Optimal Time-dependent Sequenced Route Queries in Road Networks

In this paper we present an algorithm for optimal processing of time-dependent sequenced route queries in road networks, i.e., given a road network where the travel time over an edge is time-dependent and a given ordered list of categories of interest, we find the fastest route between an origin and destination that passes through a sequence of points of interest belonging to each of the specified categories of interest. For instance, considering a city road network at a given departure time, one can find the fastest route between one's work and his/her home, passing through a bank, a supermarket and a restaurant, in this order. The main contribution of our work is the consideration of the time dependency of the network, a realistic characteristic of urban road networks, which has not been considered previously when addressing the optimal sequenced route query. Our approach uses the A* search paradigm that is equipped with an admissible heuristic function, thus guaranteed to yield the optimal solution, along with a pruning scheme for further reducing the search space. In order to compare our proposal we extended a previously proposed solution aimed at non-time dependent sequenced route queries, enabling it to deal with the time-dependency. Our experiments using real and synthetic data sets have shown our proposed solution to be up to two orders of magnitude faster than the temporally extended previous solution.Comment: 10 pages, 12 figures To be published as a short paper in the 23rd ACM SIGSPATIA

Aplicação da sequência ultra/nanofiltração para valorização e redução do impacto ambiental de lactossoro de quijo de ovelha

Proceedings of Renaissance of the regions of Southern Europe, University of Évora: july 10-11, 2014.The by‐products of agro‐industries, due to its high content of nutritive substances, in particular proteins and carbohydrates, have been the subject of intense investigation with a view to their recovery/reuse, towards sustainability. One of these by‐products is ovine cheese whey, that is mainly produced in Southern European countries, as a result of the production of ovine cheeses of Protected Designation of Origin. In most cases, that whey is disposed off into public sewage, causing problems in conventional treatment plants, due to its high organic load. In some countries, e.g. Portugal, Spain and Italy, part of the ovine cheese whey is further processed to obtain whey cheeses, designated by different names, such as requeijão, requesón and ricotta. However, not all of these cheese whey can be transformed due to the high volumes generated. Membrane technology has emerged as a significant innovation for recovery and treatment, because it is more economical than other alternatives, require much less land area than competing technologies and may produce water suitable for multiple proposes. In this work, an example of using membrane processes in the recovery of ovine cheese whey is presented. The operations of ultrafiltration (UF) and nanofiltration (NF) of ovine cheese whey were investigated with the objective of producing added‐value products, such as protein concentrates by UF, lactose concentrates by NF and final permeates with a very low organic load. UF experiments were performed with skimmed cheese whey, both in total recirculation and concentration modes. The equipment used was a plate‐and‐frame unit (Lab Unit M20). Ultrafiltration was performed with organic membranes ETNA 10PP with a surface area of 0,072 m2 and a cut‐off of 10 kDa. Ultrafiltration allowed a clear separation between the protein fraction and a fraction rich in lactose and minerals. About 40% of organic matter, expressed as COD was retained. Nanofiltration of UF permeates was done with membranes NFT50 with a membrane surface area of 0,072 m2..This operation allowed a high retention of lactose (98.8%) and the production of a permeate with a very low organic load. The retention of organic matter, in terms of COD was about 93%. The sequence of operations UF/NF allowed to produce two added‐value products, reducing at the same time the organic pollution of the final stream. Nevertheless, the quality of the final water should be assessed, according with the intended use.RESUMO. Os subprodutos das agro‐indústrias, devido ao seu elevado teor em substâncias nutritivas, em particular proteínas e hidratos de carbono, têm sido objecto de uma intensa investigação com objectivos de recuperação/reutilização, tendo em vista um desenvolvimento sustentável. Um destes subprodutos é o soro de queijo de ovelha, produzido principalmente nos países do sul da Europa, como resultado da produção de queijos de ovelha de Denominação de Origem Protegida. Na maioria dos casos, o soro produzido é lançado nos esgotos municipais, causando problemas em estações de tratamento convencionais, devido à sua elevada carga orgânica. Em alguns países, como Portugal, Espanha e Itália, parte do soro é processado para obtenção de queijos de soro, designados por nomes diferentes, como requeijão, requesón e ricota. No entanto, nem todo o soro produzido pode ser transformado, devido aos elevados volumes gerados. As tecnologias de membranas surgiram como uma inovação significativa para a recuperação/tratamento de vários produtos, dado que relativamente a outros processos alternativos, são mais económicas, podendo produzir água de qualidade adequada para diversos fins. Neste trabalho, é apresentado um exemplo de utilização de processos de membrana na recuperação de soro de queijo de ovelha. As operações de ultrafiltração (UF) e nanofiltração (NF) foram investigadas com o objetivo de produzir produtos de valor acrescentado, como concentrados proteicos por UF, concentrados de lactose por NF e permeados finais, com cargas orgânicas baixas. Os ensaios de UF foram realizados com soro desnatado, em recirculação total e em concentração. O equipamento utilizado foi um módulo de pratos planos (Lab Unidade M20). Na ultrafiltração, foram usadas membranas orgânicas ETNA 10PP, de área superficial 0.072 m2 e com um peso molecular de corte de 10 kDa. A ultrafiltração permitiu uma nítida separação entre a fração proteica e uma fração rica em lactose e sais minerais. Cerca de 40% da matéria orgânica, expressa como CQO, foi retida. Na nanofiltração dos permeados da UF utilizaram‐se membranas NFT50, com uma área de superfície de 0.072 m2. Esta operação permitiu uma elevada retenção de lactose (98.8%) e a obtenção de um permeado com uma carga orgânica bastante reduzida. O factor de retenção da matéria orgânica, em termos de CQO, foi cerca de 93%. A sequência de separações UF / NF permitiu produzir dois produtos de valor acrescentado, reduzindo ao mesmo tempo a poluição orgânica da corrente final. No entanto, a qualidade da água final deve ser avaliada, de acordo com o uso pretendido

