Two Warehouses Inventory Model with Quadratic Demand and Maximum Life Time

This paper deals with a two warehouses inventory model with quadratic demand. Due to some seasonal products, all time retailers not fulfill the demand of customers, so to solve this difficulty retailer storage some product for future sales in out of season. Here we consider two warehouses system, Own Warehouse (OW) and Rent Warehouse (RW). This paper considers maximum life time for the products and shortages are not allowed. Mathematical model of this paper is proposed to obtain the total cycle time and minimum inventory cost. A numerical example is give to validate this proposed model

A Two Warehouse Inventory Model with Stock-Dependent Demand and variable deterioration rate

In this paper we discuss a two warehouses inventory model for non-instantaneous deteriorating items. Throughout last so many years, mostly researchers have consideration to the situation where the demand rate is dependent on the level of the on-hand inventory. For inventory systems, such as fashionable commodities, the length of the waiting time for the next replenishment would determine whether the backlogging will be accepted or not. In real life situation, enterprises usually buy more goods than can be stored in their own warehouses (OW) for future production or sales. The surplus quantities are frequently stored in an extra storage space, represented by rented warehouses (RW).The rented warehouse is considered to charge high unit holding cost than the own warehouse. The necessary and sufficient conditions of the existence and uniqueness of the optimal solution are shown. We determine the optimal replenishment policy for non-instantaneous deteriorating items with partial backlogging and stock-dependent demand

Growth and Magnetic Properties of MnO₂-δ Nanowire Microspheres

We report the synthesis of MnO2-delta microspheres using hydrothermal and conventional chemical reaction methods. The microspheres of MnO2-delta consist of nanowires having a diameter of 20-50 nm and a length of 2-8 µm. The value of oxygen vacancy delta estimated from x-ray photoelectron spectrum is 0.3. The magnetization versus temperature curve indicates a magnetic transition at about 13 K. It is found that a parasitic ferromagnetic component is imposed on the antiferromagnetic structure of MnO2-delta, which might result from distortion of the lattice structure due to oxygen vacancies. The magnetic transition temperature TN is about 10 K lower than that of the bulk MnO2 single crystal

Observation of Novel Disordered Rhombohedral R₂Fe₁₇ (R=Rare Earth) Based Compounds

A recent study of (SmGd)Fe 14Si3 showed an anomalous x-ray diffraction pattern [P. C. Ezekwenna, G. K. Marasinghe, J.-H. Nam, W. J. James, W. B. Yelon, M. Ellouze, and Ph. I\u27Héritier, J. Appl. Phys. 87, 6716 (2000)]. Although all observed peaks could be indexed to the rhombohedral 2:17 phase (R-3m) many lines were strongly reduced in intensity. Subsequently, the same phenomenon was seen in neutron diffraction patterns from Nd2-xDysFe17-ySiy alloys and conventional refinement using the rhombohedral phase left significant residuals. Fourier mapping revealed additional density along the c-axis chains of Fe dumbbells and rare earth atoms. The perfect a-b-c stacking of the CaCu5 layers with regular 1/3 replacement of the rare earth atoms by Fe dumbbells appears to be broken. Detailed analysis shows that excess Fe dumbbells are incorporated into the structure and some reverse substitution is seen. In addition, the weak intensities are associated with a near equivalence of the 9d and 18h Fe sites, as in the parent CaCu5 phase. The relationship of this new structure to the other CaCu5 derived phases is described. The high Fe concentration creates the possibility of high TC and higher remanence than in the ordered 2:17 compounds

Structural, Magnetic, and Transport Properties of Zr-substituted La₀.₇ Sr₀.₃ Mn O₃

Zr-substituted perovskites La0.7Sr0.3 Mn1-x Zrx O3 with 0 ≤ x ≤ 0.20 were investigated by neutron diffraction (ND), magnetization, electric resistivity, and magnetoresistance measurements. ND refinements reveal that substituted Zr4+ goes only to the Mn site. Because of its large size, this leads to a Zr-solubility limit at x ≤ 0.10. The x ≤ 0.10 samples exhibit a rhombohedral structure (R3c) from 10 K to room temperature. For the x ≤ 0.10 samples, the cell parameters a and c, and volume increase continuously with increasing Zr content. In addition, the structural distortion of the Mn O6 octahedra increases with increasing Zr content. Zr-substituted La0.7 Sr0.3 Mn1-x Zrx O3 exhibits metallic behavior at low temperature. The field dependent resistivity suggests that electron-electron scattering is dominant and a two-magnon scattering process emerges with increasing temperature. The contribution from the two-magnon scattering in resistivity becomes larger with increasing Zr content. A maximum magnetoresistance (MRmax) of 35% is obtained for the x=0.03 sample at H=5 T. The MRmax shifts to a higher temperature region upon application of an external magnetic field

