Intelligent production is an important development direction in intelligent manufacturing,with intelligent factories playing a crucial role in promoting intelligent production.Flexible job shops,as the main form of in...Intelligent production is an important development direction in intelligent manufacturing,with intelligent factories playing a crucial role in promoting intelligent production.Flexible job shops,as the main form of intelligent factories,constantly face dynamic disturbances during the production process,including machine failures and urgent orders.This paper discusses the basic models and research methods of job shop scheduling,emphasizing the important role of dynamic job shop scheduling and its response schemes in future research.A multi-objective flexible job shop dynamic scheduling mathematical model is established,highlighting its complex and multi-constraint characteristics under different interferences.A classification discussion is conducted on the dynamic response methods and optimization objectives under machine failures,emergency orders,fuzzy completion times,and mixed dynamic events.The development process of traditional scheduling rules and intelligent methods in dynamic scheduling are also analyzed.Finally,based on the current development status of job shop scheduling and the requirements of intelligent manufacturing,the future development trends of dynamic scheduling in flexible job shops are proposed.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
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 rather than one knife and 5.18 for single kind of meat using several knives. The results of this investigation revealed that retail meat shops to a noticeable extent are Salmonella contaminated, with a considerable degree of cross-contamination between meats and personnel and equipment used during a day in processing of meats.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
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
Duty-free shops play a very important role in tourism. In particular, overseas tourist souvenirs are related to the export of domestic products. Foreign tourists' spending on souvenirs is equivalent to buying fore...Duty-free shops play a very important role in tourism. In particular, overseas tourist souvenirs are related to the export of domestic products. Foreign tourists' spending on souvenirs is equivalent to buying foreign currency, so it directly affects the national economy. Duty-free shops are a kind of tourist destination where purchases take place. The products sold cannot flow into the home economy at duty-free prices, so they are treated as exports. This increases the acquisition of foreign currency and helps to improve the balance of payments, thus creating a higher value added than exports, whose importance lies in creation.展开更多
She clambers up a rock, reaches both hands onto comers of the shabby cement wall and heaves herself up, being careful not to catch her school bag on the protruding bricks. She straddles the top and then jumps gingerly...She clambers up a rock, reaches both hands onto comers of the shabby cement wall and heaves herself up, being careful not to catch her school bag on the protruding bricks. She straddles the top and then jumps gingerly down onto the pebbled ground beside the railway line.展开更多
No-wait job-shop scheduling (NWJSS) problem is one of the classical scheduling problems that exist on many kinds of industry with no-wait constraint, such as metal working, plastic, chemical, and food industries. Seve...No-wait job-shop scheduling (NWJSS) problem is one of the classical scheduling problems that exist on many kinds of industry with no-wait constraint, such as metal working, plastic, chemical, and food industries. Several methods have been proposed to solve this problem, both exact (i.e. integer programming) and metaheuristic methods. Cross entropy (CE), as a new metaheuristic, can be an alternative method to solve NWJSS problem. This method has been used in combinatorial optimization, as well as multi-external optimization and rare-event simulation. On these problems, CE implementation results an optimal value with less computational time in average. However, using original CE to solve large scale NWJSS requires high computational time. Considering this shortcoming, this paper proposed a hybrid of cross entropy with genetic algorithm (GA), called CEGA, on m-machines NWJSS. The results are compared with other metaheuritics: Genetic Algorithm-Simulated Annealing (GASA) and hybrid tabu search. The results showed that CEGA providing better or at least equal makespans in comparison with the other two methods.展开更多
Aim of this research is to minimize makespan in the flexible job shop environment by the use of genetic algorithms and scheduling rules. Software is developed using genetic algorithms and scheduling rules based on cer...Aim of this research is to minimize makespan in the flexible job shop environment by the use of genetic algorithms and scheduling rules. Software is developed using genetic algorithms and scheduling rules based on certain constraints such as non-preemption of jobs, recirculation, set up times, non-breakdown of machines etc. Purpose of the software is to develop a schedule for flexible job shop environment, which is a special case of job shop scheduling problem. Scheduling algorithm used in the software is verified and tested by using MT10 as benchmark problem, presented in the flexible job shop environment at the end. LEKIN software results are also compared with results of the developed software by the use of MT10 benchmark problem to show that the latter is a practical software and can be used successfully at BIT Training Workshop.展开更多
A modified shifting bottleneck algorithm was proposed to solve scheduling problems of a large-scale job shop.Firstly,a new structured algorithm was employed for sub-problems so as to reduce the computational burden an...A modified shifting bottleneck algorithm was proposed to solve scheduling problems of a large-scale job shop.Firstly,a new structured algorithm was employed for sub-problems so as to reduce the computational burden and suit for large-scale instances more effectively.The modified cycle avoidance method,incorporating with the disjunctive graph model and topological sort algorithm,was applied to guaranteeing the feasibility of solutions with considering delayed precedence constraints.Finally,simulation experiments were carried out to verify the feasibility and effectiveness of the modified method.The results demonstrate that the proposed algorithm can solve the large-scale job shop scheduling problems(JSSPs) within a reasonable period of time and obtaining satisfactory solutions simultaneously.展开更多
