Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit...Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit element increases.A subarray-based space-time coding(sub-STC)radar is explored to alleviate the range resolution reduction.For the proposed radar configuration,an identical waveform is transmitted and it introduces a small time offset in different subarrays.The multidimensional ambiguity function of sub-STC radar is defined by considering resolutions in multiple domains including the range,Doppler,angle and probing direction.Analyses on properties of the multi-dimensional ambiguity function of the sub-STC radar with regard to the spatial coverage,resolution performance and low sidelobes are also given.Results reveal that the range resolution and low sidelobes performance are improved with the proposed approach.展开更多
The solutions of the following bilinear stochastic differential equation are studied [GRAPHICS] where A(t)(k), B-t are (deterministic) continuous matrix-valued functions of t and w(1) (t),..., w(m) (t) are m independe...The solutions of the following bilinear stochastic differential equation are studied [GRAPHICS] where A(t)(k), B-t are (deterministic) continuous matrix-valued functions of t and w(1) (t),..., w(m) (t) are m independent standard Brownian motions. Conditions are given such that the solution is positive if the initial condition is positive. The equation the most probable path must satisfy is also derived and applied to a mathematical finance problem.展开更多
The stability of money demand function is an important issue in macroeconomic policy implementation. Money demand of Korean economy was estimated. Cointegration test with time dummy variables results show that there i...The stability of money demand function is an important issue in macroeconomic policy implementation. Money demand of Korean economy was estimated. Cointegration test with time dummy variables results show that there is not only long-run equilibrium relationship between money demand and macroeconomic variables, but also structural breaks in this equilibrium relationships. Least squares, state-space, and Marcov switching methods show that there also has been instability (or regime shifts) of parameters in money demand, especially over 1997 crisis and the early 2000s. This fact implies that monetary policy for stabilization might encounter big problems due to change (instability) of money demand.展开更多
Regional logistics demand forecast is the basis for government departments to make logistics planning and logistics related policies.It has the characteristics of a small amount of data and being nonlinear,so the trad...Regional logistics demand forecast is the basis for government departments to make logistics planning and logistics related policies.It has the characteristics of a small amount of data and being nonlinear,so the traditional prediction method can not guarantee the accuracy of prediction.Taking Xiamen City as an example,this paper selects the primary industry,the secondary industry,the tertiary industry,the total amount of investment in fixed assets,total import and export volume,per capita consumption expenditure,and the total retail sales of social consumer goods as the influencing factors,and uses a combining model least square and radial basis function(LS-RBF)neural network to analyze the related data from years 2000 to 2019,so as to predict the logistics demand from years 2020 to 2024.The model can well fit the training data,and the experimental results obtained from the comparison between the predicted value and the actual value in 2019 show that the error rate is very small.Therefore,the prediction results are reasonable and reliable.This method has high prediction accuracy,and it is suitable for irregular regional logistics demand forecast.展开更多
To address the fuzziness and variability in determining customer demand importance,a dynamic analysis method based on intuitionistic fuzzy numbers is proposed.First,selected customers use intuitionistic fuzzy numbers ...To address the fuzziness and variability in determining customer demand importance,a dynamic analysis method based on intuitionistic fuzzy numbers is proposed.First,selected customers use intuitionistic fuzzy numbers to represent the importance of each demand.Then,the preference information is aggregated using customer weights and time period weights through the intuitionistic fuzzy ordered weighted average operator,yielding a dynamic vector of the subjective importance of the demand index.Finally,the feasibility of the proposed method is demonstrated through an application example of a vibrating sorting screen.展开更多
