Operations management is essential for gaining competitiveness in most manufacturing or service-offering organizations.Therefore,this report is going to analyze the way in which effective operations managers use proce...Operations management is essential for gaining competitiveness in most manufacturing or service-offering organizations.Therefore,this report is going to analyze the way in which effective operations managers use process strategy as a competitive weapon.Besides,based on relevant theories,a case of fast food production process will be studied.展开更多
Background： The quantitative impact of forest management on forests＇ wood resource was evaluated for Picea and Fagus mixed forests. The effects on the productivity of tendering operations, thinnings and rotation len...Background： The quantitative impact of forest management on forests＇ wood resource was evaluated for Picea and Fagus mixed forests. The effects on the productivity of tendering operations, thinnings and rotation length have seldom been directly quantified on landscape scale. Methods： Two sites of similar fertility but subject to contrasted forest management were studied with detailed inventories： one in Germany, the other in Romania, and compared with the respective national forest inventories. In Romania, regulations impose very long rotations, low thinnings and a period of no-cut before harvest. In contrast, tending and thinnings are frequent and intense in Germany. Harvests start much earlier and must avoid clear cutting but maintain a permanent forest cover with natural regeneration. While Germany has an average annual wood increment representative for Central Europe, Romania represents the average for Eastern Europe. Results： The lack of tending and thinning in the Romanian site resulted in twice as many trees per hectare as in the German site for the same age. The productivity in Romanian production forests was 20 % lower than in Germany despite a similar fertility. The results were supported by the data from the national forest inventory of each country, which confirmed that the same differential exists at country scale. Furthermore, provided the difference in rotation length, two crops are harvested in Germany when only one is harvested in Romania. The losses of production due to a lower level of management in Romania where estimated to reach 12.8 million m3.y-1 in regular mountain production forests, and to 15 million m3.y-1 if managed protection forest is included. Conclusions： The productivity of Picea and Fagus mountain forests in Romania is severely depressed by the lack of tending and thinning, by overly long rotations and the existence of a 25-years no-cut period prior to harvest. The average standing volume in Germany was 50 % lower than in Romania, but the higher harvesting rate resulted in more than doubling wood production. Considering the mitigation effects of climate change by forests, it emerges that the increase in standing volume of forests in Romania is smaller than the additional harvest in Germany which serves fossil fuel substitution.展开更多
In this paper, a single product, multi-period, aggregate production planning problem is formulated as a linear-quadratic Gaussian (LQG) optimal control model with chance constraints on state and control variables. Suc...In this paper, a single product, multi-period, aggregate production planning problem is formulated as a linear-quadratic Gaussian (LQG) optimal control model with chance constraints on state and control variables. Such formulation is based on a classical production planning model developed in 1960 by Holt, Modigliani, Muth and Simon, and known, since then, as the HMMS model [1]. The proposed LQG model extends the HMMS model, taking into account both chance-constraints on the decision variables and data generating process, based on ARMA model, to represent the fluctuation of demand. Using the certainty-equivalence principle, the constrained LQG model can be transformed into an equivalent, but deterministic model, which is called here as Mean Value Problem (MVP). This problem preserves the main properties of the original model such as convexity and some statistical moments. Besides, it is easier to be implemented and solved numerically than its stochastic version. In addition, two very simple suboptimal procedures from stochastic control theory are briefly discussed. Finally, an illustrative example is introduced to show how the extended HMMS model can be used to develop plans and to generate production scenarios.展开更多
Generically, SCM may be said to include all activities carried out to ensure proper functioning of the supply chain. The activities included in proper management of a supply chain broadly include logistics activities,...Generically, SCM may be said to include all activities carried out to ensure proper functioning of the supply chain. The activities included in proper management of a supply chain broadly include logistics activities, planning and control of the flow of information and materials in a firm, management of relationships with other organizations and government intervention, However, crude oil theft and pipeline vandalism are established products supply chain disruptors in Nigeria which are rendering the task of running an efficient petroleum supply chain onerous. This paper aims to establish the importance of effective supply chain strategies for companies in the oil and gas industry with special focus on the Nigerian oil and gas sector and the strategies by which the state oil and gas corporation in this sector may mitigate disruptions to its supply chain. This study investigates the enhancement of supply chain strategies towards meeting the challenge of crude oil theft and pipeline vandalism, using the Nigerian National Corporation (NNPC) as a case study. Based on this study, data were collected from two sources: A summary of incident reports obtained from NNPC and an interview with personnel in the PPMC Department. Incident report refers to a report produced when accidents such as equipment failure, injury, loss of life, or fire occur at the work site. Content analysis is utilized to evaluate data obtained from interview responses, CBN financial stability reports, NDIC annual reports, circulars, banking supervision reports and implementation guidelines. The study found out that NNPC should endeavor to sustain its value chain and ward of pipeline vandals and crude oil thieves by engaging in community partnership, detailing security outfits to ensure its pipelines’ right of way and bridging. Concluded that the oil supply chain of the Nigerian National Petroleum Corporation has been plagued by disruptions in the form of crude oil theft and pipeline vandalism which has had debilitating effects on its value.展开更多
文摘Operations management is essential for gaining competitiveness in most manufacturing or service-offering organizations.Therefore,this report is going to analyze the way in which effective operations managers use process strategy as a competitive weapon.Besides,based on relevant theories,a case of fast food production process will be studied.
