In the automotive industry, lean project</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Ver...In the automotive industry, lean project</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> and innovation creation come to life by being updated under the control of systematic interdisciplinary process flows. The lean product development process that changes the shell, defined under the light of the variables created by the competitive conditions, is today measured by the value flow efficiency and the global market spread of the final product. Consequently, the lean product development approach, which aims to identify and purify all the wastes that do none value or create value to the system or cause burdens in the new product development process, is shaped by step-by-step approvals in the flow. In the main automotive industry company practices within the scope of the research (3 national, 3 international), the beginning of the concept of lean in design is to define and optimize the steps in the product development process under the value stream map. Therefore, the product function for which the customer has paid for, the function of the new product or the physical structure used to meet the needs in question, the comfort, life, experience, innovations of the scope that constitute the new product concept are planned and verified and implemented in the simplified automotive design stages at the beginning of the lean product development process. In this research, initial automotive design objectives and stages are at the focal point of the innovation and added value creation brought by the concept of </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">“</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">lean</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">”</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> approach. The research is modelled on the determination of steps that do not create added value together with the points where the flow circuits’ or stems, the process is devalued, the interdisciplinary holistic studies intensify, the information and delay begin and end in the sequential and simultaneous design validation step transition stages, which are examined under the lean approach. As a visual and virtual tool that enables the elaboration of nominal values such as the total duration of the design verification stages and the influence of interdisciplinary stakeholders or the test level of the product design with the new product added, it reveals the value flow or losses. Hence research;from innovation creation and new product design steps, which constitute the initial stages of the lean product development process, to design verification analysis, the efficiency of the automotive company processes within the scope of the research has been measured by comparing using lean automotive design techniques, methods and concepts.展开更多
[Objective] The aim was to analyze the process and reason of the extreme heavy rainfall on June 15,2011 in Cold Lake in Qinghai.[Method] The weather,physical field and satellite of one extreme heavy rain in the cold l...[Objective] The aim was to analyze the process and reason of the extreme heavy rainfall on June 15,2011 in Cold Lake in Qinghai.[Method] The weather,physical field and satellite of one extreme heavy rain in the cold lake in Qinghai were expounded.[Result] The formation of the loop 'crooked neck' of high pressure,which on the one hand posed a typical situation in the circulation of heavy precipitation in Qinghai,and on the other hand,formed the southwest,southeast of the two water vapor transport in air,in addition to the small groove from the trough of Lake Balk hash and the split vortex plateau,resulted into the extreme heavy rainfall in Cold Lake.The presence of thermal low pressure 700 hPa was conducive to the accumulation of low energy and low-level moisture transport from the Qinghai region to the south of Qaidam Basin.[Conclusion] The resulting process was mainly due to heavy rain in the lower troposphere convergence,high-level divergence,high humidity areas and a strong vertical upward motion.展开更多
In this paper, the classical economic order quantity (EOQ) inventory model assumption that all items of a certain product received from a supplier are of perfect quality is relaxed. Another basic assumption that the...In this paper, the classical economic order quantity (EOQ) inventory model assumption that all items of a certain product received from a supplier are of perfect quality is relaxed. Another basic assumption that the payment for the items is made at the beginning of the inventory cycle when they are received is also eased. We consider an inventory situation where items received from the supplier are of two types of quality, perfect and imperfect, and a short deferral in payment is allowed. The split between perfect and imperfect quality items is assumed to follow a known probability distribution. Both qualities of items have continuous demands, and items of imperfect quality are sold at a discount. A mathematical model is developed using the net present value of all cash flows involved in the inventory cycle. A numerical method for obtaining the optimal order quantity is presented, and the impact of the short-term financing is analyzed. An example is presented to validate the equations and illustrate the results.展开更多
We analyze the propagation of electromagnetic fronts in unbounded electric conductors. Our analysis is based on the Maxwell model of electromagnetism that includes the displacement current and Ohm’s law in its simple...We analyze the propagation of electromagnetic fronts in unbounded electric conductors. Our analysis is based on the Maxwell model of electromagnetism that includes the displacement current and Ohm’s law in its simplest forms. A weak electromagnetic front is a propagating interface at which the electromagnetic field remains continuous while its first- and higher-order derivatives experience finite jump discontinuities. Remarkably, analysis of such fronts can be performed autonomously, <em>i</em>.<em>e</em>. strictly in terms of the quantities defined on the front. This property opens the possibility of establishing exact analytical solutions of the exact Maxwell system along with the evolution of the front.展开更多