This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Bas...This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Based on material deterioration mechanisms and incremental dynamic analysis, the time-evolving seismic demands of components were obtained in the form of marginal probability distributions. The time-varying dependences among bridge components were then captured with the best fitting copula function, which was selected from the commonly used copula classes by the empirical distribution based analysis method. The system time-variant fragility curves at different damage states were developed and the effects of time-varying dependences among components on the bridge system fragility were investigated. The results indicate the time-varying dependence among components significantly affects the time-variant fragility of the bridge system. The copula technique captures the nonlinear dependence among component seismic demands accurately and easily by separating the marginal distributions and the dependence among them.展开更多
Metal batteries that directly use active metals as anodes are considered as one of the most promising solutions to achieve the energy upgrade of battery technologies,while their practical application still suffers fro...Metal batteries that directly use active metals as anodes are considered as one of the most promising solutions to achieve the energy upgrade of battery technologies,while their practical application still suffers from dendrite problems.Functional carbon materials(FCMs)have demonstrated their great potential in suppressing metal dendrites benefitting from the multiple merits such as chemical tunability and capability of multi-dimensional structure assembly.Here,we initiate a review to present the recent progress in employing FCMs to deal with dendrite problems.It focuses on the surface chemistry and multi-dimensional carbon material engineering,which systematically overcomes the problems through diverse methods,such as reinforcing desolvation,improving interface compatibility,homogenizing electric field,buffering volume expansion and lattice mismatch.In addition,we also refine the long-standing debate about whether surface defects in FCMs are beneficial to suppress the metal dendrites or not,especially in the non-aqueous electrolyte regime.Finally,the remaining challenges for utilizing FCMs to suppress metal dendrites and the possible solutions are proposed to guide the future development.展开更多
This paper explores the use of archived data to calibrate volume delay functions (VDFs) and updates their input parameters (capacity and free-flow speed) for planning applications. The sensitivity analysis of speed to...This paper explores the use of archived data to calibrate volume delay functions (VDFs) and updates their input parameters (capacity and free-flow speed) for planning applications. The sensitivity analysis of speed to change in congestion level is performed to capture functional characteristics of VDFs in modeling specific facility types. Different sensitivity characteristics shown by the VDFs indicate that each function is suitable to a particular facility type. The results of sensitivity analysis are confirmed by the root mean square percent error (RMSPE) values calculated using the Orlando Urban Area Transportation Study (OUATS) model results and observed data. The modified Davidson’s function exhibits remarkable performance in nearly all facility types. The strength of the modified Davidson’s function across a broad range of facilities can be attributed to the flexibility of its tuning parameter, μ. Fitted Bureau of Public Road (BPR) and conical delay functions show lower RMSPE for uninterrupted flow facilities (freeways/expressways, managed lanes) and higher values for toll roads (which might have partial interruptions due to toll booths) and signalized arterials. Akcelik function underperforms on freeways/expressways and managed lanes but shows some improvements for toll roads and superior results for the signalized arterials. This was a desired strength of Akcelik function when modeling link travel speed on facilities where stopped delays were encountered.展开更多
Focused on finding out the relationship between passenger demands of P&R and its influencing factors, a nested-logit mode choice model was developed based on the characteristic of different modes and transfer rule...Focused on finding out the relationship between passenger demands of P&R and its influencing factors, a nested-logit mode choice model was developed based on the characteristic of different modes and transfer rules. The utility functions were given respectively according to the characteristic of each alternative. Passenger demands of different modes between O-D pairs were obtained by making use of the binary logit model. Then an equilibrium model for different modes was proposed. Under this condition, the approximate relationship between passenger demands of different modes and their characteristic indexes was modeled by the sensitivity analysis method. Shift volume among different modes was achieved by utilizing this model when their characteristic indexes were changed. A case study indicates that the model and algorithm presented in this paper are effective.展开更多