This work addresses bi-objective hybrid flow shop scheduling problems considering consistent sublots(Bi-HFSP_CS).The objectives are to minimize the makespan and total energy consumption.First,the Bi-HFSP_CS is formali...This work addresses bi-objective hybrid flow shop scheduling problems considering consistent sublots(Bi-HFSP_CS).The objectives are to minimize the makespan and total energy consumption.First,the Bi-HFSP_CS is formalized,followed by the establishment of a mathematical model.Second,enhanced version of the artificial bee colony(ABC)algorithms is proposed for tackling the Bi-HFSP_CS.Then,fourteen local search operators are employed to search for better solutions.Two different Q-learning tactics are developed to embed into the ABC algorithm to guide the selection of operators throughout the iteration process.Finally,the proposed tactics are assessed for their efficacy through a comparison of the ABC algorithm,its three variants,and three effective algorithms in resolving 95 instances of 35 different problems.The experimental results and analysis showcase that the enhanced ABC algorithm combined with Q-learning(QABC1)demonstrates as the top performer for solving concerned problems.This study introduces a novel approach to solve the Bi-HFSP_CS and illustrates its efficacy and superior competitive strength,offering beneficial perspectives for exploration and research in relevant domains.展开更多
1 On a Sunday morning,Zheng Shiying drove 130 kilometers to a village on the outskirts of Beijing,not for a hike or a hot spring,but for a cup of coffee.Housed in an old stone building that looks untouched by time,by ...1 On a Sunday morning,Zheng Shiying drove 130 kilometers to a village on the outskirts of Beijing,not for a hike or a hot spring,but for a cup of coffee.Housed in an old stone building that looks untouched by time,by the time Zheng arrived,the caféwas already packed with weekend visitors,and finding a seat was a bit of a challenge.展开更多
Stepping out of Danyang Railway Station,the large sign reading“China Danyang Optical City”immediately comes into view across the road.Inside the bustling marketplace,a dazzling array of eyeglass frames and lenses is...Stepping out of Danyang Railway Station,the large sign reading“China Danyang Optical City”immediately comes into view across the road.Inside the bustling marketplace,a dazzling array of eyeglass frames and lenses is neatly displayed in rows of shops,attracting consumers from across the country.展开更多
You may not expect that the talk shows that frequently dominate the charts today originated from coffee shops in England in the 18th century.The coffee shop was a breeding place for early public discussions,where peop...You may not expect that the talk shows that frequently dominate the charts today originated from coffee shops in England in the 18th century.The coffee shop was a breeding place for early public discussions,where people engaged in free debates on political and social issues.展开更多
III.Solve the problems.(1)Tom and his sister set out on a walk at 2:00.They walked by some shops and through the park.1 hour later,they returned home.What time was it when they got home?
New Policy to Boost Consumption Chinese authorities on 30 October issued a notice regarding improvements to the policies of duty-free shops aimed at boosting consumption.Effective on 1 November,the policies aim to enc...New Policy to Boost Consumption Chinese authorities on 30 October issued a notice regarding improvements to the policies of duty-free shops aimed at boosting consumption.Effective on 1 November,the policies aim to encourage consumers to shop domestically,according to the notice jointly issued by the Ministry of Finance and four other departments.展开更多
基金supported by the National Key Research and Development Program Project(No.2021YFB3301300).
文摘Intelligent production is an important development direction in intelligent manufacturing,with intelligent factories playing a crucial role in promoting intelligent production.Flexible job shops,as the main form of intelligent factories,constantly face dynamic disturbances during the production process,including machine failures and urgent orders.This paper discusses the basic models and research methods of job shop scheduling,emphasizing the important role of dynamic job shop scheduling and its response schemes in future research.A multi-objective flexible job shop dynamic scheduling mathematical model is established,highlighting its complex and multi-constraint characteristics under different interferences.A classification discussion is conducted on the dynamic response methods and optimization objectives under machine failures,emergency orders,fuzzy completion times,and mixed dynamic events.The development process of traditional scheduling rules and intelligent methods in dynamic scheduling are also analyzed.Finally,based on the current development status of job shop scheduling and the requirements of intelligent manufacturing,the future development trends of dynamic scheduling in flexible job shops are proposed.
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 rather than one knife and 5.18 for single kind of meat using several knives. The results of this investigation revealed that retail meat shops to a noticeable extent are Salmonella contaminated, with a considerable degree of cross-contamination between meats and personnel and equipment used during a day in processing of meats.
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.
文摘Duty-free shops play a very important role in tourism. In particular, overseas tourist souvenirs are related to the export of domestic products. Foreign tourists' spending on souvenirs is equivalent to buying foreign currency, so it directly affects the national economy. Duty-free shops are a kind of tourist destination where purchases take place. The products sold cannot flow into the home economy at duty-free prices, so they are treated as exports. This increases the acquisition of foreign currency and helps to improve the balance of payments, thus creating a higher value added than exports, whose importance lies in creation.