The center conditions and bifurcation of limit cycles for a class of fifth degree systems are investigated.Two recursive formulas to compute singular quantities at infinity and at the origin are given.The first nine ...The center conditions and bifurcation of limit cycles for a class of fifth degree systems are investigated.Two recursive formulas to compute singular quantities at infinity and at the origin are given.The first nine singular point quantities at infinity and first seven singular point quantities at the origin for the system are given in order to get center conditions and study bifurcation of limit cycles.Two fifth degree systems are constructed.One allows the appearance of eight limit cycles in the neighborhood of infinity,which is the first example that a polynomial differential system bifurcates eight limit cycles at infinity.The other perturbs six limit cycles at the origin.展开更多
Net Primary Productivity (NPP) is the basis of the material and energy transport calculation in ecosystem studies. NPP directly reflects the production capacity of plant communities under natural conditions. Ecosystem...Net Primary Productivity (NPP) is the basis of the material and energy transport calculation in ecosystem studies. NPP directly reflects the production capacity of plant communities under natural conditions. Ecosystem services are hot topics in the field of ecology. Many studies calculate ecosystem service value based on NPP. Taking Guanshanhu District of Guiyang City, Guizhou Province as the research object, using TM, ETM<sup>+</sup>, Gaofen2 and MOD17A3HGF.006 as data sources, this paper analyzed the change of ecosystem service value based on NPP in 2000, 2010 and 2020. The results showed that the area of forest ecosystem increased during 2000-2010 and decreased during 2010-2020. The artificial surface grew rapidly from 1146.82 hm<sup>2</sup> to 7544.29 hm<sup>2</sup> during 2000-2020. The farmland ecosystem decreased from 13308.29 hm<sup>2</sup> to 6342.33 hm<sup>2</sup> during 2000-2020. With the dynamic changes in ecosystem spatial distribution and component structure, the total NPP in 2000, 2010 and 2020 was 12.58 × 10<sup>4</sup> t, 11.90 × 10<sup>4</sup> t and 11.78 × 10<sup>4</sup> t, respectively, showing a decreasing trend. The total value of natural and semi-natural ecosystems services based on NPP showed an increasing trend, which was ¥ 6.938 × 10<sup>8</sup> in 2000, ¥ 8.052 × 10<sup>8</sup> in 2010 and ¥ 10.306 × 10<sup>8</sup> in 2020 respectively. The ecosystem contributed the most to the ecological service value in 2000 was farmland, but in 2010 and 2020, it was the forest ecosystem. The ecological service value of grassland and wetland was relatively small, while the ratio of the wetland ecological service value displayed a decreasing trend. In the future, it is necessary to establish a strict pretrial system for land use, so as to effectively protect the natural and semi-natural ecosystems and fulfill the growing ecological demands of residents.展开更多
The trade-off and synergy relationship of ecosystem services is an important topic in the current assessment.The value of each service provided by the ecosystem is substantially affected by human activities,and conver...The trade-off and synergy relationship of ecosystem services is an important topic in the current assessment.The value of each service provided by the ecosystem is substantially affected by human activities,and conversely,its changes will also affect the relevant human decisions.Due to varying tradeoffs among ecosystem services and synergies between them that can either increase or decrease,it is difficult to optimize multiple ecosystem services simultaneously,making it a huge challenge for ecosystem management.This study firstly develops a global Gross Ecosystem Product(GEP)accounting framework.It uses remote sensing data with a spatial resolution of 1 km to estimate the ecosystem services of forests,wetlands,grasslands,deserts,and farmlands in 179 major countries in 2018.The results show that the range of global GEP values is USD 112e197 trillion,with an average value of USD 155 trillion(the constant price),and the ratio of GEP to gross domestic product(GDP)is 1.85.The tradeoffs and the synergies among different ecosystem services in each continent and income group have been further explored.We found a correspondence between the income levels and the synergy among ecosystem services within each nation.Among specific ecosystem services,there are strong synergies between oxygen release,climate regulation,and carbon sequestration services.A trade-off relationship has been observed between flood regulation and other services,such as water conservation and soil retention services in low-income countries.The results will help clarify the roles and the feedback mechanisms between different stakeholders and provide a scientific basis for optimizing ecosystem management and implementing ecological compensation schemes to enhance human well-being.展开更多
The article deals with an economic order quantity (EOQ) inventory model for deteriorating items in which the supplier provides the purchaser a permissible delay in payment. This is so when deterioration of units in th...The article deals with an economic order quantity (EOQ) inventory model for deteriorating items in which the supplier provides the purchaser a permissible delay in payment. This is so when deterioration of units in the inventory is subject to constant deterioration rate, demand rate is quadratic function of time and salvage value is associated with the deteriorated units. Shortages in the system are not allowed to occur. A mathematical formulation is developed when the supplier offers a permissible delay period to the customers under two circumstances: 1) when delay period is less than the cycle of time;and 2) when delay period is greater than the cycle of time. The method is suitable for the items like state-of-the-art aircrafts, super computers, laptops, android mobiles, seasonal items and machines and their spare parts. A solution procedure algorithm is given for finding the optimal order quantity which minimizes the total cost of an inventory system. The article includes numerical examples to support the effectiveness of the developed model. Finally, sensitivity analysis on some parameters on optimal solution is provided.展开更多