The change of vocal flinction after vocal fold dehydration due to dryness was discussed along with the treatment eHect of different atomizing agents.Forty-eight staffs from The Central Hospital of Wuhan were recniited...The change of vocal flinction after vocal fold dehydration due to dryness was discussed along with the treatment eHect of different atomizing agents.Forty-eight staffs from The Central Hospital of Wuhan were recniited.All volunteers breathed dry air for vocal fold dehydration.After dry air inhalation,the subjects were randomly divided into four groups,with 12 cases each.Three groups were treatment groups,receiving 0.9%nonnal saline(IS),5%hypertonic saline(HS)and double-distilled water(SW)atomizing inhalation therapy,respectively,and the last group was the control group without treatment.Voice data were collected for all subjects before and immediately after dry air inhalation using the Multi-Dimensional Voice Program(MDVP)system.Atomizing inhalation therapy was given 10 min after dry air inhalation,and voice data were collected using MDVP system at the following time points after atomizing inhalation treatment:5 min,20 min,35 min,50 min,65 min,80 min,95 min,110 min.In the control group,voice data were collected at the same time points and compared with those of treatment groups.The vocal function parameters collected before and after dry air inhalation as well as after treatment were subjected to test using SPSS 16.0 software.In the four groups,jitter(fundamental frequency perturbation),shimmer(amplitude perturbation),and amplitude perturbation quotient(APQ)were significantly increased after dry air inhalation(P<0.05).In IS,HS and SW groups,after atomizing inhalation treatment,there was an obvious reduction in jitter,shimmer and APQ,showing significant differences as compared with those after dry air inhalation(P<0.05).Moreover,these parameters were significantly lower than those in the control group(P<0.05).The jitter,shimmer and APQ in the IS group were significantly lower than those in the HS and SW groups(P<0.05).We are led to a con elusion:Vocal fold dehydration induced by dryness can reduce the stability of voice;such decreased voice stability can be improved by atomizing inhalation therapy;without proper treatment,voice stability caused by vocal fold dehydration cannot heal spontaneously;of three atomizing agents namely,IS,HS and SW,IS had the best treatment effect for decreased voice stability caused by vocal fold dehydration.展开更多
The existence of irreversible demand is tested, whereby price increases induce a different absolute magnitude of quantity change than price decreases. Irreversibility is potentially likely in retail food settings for ...The existence of irreversible demand is tested, whereby price increases induce a different absolute magnitude of quantity change than price decreases. Irreversibility is potentially likely in retail food settings for storable products that are consumed regularly and can affect pricing strategy performance. If irreversibility exists, the subsequent research question for storable product demand is whether loss aversion effects dominate stockpiling effects, or vice versa. A two-period theoretical model is developed, which predicts more elastic responses to downward price movements via stockpiling, but empirical tests on secondary data are needed to evaluate offsetting loss aversion effects. A variant of the Rotterdam demand model is developed to allow differential response to price increases and decreases. The model is applied to scanner data of short periodicity (weekly in this case), which are necessary to measure meaningful demand responses to food price changes. The products selected are U.S. cheeses and table spreads that are storable over multiple weeks. The results suggest that stockpiling dominates loss aversion. One potential cause of this behavior may be that marketers asymmetrically provide consumers with more reference price information when lowering prices, but not when raising prices. When stockpiling effects dominate, given the typically price-elastic store-level demand for food products, high-low pricing strategies should produce higher revenue. Regarding measurement of average demand response, reversible demand models applied to weekly data may overestimate own-price elasticities.展开更多
Forecasting is predicting or estimating a future event or trend.Supply chains have been constantly growing in most countries ever since the industrial revolution of the 18th century.As the competitiveness between supp...Forecasting is predicting or estimating a future event or trend.Supply chains have been constantly growing in most countries ever since the industrial revolution of the 18th century.As the competitiveness between supply chains intensifies day by day,companies are shifting their focus to predictive analytics techniques to minimize costs and boost productivity and profits.Excessive inventory(overstock)and stock outs are very significant issues for suppliers.Excessive inventory levels can lead to loss of revenue because the company's capital is tied up in excess inventory.Excess inventory can also lead to increased storage,insurance costs and labor as well as lower and degraded quality based on the nature of the product.Shortages or out of stock can lead to lost sales and a decline in customer contentment and loyalty to the store.If clients are unable to find the right products on the shelves,they may switch to another vendor or purchase alternative items.Demand forecasting is valuable for planning,scheduling and improving the coordination of all supply chain activities.This paper discusses the use of neural networks for seasonal time series forecasting.Our objective is to evaluate the contribution of the correct choice of the transfer function by proposing a new form of the transfer function to improve the quality of the forecast.展开更多
