and knowledge of mother-to-child transmission of HIV, HIV/AIDS and the methods to prevent mother-to-child transmission of HIV. Methods: This is a descriptive study. The study was carried out at the pediatric HIV clinic of Aminu Kano Teaching Hospital from 1 st July 2006 to 30 th December 2006. Mothers included in the study were mothers in first contact with HIV facilities, which was at our center, before any form of counseling. The instrument used was a questionnaire designed to assess awareness of the mothers about HIV/AIDS, evaluate their knowledge of possible routes of transmission and measures to prevent vertical transmission. The questionnaire was then pre-tested for comprehensibility, appropriateness of language, sensitivity of questions and average duration of administration. Results: A total of 164 mothers brought their children for treatment to the pediatric HIV clinic. The level of awareness about HIV/AIDS among mothers was very high (100%), and the main sources of information were radio (48.8%) and television (37.8%). Ninety-one percent of mothers were aware of mother-to-child transmission of HIV. Transplacental route (41%) was the commonly identified route of transmission. The level of knowledge and perceptions of mother-to-child transmission of HIV is inadequate. Conclusion: There is a need to scale up education about mother-to-child transmission of HIV in our health facilities