文摘In the automotive industry, lean project</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> and innovation creation come to life by being updated under the control of systematic interdisciplinary process flows. The lean product development process that changes the shell, defined under the light of the variables created by the competitive conditions, is today measured by the value flow efficiency and the global market spread of the final product. Consequently, the lean product development approach, which aims to identify and purify all the wastes that do none value or create value to the system or cause burdens in the new product development process, is shaped by step-by-step approvals in the flow. In the main automotive industry company practices within the scope of the research (3 national, 3 international), the beginning of the concept of lean in design is to define and optimize the steps in the product development process under the value stream map. Therefore, the product function for which the customer has paid for, the function of the new product or the physical structure used to meet the needs in question, the comfort, life, experience, innovations of the scope that constitute the new product concept are planned and verified and implemented in the simplified automotive design stages at the beginning of the lean product development process. In this research, initial automotive design objectives and stages are at the focal point of the innovation and added value creation brought by the concept of </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">“</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">lean</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">”</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> approach. The research is modelled on the determination of steps that do not create added value together with the points where the flow circuits’ or stems, the process is devalued, the interdisciplinary holistic studies intensify, the information and delay begin and end in the sequential and simultaneous design validation step transition stages, which are examined under the lean approach. As a visual and virtual tool that enables the elaboration of nominal values such as the total duration of the design verification stages and the influence of interdisciplinary stakeholders or the test level of the product design with the new product added, it reveals the value flow or losses. Hence research;from innovation creation and new product design steps, which constitute the initial stages of the lean product development process, to design verification analysis, the efficiency of the automotive company processes within the scope of the research has been measured by comparing using lean automotive design techniques, methods and concepts.
文摘[Objective] The aim was to analyze the process and reason of the extreme heavy rainfall on June 15,2011 in Cold Lake in Qinghai.[Method] The weather,physical field and satellite of one extreme heavy rain in the cold lake in Qinghai were expounded.[Result] The formation of the loop 'crooked neck' of high pressure,which on the one hand posed a typical situation in the circulation of heavy precipitation in Qinghai,and on the other hand,formed the southwest,southeast of the two water vapor transport in air,in addition to the small groove from the trough of Lake Balk hash and the split vortex plateau,resulted into the extreme heavy rainfall in Cold Lake.The presence of thermal low pressure 700 hPa was conducive to the accumulation of low energy and low-level moisture transport from the Qinghai region to the south of Qaidam Basin.[Conclusion] The resulting process was mainly due to heavy rain in the lower troposphere convergence,high-level divergence,high humidity areas and a strong vertical upward motion.
文摘In this paper, the classical economic order quantity (EOQ) inventory model assumption that all items of a certain product received from a supplier are of perfect quality is relaxed. Another basic assumption that the payment for the items is made at the beginning of the inventory cycle when they are received is also eased. We consider an inventory situation where items received from the supplier are of two types of quality, perfect and imperfect, and a short deferral in payment is allowed. The split between perfect and imperfect quality items is assumed to follow a known probability distribution. Both qualities of items have continuous demands, and items of imperfect quality are sold at a discount. A mathematical model is developed using the net present value of all cash flows involved in the inventory cycle. A numerical method for obtaining the optimal order quantity is presented, and the impact of the short-term financing is analyzed. An example is presented to validate the equations and illustrate the results.
文摘We analyze the propagation of electromagnetic fronts in unbounded electric conductors. Our analysis is based on the Maxwell model of electromagnetism that includes the displacement current and Ohm’s law in its simplest forms. A weak electromagnetic front is a propagating interface at which the electromagnetic field remains continuous while its first- and higher-order derivatives experience finite jump discontinuities. Remarkably, analysis of such fronts can be performed autonomously, <em>i</em>.<em>e</em>. strictly in terms of the quantities defined on the front. This property opens the possibility of establishing exact analytical solutions of the exact Maxwell system along with the evolution of the front.
