Service scheduling in garden maintenance

Neoturf is a Portuguese company working in the area of project, building and garden’s maintenance. Neoturf would like to have a procedure for scheduling and routing efficiently the clients from garden maintenance services. The company has two teams available during the whole year and an additional team during summer to handle all the maintenance jobs. Each team consists of two or three employees with a vehicle fully equipped with the tools that allow to carry out every kind of maintenance service. In the beginning of each year, the number and frequency of maintenance interventions to conduct during the year, on each client, are accorded. Each client is assigned to the same team and, usually, time windows are established so that visits to the client should occur only within these periods. As the Neoturf costumers’ are geographically spread over a wide region, the total distance on visiting clients is a factor that has a heavy weight on the costs of the company. Neoturf is concerned with reducing these costs, while satisfying the agreements with the clients

Report on "Scheduling in a factory"

In order to carry out their orders of shoe soles, this company has a number of tasks T_1, ..., T_n of different lengths to be assigned to groups of machines. Each group is operated by one worker (two in one case), and an operation cycle corresponds to injection, cooling, and removal of the sole. The time taken at each step varies from one order to another, and when starting a new task a machine needs to be tuned, which takes some extra time. Machines are working in parallel. At the moment the assignment is carried out empirically, and the problem proposed is to optimize the procedure

Asymmetry to symmetry transition of Fano line-shape: Analytical derivation

An analytical derivation of Fano line-shape asymmetry ratio has been presented here for a general case. It is shown that Fano line-shape becomes less asymmetric as \q is increased and finally becomes completely symmetric in the limiting condition of q equal to infinity. Asymmetry ratios of Fano line-shapes have been calculated and are found to be in good consonance with the reported expressions for asymmetry ratio as a function of Fano parameter. Application of this derivation is also mentioned for explanation of asymmetry to symmetry transition of Fano line-shape in quantum confined silicon nanostructures.Comment: 3 figures, Latex files, Theoretica

A Routing/Assignment Problem in Garden Maintenance Services

We address a routing/assignment problem posed by Neoturf, which is a Portuguese company working in the area of project, building and garden’s main- tenance. The aim is to define a procedure for scheduling and routing efficiently its clients of garden maintenance services. The company has two teams available throughout the year to handle all the maintenance jobs. Each team consists of two or three employees with a fully-equipped vehicle capable of carrying out every kind of maintenance service. At the beginning of each year, the number and frequency of maintenance interventions to conduct during the year, for each client, are agreed. Time windows are established so that visits to the client should occur only within these periods. There are clients that are supposed to be always served by the same team, but other clients can be served indifferently by any of the two teams. Since clients are geographically spread over a wide region, the total distance traveled while visiting clients is a factor that weighs heavily on the company costs. Neoturf is con- cerned with reducing these costs, while satisfying agreements with its clients. We give a mixed integer linear programming formulation for the problem, discuss lim- itations on the size of instances that can be solved to guarantee optimality, present a modification of the Clarke and Wright heuristic for the vehicle routing with time windows, and report preliminary computational results obtained with Neoturf data.info:eu-repo/semantics/publishedVersio

Effective Fokker-Planck Equation for Birhythmic Modified van der Pol Oscillator

We present an explicit solution based on the phase-amplitude approximation of the Fokker-Planck equation associated with the Langevin equation of the birhythmic modified van der Pol system. The solution enables us to derive probability distributions analytically as well as the activation energies associated to switching between the coexisting different attractors that characterize the birhythmic system. Comparing analytical and numerical results we find good agreement when the frequencies of both attractors are equal, while the predictions of the analytic estimates deteriorate when the two frequencies depart. Under the effect of noise the two states that characterize the birhythmic system can merge, inasmuch as the parameter plane of the birhythmic solutions is found to shrink when the noise intensity increases. The solution of the Fokker-Planck equation shows that in the birhythmic region, the two attractors are characterized by very different probabilities of finding the system in such a state. The probability becomes comparable only for a narrow range of the control parameters, thus the two limit cycles have properties in close analogy with the thermodynamic phases

Quality improvement of a white and a red wine with less sulphur dioxide by the addition of a mixture of glutathione, caffeic acid and gallic acid

The effect of a mixture of glutathione, caffeic acid and gallic acid, at 20 mg/L, 60 mg/L and 20 mg/L respectively, on the quality of a white and a red wine with less than the typical SO2 was studied. The mixture was added in Vinho Verde white wine containing 20 mg/L free SO2 at bottling. Wine quality was evaluated in comparison with wine with 20 mg/L and control wine with typical (35 mg/L) free SO2. By the storage time, wine in which the mixture was added appeared to be of better quality than that with 20 mg/L free SO2. It exhibited higher scores in sensory attributes and lower degree of oxidation as indicated by the chromatic characteristics L*, b* and C*. Wine with typical SO2 exhibited higher scores in sensory analysis than the others. The same mixture was also added into a Merlot-Cabernet Sauvignon blend red wine at bottling. Wine quality was evaluated during storage in comparison with wine with 25 mg/L and control wine with typical (35 mg/L) free SO2. By the storage time, wine in which the mixture was added appeared to be of better sensory quality than that with 25 mg/L free SO2. Moreover, it exhibited higher concentrations of some aroma esters compared to wine with less SO2, similar to those of wine with typical SO2, as determined by SPME/GC-MS analysis. Wine with typical SO2 exhibited better aroma than the others

Efficient edge domination in regular graphs

An induced matching of a graph G is a matching having no two edges joined by an edge. An efficient edge dominating set of G is an induced matching M such that every other edge of G is adjacent to some edge in M. We relate maximum induced matchings and efficient edge dominating sets, showing that efficient edge dominating sets are maximum induced matchings, and that maximum induced matchings on regular graphs with efficient edge dominating sets are efficient edge dominating sets. A necessary condition for the existence of efficient edge dominating sets in terms of spectra of graphs is established. We also prove that, for arbitrary fixed p 3, deciding on the existence of efficient edge dominating sets on p-regular graphs is NP-complet

Personal exposure to particle concentration in a busy street

info:eu-repo/semantics/publishedVersio