No-wait flow shops with makespan minimization are classified as NP-hard. In this paper, the optimization objective is equivalently transformed to total idle-time minimization. The independence relationship between tas...No-wait flow shops with makespan minimization are classified as NP-hard. In this paper, the optimization objective is equivalently transformed to total idle-time minimization. The independence relationship between tasks is analyzed, and objective increment properties are established for the fundamental operators of the heuristics. The quality of the new schedules generated during a heuristic is judged only by objective increments and not by the traditional method, which computes and compares the objective of a whole schedule. Based on objective increments, the time complexity of the heuristic can be decreased by one order. A seed phase is presented to generate an initial solution according to the transformed objective. Construction and improvement phases are introduced by experimental analysis. The FCH （fast composite heuristic） is proposed and compared with the most effective algorithms currently available for the considered problem. Experimental results show that the effectiveness of the FCH is similar to that of the best methods but requires far less computation time. The FCH can also be efficient in real time scheduling and rescheduling for no-wait flow shops.展开更多
Many researches discussing reduced energy consumption for environmental protection focus on machine efficiency or process redesign. To optimize the machine operation time can also save the energy, and these researches...Many researches discussing reduced energy consumption for environmental protection focus on machine efficiency or process redesign. To optimize the machine operation time can also save the energy, and these researches have received great interests in recent years. This study considers three different states of machines, among processing there are two different speeds, to solve the problem of minimizing energy costs under time-of-use tariff with no tardy jobs in flexible flow shop. This problem is basically NP-hard, we proposed a hybrid genetic algorithm (GA) to solve problems in reasonable timeliness. The result shows that to optimize different states of machines under time-of use tariff can reduce energy costs significantly in on-time delivery.展开更多
In this paper the scheduling problem to minimize the expected makespan is discussed on two-machine flow shops with random disturbance on job processing times. The problem is represented by a stochastic programming mod...In this paper the scheduling problem to minimize the expected makespan is discussed on two-machine flow shops with random disturbance on job processing times. The problem is represented by a stochastic programming model. We approximate the stochastic problem by a deterministic problem which can be solved by Johnson's rule. The estimation of approximation error is also discussed by analyzing the stochastic model and its approximate LP model.展开更多
Objective:To assess the food safety knowledge and practices in meat handling,and to determine microbial load and pathogenic organisms in meat at Mekelle city.Methods:A descriptive survey design was used to answer ques...Objective:To assess the food safety knowledge and practices in meat handling,and to determine microbial load and pathogenic organisms in meat at Mekelle city.Methods:A descriptive survey design was used to answer questions concerning the current status of food hygiene and sanitation practiced in the abattoir and butcher shops.Workers from the abattoir and butcher shops were interviewed through a structured questionnaire to assess their food safety knowledge.Bacterial load was assessed by serial dilution method and the major bacterial pathogens were isolated by using standard procedures.Results:15.1%of the abattoir workers had no health certificate and there was no hot water,sterilizer and cooling facility in the abattoir.11.3%of the butchers didn’t use protective clothes.There was a food safety knowledge gap within the abattoir and butcher shop workers.The mean values of bacterial load of abattoir meat,butcher shops and street meat sale was found to be 1.1×10~5,5.6×10~5and 4.3×10~6 cfu/g,respectively.The major bacterial pathogens isolated were Escherichia coli,Staphylococcus aureus and Bacillus cereus.Conclusions:The study revealed that there is a reasonable gap on food safely knowledge by abattoir and butcher shop workers.The microbial profile was also higher compared to standards set by World Health Organization.Due attention should be given by the government to improve the food safety knowledge and the quality standard of meat sold in the city.展开更多
The rent of shops in commercial complex reflects consumers’ preferences to some extent, and provides references for urban planning and the construction and operation of commercial complex. In this paper, Sea World Co...The rent of shops in commercial complex reflects consumers’ preferences to some extent, and provides references for urban planning and the construction and operation of commercial complex. In this paper, Sea World Commercial Complex in Nanshan District of Shenzhen City is taken as the research object, and correlation and variability analysis on 41 groups of shop data are conducted. It is found that rent of shops in the same commercial complex is affected by location, visibility and area of outdoor stall, while the influence of shop area on rent is not obvious. Additionally, there is no significant correlation between the accessibility to traffic stations and the rent of shops in pedestrian business district.展开更多
