Does Order Negotiation Improve The Job-Shop Workload Control?

Work flows in a job-shop are determined not only by the release load and the time between release factors, but also by the number of accepted orders. There has been extensive research on workload and input-output control aiming at improving the performance of manufacturing operations in job-shops. This paper explores the idea of controlling the workload since the acceptance/rejection of orders stage. A new acceptance/rejection rule is proposed, and tests are conducted to study the sensitivity of job-shop performance to different order acceptance parameters, like the tolerance of the workload limit and the due date extension acceptance. It also evaluates the effect of the negotiation phase of the proposed acceptance rule on the job-shop performance using a simulation model of a generic random job-shop. The extensive simulation experiments allow us to conclude that having a negotiation phase prior to rejection improves almost all workload performance measures. We also conclude that different tolerances of the workload limit affect slightly the performance of the job-shop.job shop, order negotiation, workload control

CHEMICAL COMPOSITION, ANTIOXIDANT AND ANTIMICROBIAL PROPERTIES OF THREE ESSENTIAL OILS FROM PORTUGUESE FLORA

The present work reports on the evaluation of chemical composition and antioxidant and antimicrobial activities of essential oils of three aromatic herbs, growing wild in the south of Portugal, used in traditional food preparations: Foeniculum vulgare, Mentha spicata and Rosmarinus officinalis. The principal components of essential oils were anethole (41.2%) for F. vulgare, carvone (41.1%) for M. spicata and myrcene (23.7%) for R. officinalis. Essential oils showed antioxidant activity either by DPPH radical scavenging method and system β- carotene/acid linoleic method. Antimicrobial activity of essential oils was observed against pathogenic bacteria and yeasts and food spoilage fungi. F.vulgare essential oil showed bacterial activity against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella enteritidis, Staphylococcus aureus, Aspergillus niger and Fusarium oxysporum with MICs of 0.25-0.75mg/mL. M. spicata oil was active against E.coli, S.aureus, C.albicans, A. niger and F. oxysporum with MICs ranging between 0.25 and 0.75mg/mL. R. officinalis essential oil showed activity against E.coli and C.albicans with MICs of 0.5-1.0mg/mL. Having in account the important antioxidant and antimicrobial properties observed in present work, we consider that these essential oils might be useful on pharmaceutical and food industry as natural antibiotic and food preservativ

Selecção de suportes para um consórcio de microorganismos nitrificantes autotróficos

A remoção de compostos de azoto de águas e efluentes é geralmente efectuada por processes biológicos. Dado que as bactérias nitrificantes autotróficas têm taxas de crescimento muito baixas, uma forma de evitar o "wash-out" destes microorganismos num reactor biológico e proceder a sua imobilização. Neste estudo foram utilizados diferentes materiais com vista a seleção dos mais adequados para servirem de suporte a um consórcio de bactérias nitrificantes. Os materiais utilizados foram, por ordem crescente de hidrofobicidade: vidro, polipropileno, polimetilmetacrilato, poliestireno e polietileno (ambos de alta densidade). A quantificação da adesão foi efectuada por pesagem, complementada com observação ao• microscópio electrónico de varrimento e testes de actividade. Os resultados obtidos mostram que qualquer um dos dois géneros de bactérias responsáveis pela nitrificação (Nitrosomonas e Nitrobacter) aderem aos suportes. Verificou-se, também, que a formação de maior quantidade de biofilme não corresponde a maior actividade, o que poderá ser devido a sua estrutura

From Negligence to Populism: An Analysis of Mozambique’s Agricultural Political Economy

The paper analyses the changing configuration of the political system since the Rome Peace Agreement of 1992. It discusses how the “political settlement” underlying the Peace Agreement and the outcomes of multiparty elections thereafter have shaped governance, including policy-making concerning the agriculture sector and the rural economy. The paper argues that private interests and electoral objectives have been important drivers of policy decisions taken by the governing elites concerning the agriculture sector and local governance, with precedence over donor influence. By contrasting the political choices and governance approaches adopted by the two different presidential administrations in office since the first multiparty elections were held in 1994, it is argued that one (led by Joaquim Chissano) is marked by features of “neopatrimonialism”, whereas the other (led by Armando Guebuza) is showing signs of electoral “populism”. The former is characterised by significant rent distribution by the governing elite to a narrow “selectorate”. The latter is manifested by a paternalistic and politically mobilising discourse emanating directly from the President and appealing to the broader electorate, particularly the rural population of the central and Northern region of the country, who has been traditionally opposed to the ruling partyDfI

