Supply Hub in Industrial Park (SHIP): The value of freight consolidation

Industrial parks, characterized as a cluster of enterprises situated in one location to share common resources, have played an indispensible role in boosting regional economic and industrial development. However, further development has been impeded by the shortage of land space, especially for the construction of warehouses. This paper proposes the concept of Supply Hub in Industrial Park (SHIP) as a promising approach addressing this challenge. SHIP is defined as a public provider of warehousing and logistics services for manufacturing enterprises located within an industrial park. The research reported in this paper focuses on evaluating the value of freight consolidation, one of the typical benefits of applying the SHIP approach. Two mathematical models of the supply chain in a typical industrial park are formulated: with and without SHIP. Genetic Algorithm (GA) is applied for solving the two models, and sensitivity experiments are conducted for comparative analysis between the two scenarios. The computational results show that through consolidating shipments, SHIP brings benefits to the whole industrial park. Total cost savings resulted from the application of SHIP would increase with the size of the supply chain, the vehicle capacity, and the rates of fixed transportation costs and holding costs of finished products at manufacturers.     

Automated rangeland vegetation cover and density estimation using ground digital images and a spectral-contextual classifier

A method to estimate vegetation cover, density and background brightness parameters in a rangeland environment from low-altitude digital images is presented. A digital still-frame camera, mounted on a 5.2 m pole, is used to acquire images of the ground. The acquired images are then processed using an unsupervised spectral-contextual classifier to extract quantitative measurements automatically. The test results show that the extracted cover measures from the fully automated procedure provide an accuracy of 0.89 to 0.99, measured in kappa, compared with 0.36 to 0.58 and 0.79 to 0.95 from k -means clustering and maximum likelihood supervised classifications respectively. For the clump density measure, the proposed method had an error level ranging from 0 to -62%-hundreds of times less than those produced from both k -means and maximum likelihood classifications. The presented method overcomes human subjectivity inherent in other commonly used ground investigation methods for estimating vegetation cover. The results provide an accurate and objective reference for the calibration of models which relate the spectral reflectance recorded by remote sensors to quantitative measures of range condition.     

Modeling of microstructure effects on the mechanical behavior of ultrafine-grained nickels processed by hot isostatic pressing

Bulk ultrafine-grained nickel specimens having grain sizes in the range of 0.25-5 μm were consolidated by hot isostatic pressing technique. The resulting microstructures were characterized by transmission electron microscopy and X-ray diffraction analysis. Compression tests were carried out at room temperature and at strain rate of 1.6×10⁻⁴ s⁻¹. It was found that the measured yield strength does not follow the Hall-Petch law as a consequence of the presence of oxide phase. Therefore, the use of micromechanics based model, which takes into account only the Hall-Petch relationship at grain level for predicting the grain sized effects on mechanical behavior of this kind of materials, is not accurate yet. In this study, a modification made to the generalized self-consistent model was proposed for studying both grain size and oxide phase dependence of ultrafine-grained materials behavior. Because of the novel modification, an optimization procedure with two steps was required to identify the parameters of micromechanical model. An acceptable agreement between experimental and numerical results was achieved. Moreover, the influence of texture on the yield strength and the application of the proposed model to the spark plasma sintering processed materials were also discussed.     

Infrared emission properties and energy transfer in ZnO-SiO2:Yb composites

Intense near-infrared emission at 1 μm has been obtained in ZnO-SiO₂:Yb³⁺ composites via a facile sol-gel method upon broadband ultraviolet light excitation. Systematic optical measurements including static and time-resolved photoluminescence have been performed to elucidate the energy transfer from ZnO quantum dots to Yb³⁺ ions. The dependence of energy transfer efficiency on Yb³⁺ concentration has been investigated in detail. Codoping with Li⁺ ions leads to about twice enhancement of the near-infrared luminescence intensity around 1 μm at room temperature. The enhancement in the luminescence intensity could be mostly attributed to the modification of the local symmetry around Yb³⁺ ions by codoping with Li⁺ ions.     

Prediction of formation enthalpies for Al2X-type intermetallics using back-propagation neural network

A back-propagation artificial neural network (ANN) was established to predict the formation enthalpies of Al₂X-type intermetallics as a function of some physical parameters. These physical parameters include the electronegativity difference, the electron density difference, the atomic size difference, and the electron–atom ratio (e/a). The values calculated by the ANN method agree with experiments well to typically within 10%, indicating that the well-trained back-propagation (BP) neural network is feasible, and can precisely predict the formation enthalpies of Al₂X-type intermetallics. The method comparison based on the predicted formation enthalpies suggests that our ANN method is superior to Miedema's model. Some trends of formation enthalpies for Al₂X-type intermetallics were also observed from the ANN.     

Isocyanate-rich cellulose nanocrystals and their selective insertion in elastomeric polyurethane

Cellulose nanocrystals (CNC) were successfully obtained and modified with 1,6-hexamethylene diisocyanate (HDI) by means of in situ polymerization varying the CNC/HDI molar ratio to evaluate the number of anchored chains to the CNC. The modification was examined by elemental analysis, nuclear magnetic resonance (¹³C NMR) and attenuated total reflection Fourier transform infrared spectroscopy (IR-ATR). Nanocomposites containing 1.5 wt% CNC, modified and unmodified, were prepared by solvent casting. Thermal and mechanical properties of the resulting films were evaluated from the viewpoint of polyurethane microphase separated structure, soft and hard domains. CNC were effectively dispersed in the polyurethane matrix and depending on surface chemistry, the nanoreinforcement interacts selectively with matrix nanodomains. This interpretation is supported by differences in thermal and mechanical properties of the nanocomposites and also confirmed by AFM images. Isocyanate rich cellulose nanocrystals interacted with matrix hard phase, promoting physical association with hard segments, enhancing stiffness and dimensional stability versus temperature of the nanocomposite.     

A brief note on the counter-intuitive region of a square plate

This paper presents a numerical investigation of the counter-intuitive response in elastic, perfectly plastic square plates subjected to impulsive loading. A map of the counter-intuitive region is obtained based on non-dimensional numbers. Asymmetrical response of square plates in the counter-intuitive region is also reported.     

Analytical Mode III electromagnetic permeable cracks in magnetoelectroelastic materials

Fracture mechanism is pertinent to minimize the catastrophic failures and optimize the structural design. An exact treatment on the electromagnetic permeable crack problems in a magnetoelectroelastic medium is presented by establishing a Hamiltonian system in terms of the symplectic eigenfunctions. The coefficients of the series are determined from the lateral boundary conditions at the crack surfaces and the outer boundary conditions along the geometric domain. Analytical formulations of intensity factors and distributions of dual variables are obtained by the symplectic expansion method. The various intensity factors are directly related to the first few terms of the non-zero eigenvalue solutions.