文摘She clambers up a rock, reaches both hands onto comers of the shabby cement wall and heaves herself up, being careful not to catch her school bag on the protruding bricks. She straddles the top and then jumps gingerly down onto the pebbled ground beside the railway line.
文摘No-wait job-shop scheduling (NWJSS) problem is one of the classical scheduling problems that exist on many kinds of industry with no-wait constraint, such as metal working, plastic, chemical, and food industries. Several methods have been proposed to solve this problem, both exact (i.e. integer programming) and metaheuristic methods. Cross entropy (CE), as a new metaheuristic, can be an alternative method to solve NWJSS problem. This method has been used in combinatorial optimization, as well as multi-external optimization and rare-event simulation. On these problems, CE implementation results an optimal value with less computational time in average. However, using original CE to solve large scale NWJSS requires high computational time. Considering this shortcoming, this paper proposed a hybrid of cross entropy with genetic algorithm (GA), called CEGA, on m-machines NWJSS. The results are compared with other metaheuritics: Genetic Algorithm-Simulated Annealing (GASA) and hybrid tabu search. The results showed that CEGA providing better or at least equal makespans in comparison with the other two methods.
文摘Aim of this research is to minimize makespan in the flexible job shop environment by the use of genetic algorithms and scheduling rules. Software is developed using genetic algorithms and scheduling rules based on certain constraints such as non-preemption of jobs, recirculation, set up times, non-breakdown of machines etc. Purpose of the software is to develop a schedule for flexible job shop environment, which is a special case of job shop scheduling problem. Scheduling algorithm used in the software is verified and tested by using MT10 as benchmark problem, presented in the flexible job shop environment at the end. LEKIN software results are also compared with results of the developed software by the use of MT10 benchmark problem to show that the latter is a practical software and can be used successfully at BIT Training Workshop.
基金National Natural Science Foundations of China(Nos.71471135,61273035)
文摘A modified shifting bottleneck algorithm was proposed to solve scheduling problems of a large-scale job shop.Firstly,a new structured algorithm was employed for sub-problems so as to reduce the computational burden and suit for large-scale instances more effectively.The modified cycle avoidance method,incorporating with the disjunctive graph model and topological sort algorithm,was applied to guaranteeing the feasibility of solutions with considering delayed precedence constraints.Finally,simulation experiments were carried out to verify the feasibility and effectiveness of the modified method.The results demonstrate that the proposed algorithm can solve the large-scale job shop scheduling problems(JSSPs) within a reasonable period of time and obtaining satisfactory solutions simultaneously.
基金supported by the National Natural Science Foundation of China(No.62173356)Science and Technology Development Fund(FDCT),Macao SAR(No.0019/2021/A)+2 种基金Zhuhai Industry-University-Research Project with Hongkong and Macao(No.ZH22017002210014PWC)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011531)Key Technologies for Scheduling and Optimization of Complex Distributed Manufacturing Systems(No.22JR10KA007).
文摘This work addresses bi-objective hybrid flow shop scheduling problems considering consistent sublots(Bi-HFSP_CS).The objectives are to minimize the makespan and total energy consumption.First,the Bi-HFSP_CS is formalized,followed by the establishment of a mathematical model.Second,enhanced version of the artificial bee colony(ABC)algorithms is proposed for tackling the Bi-HFSP_CS.Then,fourteen local search operators are employed to search for better solutions.Two different Q-learning tactics are developed to embed into the ABC algorithm to guide the selection of operators throughout the iteration process.Finally,the proposed tactics are assessed for their efficacy through a comparison of the ABC algorithm,its three variants,and three effective algorithms in resolving 95 instances of 35 different problems.The experimental results and analysis showcase that the enhanced ABC algorithm combined with Q-learning(QABC1)demonstrates as the top performer for solving concerned problems.This study introduces a novel approach to solve the Bi-HFSP_CS and illustrates its efficacy and superior competitive strength,offering beneficial perspectives for exploration and research in relevant domains.
文摘1 On a Sunday morning,Zheng Shiying drove 130 kilometers to a village on the outskirts of Beijing,not for a hike or a hot spring,but for a cup of coffee.Housed in an old stone building that looks untouched by time,by the time Zheng arrived,the caféwas already packed with weekend visitors,and finding a seat was a bit of a challenge.
文摘Stepping out of Danyang Railway Station,the large sign reading“China Danyang Optical City”immediately comes into view across the road.Inside the bustling marketplace,a dazzling array of eyeglass frames and lenses is neatly displayed in rows of shops,attracting consumers from across the country.
文摘You may not expect that the talk shows that frequently dominate the charts today originated from coffee shops in England in the 18th century.The coffee shop was a breeding place for early public discussions,where people engaged in free debates on political and social issues.
文摘III.Solve the problems.(1)Tom and his sister set out on a walk at 2:00.They walked by some shops and through the park.1 hour later,they returned home.What time was it when they got home?
文摘New Policy to Boost Consumption Chinese authorities on 30 October issued a notice regarding improvements to the policies of duty-free shops aimed at boosting consumption.Effective on 1 November,the policies aim to encourage consumers to shop domestically,according to the notice jointly issued by the Ministry of Finance and four other departments.
