Inflation and time value of money in a vendor-buyer inventory system with transportation cost and ordering cost reduction

The article presents a single-vendor and a single-buyer integrated production inventory system with inflation and the time value of money.The main focus is on the effect of ordering cost reduction dependent on lead time and lead time reduction.Two integrated continuous review models are developed.For both cases,our objective is to minimise the total integrated system cost by simultaneously optimising the order quantity,safety factor,lead time and number of shipments.We take the transportation cost as a function of the shipment lot size and it is taken to be in an all unit-discount cost format.Thus we incorporate transportation cost explicitly into the model and develop optimal solution procedure for solving the proposed inventory system.An efficient algorithm for finding the optimal solution is developed and numerical examples are given to illustrate the model.

Measurement of the echo reduction for underwater acoustic passive materials by using the time reversal technique

A measuring method of the echo reduction of passive materials by using the time reversal（TR） technique is presented. To measure the echo reduction of a sample with this approach, the received signals are firstly focused according to the TR theory. Then, the sample is removed and the TR processing is again employed to realize the focus of the received signal.Finally, the echo reduction of the sample is evaluated with these focusing signals. Besides, to calibrate the measured echo reduction via the TR technique, a standard sample is employed to measure a constant coefficient that only depends on the measurement environment. An aluminum plate sample and a steel plate sample with the same size of 1.1 mxl.O m x0.005 m axe tested in a wave guide tank. The experimental results show that the calibrated values are well consistent with theoretical results under the free field at the measured frequency range of0.5-20 kHz. The relative errors of all the measured values are less than 10% and the values of the expanded uncertainty are less than 1.5 dB. The TR processing focuses the energy in spatial domain and temporal domain, so it can be used to measure the echo reduction of passive materials in the environments with reflections induced by boundaries and low frequency sources.

Statistical analyses of Global U-Pb Database 2017

The method of obtaining zircon samples affects estimation of the global U-Pb age distribution.Researchers typically collect zircons via convenience sampling and cluster sampling.When using these techniques,weight adjustments proportional to the areas of the sampled regions improve upon unweighted estimates.Here,grid-area and modern sediment methods are used to weight the samples from a new database of 418,967 U-Pb ages.Preliminary tests involve two age models.Model-1 uses the most precise U-Pb ages as the best ages.Model-2 uses the^(206)Pb/^(238)U age as the best age if it is less than a1000 Ma cutoff,otherwise it uses the^(207)Pb/^(206)Pb age as the best age.A correlation analysis between the Model-1 and Model-2 ages indicates nearly identical distributions for both models.However,after applying acceptance criteria to include only the most precise analyses with minimal discordance,a histogram of the rejected samples shows excessive rejection of the Model-2 analyses around the1000 Ma cutoff point.Because of the excessive rejection rate for Model-2,we select Model-1 as the preferred model.After eliminating all rejected samples,the remaining analyses use only Model-1 ages for five rock-type subsets of the database:igneous,meta-igneous,sedimentary,meta-sedimentary,and modern sediments.Next,time-series plots,cross-correlation analyses,and spectral analyses determine the degree of alignment among the time-series and their periodicity.For all rock types,the U-Pb age distributions are similar for ages older than 500 Ma,but align poorly for ages younger than 500 Ma.The similarities(>500 Ma)and differences(<500 Ma)highlight how reductionism from a detailed database enhances understanding of time-dependent sequences,such as erosion,detrital transport mechanisms,lithification,and metamorphism.Time-series analyses and spectral analyses of the age distributions predominantly indicate a synchronous period-tripling sequence of^91-Myr,~273-Myr,and^819-Myr among the various rock types.

THE INVESTIGATION OF VORTEX METHOD AND ITS APPLICATION TO DRAG REDUCTION TECHNOLOGY

The flow past a circular cylinder and airfoil with varying mathematical roughness function are numerically simulated. A new model about blowing and suction is constructed by using the concept of mathematical roughness function. The flow field and the drag are investigated through this new model. By the numerical study about bluff body, some conclusions are drawn to reduce the drag.

Drag-reduction behavior of an unusual nonionic surfactant in a circular pipe turbulent flow

The Alkyl Polyglucoside（APG） is a nonionic surfactant with no toxicity and with high biodegradability, its drag-reduction behavior in a circular pipe flow is measured, and the rheological characteristics are investigated with a rheometer with a cone-plate flow cell. From the measured results, the APG is shown to have a high drag-reduction capacity, whose shear viscosity is shear-ratedependent at high concentrations, while its solution at concentrations with drag-reduction effects is non-viscoelastic as verified by zero relaxation time in the relaxation process of the shear stress, which contradicts the general viewpoint that there is a correlation between the viscoselastic characteristics and the turbulent drag reduction for the drag-reduction surfactant. However, the APG solution is birefringent as observed through a birefringent test, which indicates that there are rod-shaped micelles in the solution under the shearing flow. The higher extensional viscosity inferred from the extensional phenomenon observed in the measurements of the shear viscosity could be responsible for the drag reduction property of this nonionic surfactant.