Do you enjoy art?Maybe you like to draw or color.If you want to do those things,you need supplies.You can go to an art store to buy them.You can buy colored pencils,markers or crayons.You can buy paper to draw picture...Do you enjoy art?Maybe you like to draw or color.If you want to do those things,you need supplies.You can go to an art store to buy them.You can buy colored pencils,markers or crayons.You can buy paper to draw pictures on.You can also buy coloring books.If you want to make things out of paper,you can buy colorful paper,too.Are you a painter?You can buy many different kinds of paint at an art store.展开更多
Thought you couldn't get a half decent cup of joe in this city?Think again-young entrepreneurs in Shanghai are shaping up to be 8 generation of caffeine connoisseurs,leading to a spark of independent coffee shops ...Thought you couldn't get a half decent cup of joe in this city?Think again-young entrepreneurs in Shanghai are shaping up to be 8 generation of caffeine connoisseurs,leading to a spark of independent coffee shops that are the perfect alternative to your daily Starbucks.展开更多
A cross-sectional study was conducted from November 2008 to May 2009 to estimate the prevalence of Salmonella in retail meat shops in Kathmandu. The methods followed were ISO 18593：2004 for swab sample collection, IS...A cross-sectional study was conducted from November 2008 to May 2009 to estimate the prevalence of Salmonella in retail meat shops in Kathmandu. The methods followed were ISO 18593：2004 for swab sample collection, ISO 6579：2002 for Salmonella isolation and manufacturer＇s instructions （SIFIN, Germany） for serotype identification. A questionnaire was used to collect information on some of the risk factors of shops likely to be associated with Salmonella identification. A total of 492 environmental swab samples （164 chopping board samples, 164 knife samples and 164 table samples） from 82 retail meat shops were analyzed. The prevalence of Salmonella positive shops was 40.2% （95% CI： 29-51）. The isolation rates of Salmonella from chopping boards （36.0%）, knives （32.9%） and tables （25.0%） were not significantly different （P 〉 0.05）. Retail meat shops were 1.9 times more likely to yield Salmonella in the evening （38.2%） as compared to the morning （24.4%） （P = 0.001）. S. Typhimurium （54.5%） was the most common serotype found in retail meat shops followed by S. Enteritidis （16.9%）, S. Haifa （13.6%）, S. Virchow （10.4%）, S. Agona （3.9%） and S. enterica （0.6%）. Among the risk factors examined, ＂hygiene status of shop＂, ＂type of shops＂, ＂number of person handling meats＂, ＂number of knives used＂, ＂number of kinds of meat sold＂ and ＂number of kinds of meat sold using different numbers of knives＂ were individually significantly （P 〈 0.05） associated with Salmonella contamination in the retail meat shops. After univariate analysis of these risk factors, a final logistic regression model with Salmonella yes or no category of shops as outcome variable identified four significant predictors. Odds ratios, indicating the likelihood increase of a shop to achieve Salmonella positivity status were 10.17 for multiple persons rather than a single person involved, 7.66 for open rather than closed shops, 9.44 for use of several knives rath展开更多
基金the National Natural Science Foundation of China (Grant Nos.60504029 and 60672092)the National High Technology Re-search and Development Program of China (863 Program) (Grant No.2008AA04Z103)
文摘No-wait flow shops with makespan minimization are classified as NP-hard. In this paper, the optimization objective is equivalently transformed to total idle-time minimization. The independence relationship between tasks is analyzed, and objective increment properties are established for the fundamental operators of the heuristics. The quality of the new schedules generated during a heuristic is judged only by objective increments and not by the traditional method, which computes and compares the objective of a whole schedule. Based on objective increments, the time complexity of the heuristic can be decreased by one order. A seed phase is presented to generate an initial solution according to the transformed objective. Construction and improvement phases are introduced by experimental analysis. The FCH （fast composite heuristic） is proposed and compared with the most effective algorithms currently available for the considered problem. Experimental results show that the effectiveness of the FCH is similar to that of the best methods but requires far less computation time. The FCH can also be efficient in real time scheduling and rescheduling for no-wait flow shops.
文摘Many researches discussing reduced energy consumption for environmental protection focus on machine efficiency or process redesign. To optimize the machine operation time can also save the energy, and these researches have received great interests in recent years. This study considers three different states of machines, among processing there are two different speeds, to solve the problem of minimizing energy costs under time-of-use tariff with no tardy jobs in flexible flow shop. This problem is basically NP-hard, we proposed a hybrid genetic algorithm (GA) to solve problems in reasonable timeliness. The result shows that to optimize different states of machines under time-of use tariff can reduce energy costs significantly in on-time delivery.