Electrical and Magnetotransport Properties of Canted Antiferromagnet Dy₅Si₂Ge₂

Summary form only given. Since the giant magnetocaloric effect is encountered in a ferromagnetic Gd5Si2Ge2 alloy near room temperature it is considered as a suitable material for magnetic refrigerator applications. Also a commensurate structural transition occurs at the magnetic transition temperature and there is a good correlation between the crystal structure and magnetic properties. Such observations have triggered numerous experimental studies on similar rare earth alloys and compounds. We have synthesized its Dy- analogue, namely, Dy5Si2Ge2 and have characterized it by means of room temperature X-ray diffraction, ac magnetic susceptibility (15 K - 300 K), electrical resistivity (at zero field and at 6 T), thermoelectric power (15 K - 300 K) and neutron diffraction (at 300 K and 9.2 K) experiments

Neutron and Magnetic Studies of La₀.₇Sr₀.₃Mn₁₋ₓCrₓO₃(x ≤ 0.7): A Homogeneous Charge-Ordered System

Structural and magnetic properties of La0.7Sr0.3Mn1-xCrxO3 (0 \u3c x ≤ 0.7) have been studied in order to determine the effect of substitution of Cr3+ for Mn3+. The data consist of neutron and x-ray powder-diffraction and magnetization measurements. We previously suggested these systems transition from ferromagnetic to antiferromagnetic ordering with the intermediate concentrations containing coexisting ferromagnetic and antiferromagnetic domains. Upon further detailed examination, we find that the neutron data can be fit using a single homogeneous long-range magnetically ordered state and compositionally dependent charge ordering. The magnetic structures are controlled by the competition between Mn-Mn, Mn-Cr, and Cr-Cr interactions (double exchange and superexchange). The metal to semimetal and semimetal to insulator transitions can be quantitatively described as due to the localization effect of superexchange. The presence of charge ordered states in the insulating region arises from the favorable energetics of Mn4+-O-Cr3+ superexchange bonds relative to Mn3+-O-Cr3+ bonds

Magnetic and Neutron Diffraction Studies on PrMnSb₂

Magnetic and neutron diffraction studies have been carried out on PrMnSb2. Magnetization data in the temperature range of 5-400 K show two magnetic transitions: one at ∼175 K attributed to the antiferromagnetic ordering of the Mn moments, and the other at ∼35 K possibly due to the antiferromagnetic ordering of the Pr moments. The magnetization-field isotherms at various temperatures are consistent with the above. Neutron diffraction data obtained at various temperatures can be fitted with a nearly antiferromagnetically coupled Mn moment of ∼3μB at 70 K. At 10 K, moments both on Mn (∼3.5μB) and Pr (∼0. 94μB) are ordered antiferromagnetically with small canting angle

Competing Magnetic Interactions in the Intermetallic Compound Ho₂Mn₃Si₅

The compound Ho2Mn3Si5 exhibits multiple magnetic transitions: (i) an ordering at ~78 K, (ii) a second magnetic transition at ~16 K, and (iii) an anomaly at ~4 K. Its paramagnetic Curie temperature is found to be small but positive. Assuming a free ion effective paramagnetic moment of 10.6µB for Ho3+ ion, the effective paramagnetic moment per Mn in this compound is calculated to be 1.73µB, which indicates the itinerant nature of Mn d electrons. The various transitions in magnetization data are perhaps due to the ordering of rare earth and Mn moments. The magnetization at 2 K in applied fields of up to 7 T has linear field dependence, indicating dominant antiferromagnetic interactions in the system. Neutron diffraction studies point to a complex amplitude modulated incommensurate magnetic structure at 9 K

Structural and Magnetic Properties of La₀.₇Sr₀.₃Mn₁₋ₓNiₓO₃ (x ≤ 0.4)

We have studied the structural and magnetic properties of La0.7Sr0.3Mn1-xNixO3 (x = 0.05, 0.1, 0.20, 0.30, and 0.40) perovskites using x-ray and neutron diffraction and magnetic measurements. Our data consist of neutron (γ = 1.479Å) and x-ray (γ = 1.5481Å; Cu Kα) powder diffraction and magnetization measurements. We previously suggested these systems transition from ferromagnetic to antiferromagnetic ordering with the intermediate concentrations containing coexisting domains of ferromagnetically and antiferromagnetically ordered states. Upon further detailed examination, we find that the samples are homogeneous and that neutron data can be fitted to a single long-range magnetically ordered state. The compositional dependent changes are driven by a shift in the dominant near neighbor interaction from ferromagnetic to antiferromagnetic. In the intermediate compositions, peaks previously identified as due to antiferromagnetic ordering, in fact arise from charge ordering; the system remains in a ferromagnetic state where the Ni moments are antiparallel to the Mn moments. This interpretation supersedes multiphase and spin glass models for these complex systems