基金support by a grant of the Romanian National Authority for Scientific Research,CNCS-UEFISCDI,project number PN-II-ID-PCE-2011-3-0781support by a grant of the Romanian National Authority for Scientific Research,CNCS-UEFISCDI,project number PN-II-RU-TE-2014-4-0017
文摘Background： The quantitative impact of forest management on forests＇ wood resource was evaluated for Picea and Fagus mixed forests. The effects on the productivity of tendering operations, thinnings and rotation length have seldom been directly quantified on landscape scale. Methods： Two sites of similar fertility but subject to contrasted forest management were studied with detailed inventories： one in Germany, the other in Romania, and compared with the respective national forest inventories. In Romania, regulations impose very long rotations, low thinnings and a period of no-cut before harvest. In contrast, tending and thinnings are frequent and intense in Germany. Harvests start much earlier and must avoid clear cutting but maintain a permanent forest cover with natural regeneration. While Germany has an average annual wood increment representative for Central Europe, Romania represents the average for Eastern Europe. Results： The lack of tending and thinning in the Romanian site resulted in twice as many trees per hectare as in the German site for the same age. The productivity in Romanian production forests was 20 % lower than in Germany despite a similar fertility. The results were supported by the data from the national forest inventory of each country, which confirmed that the same differential exists at country scale. Furthermore, provided the difference in rotation length, two crops are harvested in Germany when only one is harvested in Romania. The losses of production due to a lower level of management in Romania where estimated to reach 12.8 million m3.y-1 in regular mountain production forests, and to 15 million m3.y-1 if managed protection forest is included. Conclusions： The productivity of Picea and Fagus mountain forests in Romania is severely depressed by the lack of tending and thinning, by overly long rotations and the existence of a 25-years no-cut period prior to harvest. The average standing volume in Germany was 50 % lower than in Romania, but the higher harvesting rate resulted in more than doubling wood production. Considering the mitigation effects of climate change by forests, it emerges that the increase in standing volume of forests in Romania is smaller than the additional harvest in Germany which serves fossil fuel substitution.
文摘In this paper, a single product, multi-period, aggregate production planning problem is formulated as a linear-quadratic Gaussian (LQG) optimal control model with chance constraints on state and control variables. Such formulation is based on a classical production planning model developed in 1960 by Holt, Modigliani, Muth and Simon, and known, since then, as the HMMS model [1]. The proposed LQG model extends the HMMS model, taking into account both chance-constraints on the decision variables and data generating process, based on ARMA model, to represent the fluctuation of demand. Using the certainty-equivalence principle, the constrained LQG model can be transformed into an equivalent, but deterministic model, which is called here as Mean Value Problem (MVP). This problem preserves the main properties of the original model such as convexity and some statistical moments. Besides, it is easier to be implemented and solved numerically than its stochastic version. In addition, two very simple suboptimal procedures from stochastic control theory are briefly discussed. Finally, an illustrative example is introduced to show how the extended HMMS model can be used to develop plans and to generate production scenarios.
文摘Generically, SCM may be said to include all activities carried out to ensure proper functioning of the supply chain. The activities included in proper management of a supply chain broadly include logistics activities, planning and control of the flow of information and materials in a firm, management of relationships with other organizations and government intervention, However, crude oil theft and pipeline vandalism are established products supply chain disruptors in Nigeria which are rendering the task of running an efficient petroleum supply chain onerous. This paper aims to establish the importance of effective supply chain strategies for companies in the oil and gas industry with special focus on the Nigerian oil and gas sector and the strategies by which the state oil and gas corporation in this sector may mitigate disruptions to its supply chain. This study investigates the enhancement of supply chain strategies towards meeting the challenge of crude oil theft and pipeline vandalism, using the Nigerian National Corporation (NNPC) as a case study. Based on this study, data were collected from two sources: A summary of incident reports obtained from NNPC and an interview with personnel in the PPMC Department. Incident report refers to a report produced when accidents such as equipment failure, injury, loss of life, or fire occur at the work site. Content analysis is utilized to evaluate data obtained from interview responses, CBN financial stability reports, NDIC annual reports, circulars, banking supervision reports and implementation guidelines. The study found out that NNPC should endeavor to sustain its value chain and ward of pipeline vandals and crude oil thieves by engaging in community partnership, detailing security outfits to ensure its pipelines’ right of way and bridging. Concluded that the oil supply chain of the Nigerian National Petroleum Corporation has been plagued by disruptions in the form of crude oil theft and pipeline vandalism which has had debilitating effects on its value.