基金supported by the National Key Research and Development Program of China(2016YFE0200400)the Key R&D Program of Shaanxi Province(2017KW-ZD-12)+1 种基金the Postdoctoral Science Foundation of Shaanxi Provincethe Nature Science Foundation of Shaanxi Province
文摘Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit element increases.A subarray-based space-time coding(sub-STC)radar is explored to alleviate the range resolution reduction.For the proposed radar configuration,an identical waveform is transmitted and it introduces a small time offset in different subarrays.The multidimensional ambiguity function of sub-STC radar is defined by considering resolutions in multiple domains including the range,Doppler,angle and probing direction.Analyses on properties of the multi-dimensional ambiguity function of the sub-STC radar with regard to the spatial coverage,resolution performance and low sidelobes are also given.Results reveal that the range resolution and low sidelobes performance are improved with the proposed approach.
基金the General Research Fund of the University of Kansas.
文摘The solutions of the following bilinear stochastic differential equation are studied [GRAPHICS] where A(t)(k), B-t are (deterministic) continuous matrix-valued functions of t and w(1) (t),..., w(m) (t) are m independent standard Brownian motions. Conditions are given such that the solution is positive if the initial condition is positive. The equation the most probable path must satisfy is also derived and applied to a mathematical finance problem.
文摘The stability of money demand function is an important issue in macroeconomic policy implementation. Money demand of Korean economy was estimated. Cointegration test with time dummy variables results show that there is not only long-run equilibrium relationship between money demand and macroeconomic variables, but also structural breaks in this equilibrium relationships. Least squares, state-space, and Marcov switching methods show that there also has been instability (or regime shifts) of parameters in money demand, especially over 1997 crisis and the early 2000s. This fact implies that monetary policy for stabilization might encounter big problems due to change (instability) of money demand.
基金Social Science Research Project of Education Department of Fujian Province,China(No.JAS160571)Key Project of Education and Teaching Reform of Undergraduate Universities in Fujian Province,China(No.FBJG20190130)Educational Research Project of Social Science for Young and Middle Aged Teachers in Fujian Province,China(No.JAS19371)。
文摘Regional logistics demand forecast is the basis for government departments to make logistics planning and logistics related policies.It has the characteristics of a small amount of data and being nonlinear,so the traditional prediction method can not guarantee the accuracy of prediction.Taking Xiamen City as an example,this paper selects the primary industry,the secondary industry,the tertiary industry,the total amount of investment in fixed assets,total import and export volume,per capita consumption expenditure,and the total retail sales of social consumer goods as the influencing factors,and uses a combining model least square and radial basis function(LS-RBF)neural network to analyze the related data from years 2000 to 2019,so as to predict the logistics demand from years 2020 to 2024.The model can well fit the training data,and the experimental results obtained from the comparison between the predicted value and the actual value in 2019 show that the error rate is very small.Therefore,the prediction results are reasonable and reliable.This method has high prediction accuracy,and it is suitable for irregular regional logistics demand forecast.
文摘To address the fuzziness and variability in determining customer demand importance,a dynamic analysis method based on intuitionistic fuzzy numbers is proposed.First,selected customers use intuitionistic fuzzy numbers to represent the importance of each demand.Then,the preference information is aggregated using customer weights and time period weights through the intuitionistic fuzzy ordered weighted average operator,yielding a dynamic vector of the subjective importance of the demand index.Finally,the feasibility of the proposed method is demonstrated through an application example of a vibrating sorting screen.
