Consider the reducibility of a class of nonlinear quasi-periodic systems with multiple eigenvalues under perturbational hypothesis in the neighborhood of equilibrium. That is, consider the following system x = （A ＋ ...Consider the reducibility of a class of nonlinear quasi-periodic systems with multiple eigenvalues under perturbational hypothesis in the neighborhood of equilibrium. That is, consider the following system x = （A ＋ εQ（ t） ）x ＋ eg（t） ＋ h（x, t）, where A is a constant matrix with multiple eigenvalues; h = O（x2） （x-4）） ; and h（x, t）, Q（t）, and g（t） are analytic quasi-periodic with respect to t with the same frequencies. Under suitable hypotheses of non-resonance conditions and non-degeneracy conditions, for most sufficiently small ε, the system can be reducible to a nonlinear quasi-periodic system with an equilibrium point by means of a quasi-periodic transformation.展开更多
Hydraulic pumps belong to reliable long-life hydraulic components. The reliability evaluation includes characters such as long test period,high cost,and high power loss and so on. Based on the principle of energy-savi...Hydraulic pumps belong to reliable long-life hydraulic components. The reliability evaluation includes characters such as long test period,high cost,and high power loss and so on. Based on the principle of energy-saving and power recovery,a small sample hydraulic pump reliability test rig is built,and the service life of hydraulic pump is predicted,and then the sampling period of reliability test is optimized. On the basis of considering the performance degradation mechanism of hydraulic pump,the feature information of degradation distribution of hydraulic pump volumetric efficiency during the test is collected,so an optimal degradation path model of feature information is selected from the aspect of fitting accuracy,and pseudo life data are obtained. Then a small sample reliability test of period constrained optimization search strategy for hydraulic pump is constructed to solve the optimization problem of the test sampling period and tightening end threshold,and it is verified that the accuracy of the minimum sampling period by the non-parametric hypothes is tested. Simulation result shows it could possess instructional significance and referenced value for hydraulic pump reliability life evaluation and the test's research and design.展开更多
In this study, the undrained behaviour of silt under low stress level is studied. An effective preparation method for built-in silt samples in the triaxial test was firstly developed. By triaxial testing of samples at...In this study, the undrained behaviour of silt under low stress level is studied. An effective preparation method for built-in silt samples in the triaxial test was firstly developed. By triaxial testing of samples at low confining pressures it was found that silt easily loses stability and liquefies. Loose silt may show temporary liquefaction under static loading, and develop full liquefaction under cyclic loading. The most important factors influencing the silt behaviour are porosity, confining pressure, consolidation state, cyclic loading level and number of cycles. The maximum obtainable shear stress is primarily a function of the confining pressure and the internal frictional angle. The actual structure of the silt material is the key factor in controlling its behaviour.展开更多
The typical industry practice for Tension Leg Platform （TLP） design focuses on a conventional short-term design recipe, which assumes that an N-year design environment leads to an N-year response. In the response-ba...The typical industry practice for Tension Leg Platform （TLP） design focuses on a conventional short-term design recipe, which assumes that an N-year design environment leads to an N-year response. In the response-based design method, the TLP is designed to withstand N-year responses rather than respond to N-year environmental conditions. In this paper, we present an overview and a general procedure for the response-based design method and use a case study to compare the critical TLP responses between the two methods. The results of our comparison show that the conventional short-term design method often contains an element of conservatism and that the response-based design method can reduce the design conditions and thereby achieve cost savings.展开更多
2017.09 Released by Cotton Incorporated Recent price movement NY futures and the A Index were influenced by U.S.crop expectations over the past month.Chinese prices were affected by exchange rates.South Asian prices w...2017.09 Released by Cotton Incorporated Recent price movement NY futures and the A Index were influenced by U.S.crop expectations over the past month.Chinese prices were affected by exchange rates.South Asian prices were flat or lower.After collapsing with the release of a higher U.S.production forecast in last month＇s report,NY futures moved higher with production-related concerns stemming from the arrival of two major.展开更多
A vector autoregressive model was developed for a sample of container carrier time charter rates. Although the series of time charter rates are themselves found non-stationary, thus precluding the use of many modeling...A vector autoregressive model was developed for a sample of container carrier time charter rates. Although the series of time charter rates are themselves found non-stationary, thus precluding the use of many modeling methodologies, evidence provided by co-integration tests points to the existence of stable long-term relationships between the series. An assessment of the forecasts derived from the model suggests that the spec-ification of these long-term relationships does not improve the accuracy of long-term forecasts. These results are interpreted as a corroboration of the efficient market hypothesis.展开更多
2015.5 Recent price movement After trending higher from midMarch through the end of April,values for NY futures and the A Index turned lower in May.Chinese prices have been stable,while Indian and Pakistani prices inc...2015.5 Recent price movement After trending higher from midMarch through the end of April,values for NY futures and the A Index turned lower in May.Chinese prices have been stable,while Indian and Pakistani prices increased.Prices for the nearby July contract(NY futures)met resistance near 68 cents/展开更多