文摘In this paper the scheduling problem to minimize the expected makespan is discussed on two-machine flow shops with random disturbance on job processing times. The problem is represented by a stochastic programming model. We approximate the stochastic problem by a deterministic problem which can be solved by Johnson's rule. The estimation of approximation error is also discussed by analyzing the stochastic model and its approximate LP model.
基金Supported by the Tigray Regional National State,Science and Technology Agency(Grant No.TSTA/08/2010)
文摘Objective:To assess the food safety knowledge and practices in meat handling,and to determine microbial load and pathogenic organisms in meat at Mekelle city.Methods:A descriptive survey design was used to answer questions concerning the current status of food hygiene and sanitation practiced in the abattoir and butcher shops.Workers from the abattoir and butcher shops were interviewed through a structured questionnaire to assess their food safety knowledge.Bacterial load was assessed by serial dilution method and the major bacterial pathogens were isolated by using standard procedures.Results:15.1%of the abattoir workers had no health certificate and there was no hot water,sterilizer and cooling facility in the abattoir.11.3%of the butchers didn’t use protective clothes.There was a food safety knowledge gap within the abattoir and butcher shop workers.The mean values of bacterial load of abattoir meat,butcher shops and street meat sale was found to be 1.1×10~5,5.6×10~5and 4.3×10~6 cfu/g,respectively.The major bacterial pathogens isolated were Escherichia coli,Staphylococcus aureus and Bacillus cereus.Conclusions:The study revealed that there is a reasonable gap on food safely knowledge by abattoir and butcher shop workers.The microbial profile was also higher compared to standards set by World Health Organization.Due attention should be given by the government to improve the food safety knowledge and the quality standard of meat sold in the city.
文摘The rent of shops in commercial complex reflects consumers’ preferences to some extent, and provides references for urban planning and the construction and operation of commercial complex. In this paper, Sea World Commercial Complex in Nanshan District of Shenzhen City is taken as the research object, and correlation and variability analysis on 41 groups of shop data are conducted. It is found that rent of shops in the same commercial complex is affected by location, visibility and area of outdoor stall, while the influence of shop area on rent is not obvious. Additionally, there is no significant correlation between the accessibility to traffic stations and the rent of shops in pedestrian business district.
文摘Do you enjoy art?Maybe you like to draw or color.If you want to do those things,you need supplies.You can go to an art store to buy them.You can buy colored pencils,markers or crayons.You can buy paper to draw pictures on.You can also buy coloring books.If you want to make things out of paper,you can buy colorful paper,too.Are you a painter?You can buy many different kinds of paint at an art store.
文摘Thought you couldn't get a half decent cup of joe in this city?Think again-young entrepreneurs in Shanghai are shaping up to be 8 generation of caffeine connoisseurs,leading to a spark of independent coffee shops that are the perfect alternative to your daily Starbucks.
文摘A cross-sectional study was conducted from November 2008 to May 2009 to estimate the prevalence of Salmonella in retail meat shops in Kathmandu. The methods followed were ISO 18593：2004 for swab sample collection, ISO 6579：2002 for Salmonella isolation and manufacturer＇s instructions （SIFIN, Germany） for serotype identification. A questionnaire was used to collect information on some of the risk factors of shops likely to be associated with Salmonella identification. A total of 492 environmental swab samples （164 chopping board samples, 164 knife samples and 164 table samples） from 82 retail meat shops were analyzed. The prevalence of Salmonella positive shops was 40.2% （95% CI： 29-51）. The isolation rates of Salmonella from chopping boards （36.0%）, knives （32.9%） and tables （25.0%） were not significantly different （P 〉 0.05）. Retail meat shops were 1.9 times more likely to yield Salmonella in the evening （38.2%） as compared to the morning （24.4%） （P = 0.001）. S. Typhimurium （54.5%） was the most common serotype found in retail meat shops followed by S. Enteritidis （16.9%）, S. Haifa （13.6%）, S. Virchow （10.4%）, S. Agona （3.9%） and S. enterica （0.6%）. Among the risk factors examined, ＂hygiene status of shop＂, ＂type of shops＂, ＂number of person handling meats＂, ＂number of knives used＂, ＂number of kinds of meat sold＂ and ＂number of kinds of meat sold using different numbers of knives＂ were individually significantly （P 〈 0.05） associated with Salmonella contamination in the retail meat shops. After univariate analysis of these risk factors, a final logistic regression model with Salmonella yes or no category of shops as outcome variable identified four significant predictors. Odds ratios, indicating the likelihood increase of a shop to achieve Salmonella positivity status were 10.17 for multiple persons rather than a single person involved, 7.66 for open rather than closed shops, 9.44 for use of several knives rath