基金Natural Science Foundation of China under Grant No.51808376
文摘This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Based on material deterioration mechanisms and incremental dynamic analysis, the time-evolving seismic demands of components were obtained in the form of marginal probability distributions. The time-varying dependences among bridge components were then captured with the best fitting copula function, which was selected from the commonly used copula classes by the empirical distribution based analysis method. The system time-variant fragility curves at different damage states were developed and the effects of time-varying dependences among components on the bridge system fragility were investigated. The results indicate the time-varying dependence among components significantly affects the time-variant fragility of the bridge system. The copula technique captures the nonlinear dependence among component seismic demands accurately and easily by separating the marginal distributions and the dependence among them.
基金supported by the Fundamental Research Funds for the Central Universities,China(buctrc202029,buctrc202129)the Beijing Nova Program(Z211100002121093)。
文摘Metal batteries that directly use active metals as anodes are considered as one of the most promising solutions to achieve the energy upgrade of battery technologies,while their practical application still suffers from dendrite problems.Functional carbon materials(FCMs)have demonstrated their great potential in suppressing metal dendrites benefitting from the multiple merits such as chemical tunability and capability of multi-dimensional structure assembly.Here,we initiate a review to present the recent progress in employing FCMs to deal with dendrite problems.It focuses on the surface chemistry and multi-dimensional carbon material engineering,which systematically overcomes the problems through diverse methods,such as reinforcing desolvation,improving interface compatibility,homogenizing electric field,buffering volume expansion and lattice mismatch.In addition,we also refine the long-standing debate about whether surface defects in FCMs are beneficial to suppress the metal dendrites or not,especially in the non-aqueous electrolyte regime.Finally,the remaining challenges for utilizing FCMs to suppress metal dendrites and the possible solutions are proposed to guide the future development.
文摘This paper explores the use of archived data to calibrate volume delay functions (VDFs) and updates their input parameters (capacity and free-flow speed) for planning applications. The sensitivity analysis of speed to change in congestion level is performed to capture functional characteristics of VDFs in modeling specific facility types. Different sensitivity characteristics shown by the VDFs indicate that each function is suitable to a particular facility type. The results of sensitivity analysis are confirmed by the root mean square percent error (RMSPE) values calculated using the Orlando Urban Area Transportation Study (OUATS) model results and observed data. The modified Davidson’s function exhibits remarkable performance in nearly all facility types. The strength of the modified Davidson’s function across a broad range of facilities can be attributed to the flexibility of its tuning parameter, μ. Fitted Bureau of Public Road (BPR) and conical delay functions show lower RMSPE for uninterrupted flow facilities (freeways/expressways, managed lanes) and higher values for toll roads (which might have partial interruptions due to toll booths) and signalized arterials. Akcelik function underperforms on freeways/expressways and managed lanes but shows some improvements for toll roads and superior results for the signalized arterials. This was a desired strength of Akcelik function when modeling link travel speed on facilities where stopped delays were encountered.
基金Sponsored by the National Project from Ministry of Science and Technology,China(Grant No.2006BAJ18B03)
文摘Focused on finding out the relationship between passenger demands of P&R and its influencing factors, a nested-logit mode choice model was developed based on the characteristic of different modes and transfer rules. The utility functions were given respectively according to the characteristic of each alternative. Passenger demands of different modes between O-D pairs were obtained by making use of the binary logit model. Then an equilibrium model for different modes was proposed. Under this condition, the approximate relationship between passenger demands of different modes and their characteristic indexes was modeled by the sensitivity analysis method. Shift volume among different modes was achieved by utilizing this model when their characteristic indexes were changed. A case study indicates that the model and algorithm presented in this paper are effective.