In the global supply chain in a setting characterized by exchange rate uncertainties,it is quite necessary to focus on comparative research trying to find out which kind of purchasing strategy is better in different s...In the global supply chain in a setting characterized by exchange rate uncertainties,it is quite necessary to focus on comparative research trying to find out which kind of purchasing strategy is better in different situations.The two common global purchasing strategies,risk sharing(RS)and quantity flexibility(QF),are selected to be compared.Using a real-options approach,the valuation models of RS and QF purchasing contracts are established.By means of binomial lattice technique,numerical simulation and sensitivity analysis of two stochastic dynamic programs are presented.The effects on expected discounted value by changing relative parameters are described clearly.Based on comparative analysis,it is concluded that the QF purchasing strategy is better than that of the RS especially where great volatility exists for exchange rate processes in the global supply chain.展开更多
Over all fuel condition and the money we spend on the said fuel leads us to think about savings. What can we do？ As individuals, we can educate our students and their family members. The easiest way to do that is to ...Over all fuel condition and the money we spend on the said fuel leads us to think about savings. What can we do？ As individuals, we can educate our students and their family members. The easiest way to do that is to monitor their weekly spending for them. Together with their family members, the students have to monitor the consumption of electrical energy through three weeks. In the first week, they should spend electricity as they do everyday. During the second week they have the increase of spending of electrical energy. The third week is the saving energy week. They have to make a plan with their family members on how to save energy, for example, turning offthe lights in the empty rooms, turning offthe TV when there is no one watching it, etc.. Every week they have to note the data in kilowatts. When they acquire all the information and transform it into money they can see if it＇s worth saving electrical energy or not. They will see they don＇t have to give up the comforts of the modern life. The value of the project is in the fact that many households continue with the electrical energy saving. In fact, the number of the households is increasing.展开更多
Although, there are numerous empirical studies that explore option pricing on vacant land, there is hardly such study based on a South African case study. Moreover, phenomena observed in certain countries are not alwa...Although, there are numerous empirical studies that explore option pricing on vacant land, there is hardly such study based on a South African case study. Moreover, phenomena observed in certain countries are not always prevalent due to different economic circumstances. This case study explores option value emerging on vacant land due to office building in the Northern Suburbs of Johannesburg, South Africa （ZA） because land value ＂increased＂ in ＂price＂. Since late 1990s, Northern Suburbs are one of the most expensive areas of Johannesburg. Samuelson-McKean （1965） model is used to calculate option value on vacant land （Geltner ＆ Miller, 2001） and the model is used to estimate option values, first, when there are no costs, then when total costs are taken into account and lastly, when improvements are taken into account. The results are synonymous with option pricing theory （OPT） in sense that costs and land improvements increase option value; however, the impact of fixed costs on option value is debatable as fixed costs lead to an increase in option value while according to OPT they should not as fixed costs could easily be ＂hedged＂.展开更多
文摘Consider the reducibility of a class of nonlinear quasi-periodic systems with multiple eigenvalues under perturbational hypothesis in the neighborhood of equilibrium. That is, consider the following system x = （A ＋ εQ（ t） ）x ＋ eg（t） ＋ h（x, t）, where A is a constant matrix with multiple eigenvalues; h = O（x2） （x-4）） ; and h（x, t）, Q（t）, and g（t） are analytic quasi-periodic with respect to t with the same frequencies. Under suitable hypotheses of non-resonance conditions and non-degeneracy conditions, for most sufficiently small ε, the system can be reducible to a nonlinear quasi-periodic system with an equilibrium point by means of a quasi-periodic transformation.
基金Supported by the National Natural Science Foundation of China(No.51405424,11673040)the Special Scientific Research Fund of Public Welfare for Quality Inspection(No.201510202)
文摘Hydraulic pumps belong to reliable long-life hydraulic components. The reliability evaluation includes characters such as long test period,high cost,and high power loss and so on. Based on the principle of energy-saving and power recovery,a small sample hydraulic pump reliability test rig is built,and the service life of hydraulic pump is predicted,and then the sampling period of reliability test is optimized. On the basis of considering the performance degradation mechanism of hydraulic pump,the feature information of degradation distribution of hydraulic pump volumetric efficiency during the test is collected,so an optimal degradation path model of feature information is selected from the aspect of fitting accuracy,and pseudo life data are obtained. Then a small sample reliability test of period constrained optimization search strategy for hydraulic pump is constructed to solve the optimization problem of the test sampling period and tightening end threshold,and it is verified that the accuracy of the minimum sampling period by the non-parametric hypothes is tested. Simulation result shows it could possess instructional significance and referenced value for hydraulic pump reliability life evaluation and the test's research and design.