基金Supported by Science Fund of the Education Departmentof Guangxi province( 2 0 0 3) and the NationalNatural Science Foundation of China( 1 0 361 0 0 3)
文摘The center conditions and bifurcation of limit cycles for a class of fifth degree systems are investigated.Two recursive formulas to compute singular quantities at infinity and at the origin are given.The first nine singular point quantities at infinity and first seven singular point quantities at the origin for the system are given in order to get center conditions and study bifurcation of limit cycles.Two fifth degree systems are constructed.One allows the appearance of eight limit cycles in the neighborhood of infinity,which is the first example that a polynomial differential system bifurcates eight limit cycles at infinity.The other perturbs six limit cycles at the origin.
文摘Net Primary Productivity (NPP) is the basis of the material and energy transport calculation in ecosystem studies. NPP directly reflects the production capacity of plant communities under natural conditions. Ecosystem services are hot topics in the field of ecology. Many studies calculate ecosystem service value based on NPP. Taking Guanshanhu District of Guiyang City, Guizhou Province as the research object, using TM, ETM<sup>+</sup>, Gaofen2 and MOD17A3HGF.006 as data sources, this paper analyzed the change of ecosystem service value based on NPP in 2000, 2010 and 2020. The results showed that the area of forest ecosystem increased during 2000-2010 and decreased during 2010-2020. The artificial surface grew rapidly from 1146.82 hm<sup>2</sup> to 7544.29 hm<sup>2</sup> during 2000-2020. The farmland ecosystem decreased from 13308.29 hm<sup>2</sup> to 6342.33 hm<sup>2</sup> during 2000-2020. With the dynamic changes in ecosystem spatial distribution and component structure, the total NPP in 2000, 2010 and 2020 was 12.58 × 10<sup>4</sup> t, 11.90 × 10<sup>4</sup> t and 11.78 × 10<sup>4</sup> t, respectively, showing a decreasing trend. The total value of natural and semi-natural ecosystems services based on NPP showed an increasing trend, which was ¥ 6.938 × 10<sup>8</sup> in 2000, ¥ 8.052 × 10<sup>8</sup> in 2010 and ¥ 10.306 × 10<sup>8</sup> in 2020 respectively. The ecosystem contributed the most to the ecological service value in 2000 was farmland, but in 2010 and 2020, it was the forest ecosystem. The ecological service value of grassland and wetland was relatively small, while the ratio of the wetland ecological service value displayed a decreasing trend. In the future, it is necessary to establish a strict pretrial system for land use, so as to effectively protect the natural and semi-natural ecosystems and fulfill the growing ecological demands of residents.
基金the National Natural Science Foundation of China(Grant No.42277491)for its support.
文摘The trade-off and synergy relationship of ecosystem services is an important topic in the current assessment.The value of each service provided by the ecosystem is substantially affected by human activities,and conversely,its changes will also affect the relevant human decisions.Due to varying tradeoffs among ecosystem services and synergies between them that can either increase or decrease,it is difficult to optimize multiple ecosystem services simultaneously,making it a huge challenge for ecosystem management.This study firstly develops a global Gross Ecosystem Product(GEP)accounting framework.It uses remote sensing data with a spatial resolution of 1 km to estimate the ecosystem services of forests,wetlands,grasslands,deserts,and farmlands in 179 major countries in 2018.The results show that the range of global GEP values is USD 112e197 trillion,with an average value of USD 155 trillion(the constant price),and the ratio of GEP to gross domestic product(GDP)is 1.85.The tradeoffs and the synergies among different ecosystem services in each continent and income group have been further explored.We found a correspondence between the income levels and the synergy among ecosystem services within each nation.Among specific ecosystem services,there are strong synergies between oxygen release,climate regulation,and carbon sequestration services.A trade-off relationship has been observed between flood regulation and other services,such as water conservation and soil retention services in low-income countries.The results will help clarify the roles and the feedback mechanisms between different stakeholders and provide a scientific basis for optimizing ecosystem management and implementing ecological compensation schemes to enhance human well-being.
文摘The article deals with an economic order quantity (EOQ) inventory model for deteriorating items in which the supplier provides the purchaser a permissible delay in payment. This is so when deterioration of units in the inventory is subject to constant deterioration rate, demand rate is quadratic function of time and salvage value is associated with the deteriorated units. Shortages in the system are not allowed to occur. A mathematical formulation is developed when the supplier offers a permissible delay period to the customers under two circumstances: 1) when delay period is less than the cycle of time;and 2) when delay period is greater than the cycle of time. The method is suitable for the items like state-of-the-art aircrafts, super computers, laptops, android mobiles, seasonal items and machines and their spare parts. A solution procedure algorithm is given for finding the optimal order quantity which minimizes the total cost of an inventory system. The article includes numerical examples to support the effectiveness of the developed model. Finally, sensitivity analysis on some parameters on optimal solution is provided.