文摘The change of vocal flinction after vocal fold dehydration due to dryness was discussed along with the treatment eHect of different atomizing agents.Forty-eight staffs from The Central Hospital of Wuhan were recniited.All volunteers breathed dry air for vocal fold dehydration.After dry air inhalation,the subjects were randomly divided into four groups,with 12 cases each.Three groups were treatment groups,receiving 0.9%nonnal saline(IS),5%hypertonic saline(HS)and double-distilled water(SW)atomizing inhalation therapy,respectively,and the last group was the control group without treatment.Voice data were collected for all subjects before and immediately after dry air inhalation using the Multi-Dimensional Voice Program(MDVP)system.Atomizing inhalation therapy was given 10 min after dry air inhalation,and voice data were collected using MDVP system at the following time points after atomizing inhalation treatment:5 min,20 min,35 min,50 min,65 min,80 min,95 min,110 min.In the control group,voice data were collected at the same time points and compared with those of treatment groups.The vocal function parameters collected before and after dry air inhalation as well as after treatment were subjected to test using SPSS 16.0 software.In the four groups,jitter(fundamental frequency perturbation),shimmer(amplitude perturbation),and amplitude perturbation quotient(APQ)were significantly increased after dry air inhalation(P<0.05).In IS,HS and SW groups,after atomizing inhalation treatment,there was an obvious reduction in jitter,shimmer and APQ,showing significant differences as compared with those after dry air inhalation(P<0.05).Moreover,these parameters were significantly lower than those in the control group(P<0.05).The jitter,shimmer and APQ in the IS group were significantly lower than those in the HS and SW groups(P<0.05).We are led to a con elusion:Vocal fold dehydration induced by dryness can reduce the stability of voice;such decreased voice stability can be improved by atomizing inhalation therapy;without proper treatment,voice stability caused by vocal fold dehydration cannot heal spontaneously;of three atomizing agents namely,IS,HS and SW,IS had the best treatment effect for decreased voice stability caused by vocal fold dehydration.
文摘The existence of irreversible demand is tested, whereby price increases induce a different absolute magnitude of quantity change than price decreases. Irreversibility is potentially likely in retail food settings for storable products that are consumed regularly and can affect pricing strategy performance. If irreversibility exists, the subsequent research question for storable product demand is whether loss aversion effects dominate stockpiling effects, or vice versa. A two-period theoretical model is developed, which predicts more elastic responses to downward price movements via stockpiling, but empirical tests on secondary data are needed to evaluate offsetting loss aversion effects. A variant of the Rotterdam demand model is developed to allow differential response to price increases and decreases. The model is applied to scanner data of short periodicity (weekly in this case), which are necessary to measure meaningful demand responses to food price changes. The products selected are U.S. cheeses and table spreads that are storable over multiple weeks. The results suggest that stockpiling dominates loss aversion. One potential cause of this behavior may be that marketers asymmetrically provide consumers with more reference price information when lowering prices, but not when raising prices. When stockpiling effects dominate, given the typically price-elastic store-level demand for food products, high-low pricing strategies should produce higher revenue. Regarding measurement of average demand response, reversible demand models applied to weekly data may overestimate own-price elasticities.
文摘Forecasting is predicting or estimating a future event or trend.Supply chains have been constantly growing in most countries ever since the industrial revolution of the 18th century.As the competitiveness between supply chains intensifies day by day,companies are shifting their focus to predictive analytics techniques to minimize costs and boost productivity and profits.Excessive inventory(overstock)and stock outs are very significant issues for suppliers.Excessive inventory levels can lead to loss of revenue because the company's capital is tied up in excess inventory.Excess inventory can also lead to increased storage,insurance costs and labor as well as lower and degraded quality based on the nature of the product.Shortages or out of stock can lead to lost sales and a decline in customer contentment and loyalty to the store.If clients are unable to find the right products on the shelves,they may switch to another vendor or purchase alternative items.Demand forecasting is valuable for planning,scheduling and improving the coordination of all supply chain activities.This paper discusses the use of neural networks for seasonal time series forecasting.Our objective is to evaluate the contribution of the correct choice of the transfer function by proposing a new form of the transfer function to improve the quality of the forecast.