基金This research is partly supported by the National Natural Science Foundation(No.50009002)863(No.2001AA616020)projects.
文摘In this study, the undrained behaviour of silt under low stress level is studied. An effective preparation method for built-in silt samples in the triaxial test was firstly developed. By triaxial testing of samples at low confining pressures it was found that silt easily loses stability and liquefies. Loose silt may show temporary liquefaction under static loading, and develop full liquefaction under cyclic loading. The most important factors influencing the silt behaviour are porosity, confining pressure, consolidation state, cyclic loading level and number of cycles. The maximum obtainable shear stress is primarily a function of the confining pressure and the internal frictional angle. The actual structure of the silt material is the key factor in controlling its behaviour.
文摘The typical industry practice for Tension Leg Platform （TLP） design focuses on a conventional short-term design recipe, which assumes that an N-year design environment leads to an N-year response. In the response-based design method, the TLP is designed to withstand N-year responses rather than respond to N-year environmental conditions. In this paper, we present an overview and a general procedure for the response-based design method and use a case study to compare the critical TLP responses between the two methods. The results of our comparison show that the conventional short-term design method often contains an element of conservatism and that the response-based design method can reduce the design conditions and thereby achieve cost savings.
文摘2017.09 Released by Cotton Incorporated Recent price movement NY futures and the A Index were influenced by U.S.crop expectations over the past month.Chinese prices were affected by exchange rates.South Asian prices were flat or lower.After collapsing with the release of a higher U.S.production forecast in last month＇s report,NY futures moved higher with production-related concerns stemming from the arrival of two major.
文摘A vector autoregressive model was developed for a sample of container carrier time charter rates. Although the series of time charter rates are themselves found non-stationary, thus precluding the use of many modeling methodologies, evidence provided by co-integration tests points to the existence of stable long-term relationships between the series. An assessment of the forecasts derived from the model suggests that the spec-ification of these long-term relationships does not improve the accuracy of long-term forecasts. These results are interpreted as a corroboration of the efficient market hypothesis.
文摘2015.5 Recent price movement After trending higher from midMarch through the end of April,values for NY futures and the A Index turned lower in May.Chinese prices have been stable,while Indian and Pakistani prices increased.Prices for the nearby July contract(NY futures)met resistance near 68 cents/
基金The National Key Technology R&D Program of China during the 11th Five-Year Plan Period(No.2006BAH02A06)CSC(China Scholarship Council)Scholarship Program for Graduate Student Studying Abroad 2007
文摘In the global supply chain in a setting characterized by exchange rate uncertainties,it is quite necessary to focus on comparative research trying to find out which kind of purchasing strategy is better in different situations.The two common global purchasing strategies,risk sharing(RS)and quantity flexibility(QF),are selected to be compared.Using a real-options approach,the valuation models of RS and QF purchasing contracts are established.By means of binomial lattice technique,numerical simulation and sensitivity analysis of two stochastic dynamic programs are presented.The effects on expected discounted value by changing relative parameters are described clearly.Based on comparative analysis,it is concluded that the QF purchasing strategy is better than that of the RS especially where great volatility exists for exchange rate processes in the global supply chain.
文摘Over all fuel condition and the money we spend on the said fuel leads us to think about savings. What can we do？ As individuals, we can educate our students and their family members. The easiest way to do that is to monitor their weekly spending for them. Together with their family members, the students have to monitor the consumption of electrical energy through three weeks. In the first week, they should spend electricity as they do everyday. During the second week they have the increase of spending of electrical energy. The third week is the saving energy week. They have to make a plan with their family members on how to save energy, for example, turning offthe lights in the empty rooms, turning offthe TV when there is no one watching it, etc.. Every week they have to note the data in kilowatts. When they acquire all the information and transform it into money they can see if it＇s worth saving electrical energy or not. They will see they don＇t have to give up the comforts of the modern life. The value of the project is in the fact that many households continue with the electrical energy saving. In fact, the number of the households is increasing.
文摘Although, there are numerous empirical studies that explore option pricing on vacant land, there is hardly such study based on a South African case study. Moreover, phenomena observed in certain countries are not always prevalent due to different economic circumstances. This case study explores option value emerging on vacant land due to office building in the Northern Suburbs of Johannesburg, South Africa （ZA） because land value ＂increased＂ in ＂price＂. Since late 1990s, Northern Suburbs are one of the most expensive areas of Johannesburg. Samuelson-McKean （1965） model is used to calculate option value on vacant land （Geltner ＆ Miller, 2001） and the model is used to estimate option values, first, when there are no costs, then when total costs are taken into account and lastly, when improvements are taken into account. The results are synonymous with option pricing theory （OPT） in sense that costs and land improvements increase option value; however, the impact of fixed costs on option value is debatable as fixed costs lead to an increase in option value while according to OPT they should not as fixed costs could easily be ＂hedged＂.