Evidence of secondary relaxations in the dielectric spectra of ionic liquids

We investigated the dynamics of a series of room temperature ionic liquids based on the same 1-butyl-3-methyl imidazolium cation and different anions by means of broadband dielectric spectroscopy covering 15 decades in frequency (10^(-6)-10^9 Hz), and in the temperature range from 400 K down to 35 K. An ionic conductivity is observed above the glass transition temperature T_{g} with a relaxation in the electric modulus representation. Below T_{g}, two relaxation processes appear, with the same features as the secondary relaxations typically observed in molecular glasses. The activation energy of the secondary processes and their dependence on the anion are different. The slower process shows the characteristics of an intrinsic Johari-Goldstein relaxation, in particular an activation energy E_{beta}=24k_{B}T_{g} is found, as observed in molecular glasses.Comment: Major revision, submitted to Phys. Rev. Let

Microbiological profile in Serra ewes' cheese during ripening

The microflora of Serra cheese was monitored during a 35 d ripening period at three different periods within the ewe's lactation season. After 7 d ripening, the numbers of micro-organisms reached their maximum, and lactic acid bacteria (LAB) and coliforms were the predominant groups. Pseudomonads were not detected after 1 week of ripening. At all stages of ripening, cheeses manufactured in spring exhibited the lowest numbers of LAB and yeasts, whereas cheeses manufactured in winter showed the lowest numbers of coliforms and staphylococci. Leuconostoc lactis was the most abundant LAB found in Serra cheese whereas Enterococcus faecium and Lactococcus lactis spp. lactis exhibited the highest decrease in percentage composition. Numbers of both Leuc. mesenteroides and Lactobacillus paracasei tended to increase throughout ripening. The most abundant coliform was Hafnia alvei. Klebsiella oxytoca was found in curd but declined in number during ripening. Staphylococcal flora of curd was mainly composed of Staphylococcus xylosus, Staph. aureus and Staph. epidermidis. Staphylococcus xylosus was the major species found at the end of ripening. Pseudomonas fluorescens, was the only Pseudomonas species isolated from the curd. Although a broad spectrum of yeasts were found in Serra cheese, Sporobolomyces roseus was the most abundant yeast isolated