Outcomes Of Regulatory Change In Urban Mobility: Adjusting Institutions And Governance

Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

Anaerobic co-digestion of coffee waste and sewage sludge

The feasibility of the anaerobic co-digestion of coffee solid waste and sewage sludge was assessed. Five different solid wastes with different chemical properties were studied in mesophilic batch assays, providing basic data on the methane production, reduction of total and volatile solids and hydrolysis rate constant. Most of the wastes had a methane yield of 0.24–0.28 m³CH4(STP)/kg VSinitial and 76–89% of the theoretical methane yield was achieved. Reduction of 50–73% in total solids and 75–80% in volatile solids were obtained and the hydrolysis rate constants were in the range of 0.035–0.063 dֿ¹. One of the solid wastes, composed of 100% barley, achieved a methane yield of 0.02 m³ CH4(STP)/kg VSinitial, reductions of 31% in total solids, 40% in volatile solids and achieved only 11% of the theoretical methane yield. However, this waste presented the highest hydrolysis rate constant. Considering all the wastes, an inverse linear correlation was obtained between methane yield and the hydrolysis rate constant, suggesting that hydrolysis was not the limiting factor in the anaerobic biodegradability of this type of waste.Fundação para a Ciência e a Tecnologia (FCT

Co-digestion of cow manure, food waste and intermittent input of fat

Pulses of oil were added to completely mixed reactors fed with dairy cow manure and food waste, after achieving a stable performance at an organic loading rate of 4.6 ± 0.1 gCOD/(lreactor day), an oily waste effluent from a canned fish processing industry was fed in the form of pulses. The oil concentration rose up to 9, 12, 15 and 18 gCODoil/lreactor, after the pulse feeding in the reactor. The highest fat concentration of 18 gCODoil/lreactor promoted a persistent inhibition in the process of the continuous reactor, although in batch assays, the reactor content evidenced a capacity to degrade more oil and to degrade the accumulated organic matter. All the other pulses had a positive effect in the methane production. From a practical point of view, this work demonstrates that controlled intermittent inputs of oil can enhance the methane production in a co-digestion of cow manure and food waste.Fundo Social Europeu (FSE) - SFRH/BD/18174/2004Fundação para a Ciência e Tecnologia (FCT)

Effect of LCFA content in the co-digestion of manure and food waste

The influence of the lipid content in the mesophilic co-digestion of food waste with cow manure was evaluated. An oily waste was used to simulate the lipid content of food waste. Four reactors with four different concentrations of fat were run in parallel. An oily effluent was added in pulses to simulate different fat contents. The control reactor R1 received no additional fat and R2, R3 and R4 received an increasing input of oil on days 49, 56 and 84 which corresponded to 6, 25 and 36% of Fat COD/total COD in R2, 9, 38 and 46% Fat COD/total COD in R3 and 13, 51 and 55% Fat COD/total COD in R4. The performance was evaluated through the measurement of methane production, effluent soluble chemical oxygen demand (COD), effluent volatile fatty acids, long chain fatty acids (LCFA), total and volatile solids removal. Using single factor analysis of variances (ANOVA) no statistical differences were detected in the reactors performance, in terms of pulse response. The exception was the LCFA adsorbed onto the solid matrix. Hence, R1 only presents palmitic acid (C16:0) adsorbed onto the solid matrix and R2, R3 and R4 presents C16:0 along with stearic (C18:0). The values detected of these two acids were always lower than 25 gCOD/kgTS and no other significant differences were found between the four reactors performance. The added fat was in this case, apparently retained in the reactor in the form of floating yellowish aggregates. The results indicate that cow manure presents a good buffer capacity to overcome the different lipids input of the FW.Fundação para a Ciência e Tecnologia (FCT) - SFRH/BD/18174/2004.Fundo Social Europeu (FSE