Recent investigations have shown that with varying the amplitude of the external force, the deterministic ratchets exhibit multiple current reversals, which are undesirable in certain circumstances. To control the mul...Recent investigations have shown that with varying the amplitude of the external force, the deterministic ratchets exhibit multiple current reversals, which are undesirable in certain circumstances. To control the multiple reverse current to unidirectional current, an adaptive control law is presented inspired from the relation between multiple reversaJs current and the chaos-periodic/quasiperiodic transition of the transport velocity. The designed controller can stabilize the transport velocity of ratchets to steady state and suppress any chaos-periodic/quasiperiodic transition, namely, the stable transport in ratchets is achieved, which makes the current sign unchanged.展开更多
This paper highlighted the losses occurring along the wheat supply chain in Rio Grande do Sul （RS）, Brazil, which accounts for almost half of the domestic wheat production. Based on a field research, a questionnaire...This paper highlighted the losses occurring along the wheat supply chain in Rio Grande do Sul （RS）, Brazil, which accounts for almost half of the domestic wheat production. Based on a field research, a questionnaire was applied to representative agents in the market. Then the wheat supply chain in the state of RS was characterized and loss rates in each stage of that chain were quantified. Typically, losses during transportation in the domestic market account for about 11.8% of the total amount of wheat grain that leaves the farms. Losses during harvest and storage in cooperatives, which account for 93.2% of total losses, stand out in this context. Transportation operations account for 6.8% of total losses in the analyzed flow. Based on the results obtained in this study, strategies are suggested to reduce food losses in different links of the logistics chain, such as to evidence and quantify the wheat losses, to manage losses and set reduction targets and to give attention to transportation service levels.展开更多
The analysis of spatial mismatches in access to employment remains a very important area of labour market literature. A particular case is that of the mismatches in urban labor markets, which can result in substantial...The analysis of spatial mismatches in access to employment remains a very important area of labour market literature. A particular case is that of the mismatches in urban labor markets, which can result in substantial differences in the employment opportunities available in city centre and suburbs. This study examines the spatial mismatches present in the labour market of Santa Cruz de Tenerife. To that end, the results of a survey taken in 2003-2004 with a sample of 2000 city residents were reviewed. Results confirm the importance of transport policy for city residents; they suggest that public transport linking the different districts to the city centre should be reviewed.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10862001 and 10947011the Construction of Key Laboratories in Universities of Guangxi under Grant No. 200912
文摘Recent investigations have shown that with varying the amplitude of the external force, the deterministic ratchets exhibit multiple current reversals, which are undesirable in certain circumstances. To control the multiple reverse current to unidirectional current, an adaptive control law is presented inspired from the relation between multiple reversaJs current and the chaos-periodic/quasiperiodic transition of the transport velocity. The designed controller can stabilize the transport velocity of ratchets to steady state and suppress any chaos-periodic/quasiperiodic transition, namely, the stable transport in ratchets is achieved, which makes the current sign unchanged.
文摘This paper highlighted the losses occurring along the wheat supply chain in Rio Grande do Sul （RS）, Brazil, which accounts for almost half of the domestic wheat production. Based on a field research, a questionnaire was applied to representative agents in the market. Then the wheat supply chain in the state of RS was characterized and loss rates in each stage of that chain were quantified. Typically, losses during transportation in the domestic market account for about 11.8% of the total amount of wheat grain that leaves the farms. Losses during harvest and storage in cooperatives, which account for 93.2% of total losses, stand out in this context. Transportation operations account for 6.8% of total losses in the analyzed flow. Based on the results obtained in this study, strategies are suggested to reduce food losses in different links of the logistics chain, such as to evidence and quantify the wheat losses, to manage losses and set reduction targets and to give attention to transportation service levels.
文摘The analysis of spatial mismatches in access to employment remains a very important area of labour market literature. A particular case is that of the mismatches in urban labor markets, which can result in substantial differences in the employment opportunities available in city centre and suburbs. This study examines the spatial mismatches present in the labour market of Santa Cruz de Tenerife. To that end, the results of a survey taken in 2003-2004 with a sample of 2000 city residents were reviewed. Results confirm the importance of transport policy for city residents; they suggest that public transport linking the different districts to the city centre should be reviewed.
