A fuzzy MCDM model for allocating orders to suppliers in a supply chain under uncertainty over a multi-period time horizon

Allocating orders to suppliers is of a great importance in managing the supply chain. This process comes after supplier selection and evaluation. Having selected the qualified vendors, the manager will examine the performance of each one and evaluate the individual vendor. According to the results of periodic evaluations, the manager allocates orders to suppliers. Splitting orders among suppliers is so important that it may influence the efficiency of the whole chain. In this paper, we propose a fuzzy multi-criterion model for organizing the process of assigning orders to suppliers. We adopt a fuzzy approach in order to overcome the vagueness of the information due to the uncertainty of them. MCDM methods are used to allocate suitable shares of orders to the best possible suppliers. Different from previous works, we discuss this problem over a multi-period time horizon; namely, the model leads to solutions which optimize the order in both the whole year and the fractional periods of a year. A fuzzy linear programming model is developed to optimize the price, quality and risk objectives and satisfy constraints like logistics costs, suppliers′ capacity, supply chain demand, risk, etc. A numerical example comes to validate our proposed model.     

Preparation of Zinc(II) Oxide Nanoparticles from a New Nano-Size Coordination Polymer Constructed from a Polypyridyl Amidic Ligand; Spectroscopic, Photoluminescence and Thermal Analysis Studies

A new zinc(II) coordination polymer, {[Zn(bpcdp)₂(DMF)₄](ClO₄)₂·(H₂O)₂}_n (1) bpcdp = 2,6-bis(4-pyridinecarboxamide)pyridine has been synthesized and characterized by IR, ¹HNMR and ¹³CNMR spectroscopy. The single crystal X-ray data of compound 1 shows the zinc(II) atom has been considered as octahedral with ZnN₂O₄ coordination sphere. Two nitrogen atoms of bpcdp ligand and four oxygen atoms of DMF molecules have occupied coordination sphere around zinc(II) atoms. The prepared zinc(II) coordination polymer grows in three-dimensional network by hydrogen bonding and π–π stacking interaction. The nanostructure of compound 1 were obtained by sonochemical process and studied by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), IR and NMR spectroscopy. Thermal stabilities of single crystalline and nano-size samples of compound 1 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The ZnO nanoparticles were obtained by direct calcination of compound 1 at 400 °C and by thermolysis in oleic acid at 200 °C. The obtained zinc(II) oxide nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

Enhanced Polar Magneto-optical Kerr Rotation in Cobalt Thin Film Incorporating Ag Nanoparticles

We report an experimental study on the effect of Ag nanoparticles on the polar magneto-optical Kerr effect in cobalt thin film. The magneto-optical cobalt thin film was prepared by electron beam deposition method onto the Ag nanoparticles which were synthesized by laser ablation in liquid technique. Our results indicate that we have sufficient enhancement of polar magneto-optical Kerr effect of cobalt thin film around the surface plasmon resonance of Ag nanoparticles. Moreover, combination of surface plasmon resonance of the Ag nanoparticles and very thin Au layer can be attained the enhancement factor in all of visible spectral region.     

Performance Analysis of Time Reversal UWB Communication with Non-coherent Energy Detector

Non-coherent receivers, such as energy detectors (ED), are the simplest and the most practical alternatives to coherent receivers for low-rate and low-complexity applications in ultra-wideband (UWB) systems. However, these advantages are achieved at the expense of non-negligible performance degradation. One solution to improve the performance is to make use of time reversal (TR) technique. In this study, the performance of TR technique with non-coherent ED is analyzed in UWB systems. First, we derive an approximate analytical formula for the error probability of TR-ED which is based on tapped-delay line (TDL) channel model. Next, we theoretically and by simulations analyze the optimum integration interval which maximizes the performance of TR-ED. The results show that TR technique, by reducing the integration interval, considerably improves the performance compared to the conventional ED scheme.     

Geochemical and Mineralogical Characterization of a Pyritic Waste Pile at the Anjir Tangeh Coal Washing Plant, Zirab, Northern Iran

Coal washing at the Anjir Tangeh plant, in Zirab, northern Iran, has produced more than 1.5 Mt of coal wastes. These waste materials were geochemically and mineralogically characterised to guide development of an appropriate remediation scheme. Three vertical trenches up to 4 m deep were excavated from the coal waste pile surface and 25 solid samples were collected at 0.5 m intervals. The samples were analysed for total concentrations of 54 elements, paste pH, SO ₄ ^?2 , CO ₃ ^?2 , and HCO₃ ^?. The lowest pH values were measured at a depth of 0.3 m. The upper portion (1 m) of one profile was moderately oxidised, while oxidation in the other two profiles did not extend more than 0.8 and 0.5 m beneath the pile surface. The waste piles have low acid-producing potential (15–21.87 kg CaCO₃/t) and high values of acid-neutralizing potential (0.06–96.2 kg CaCO₃/t). Fe, Al, S, Na, Mn, Pb, Zn, Cd, and Ag increased with increasing depth, while Mo, Sr, Zr, and Ni decreased with increasing depth. The results show pyrite oxidation at depth and subsequent leaching of the oxidation products. Mn, Zn, Cu, Pb, Ag, and Cd are the most important contaminants of concern at this site.     

Precoder Design for BICM-MIMO Systems Under Channel Estimation Error

If properly designed, the use of a linear precoder can achieve the maximum coding gain and diversity order in bit-interleaved coded modulation with multiple-input multiple-output systems. However, such maximum coding gain and diversity order are compromised under the practical scenario of having imperfect channel state information (CSI) at the receiver. To alleviate the impact of imperfect CSI on the coding gain and diversity order, joint linear precoder and training pattern are designed in this paper. The design is carried out by considering both the pairwise error probability and the mean square error of the channel estimator. The effectiveness of the proposed design is illustrated by comparing its performance with the performance obtained when only the training pattern is designed for an precoder optimized under the perfect CSI. In particular, simulation results show that a $1.5$ 1.5 dB gain is achieved by the proposed design.     

Effects of Annealing on the Fabrication of Al-TiAl3 Nanocomposites Before and After Accumulative Roll Bonding and Evaluation of Strengthening Mechanisms

The strengthening mechanisms of Al-TiAl₃ nanocomposite, fabricated using cold roll bonding, annealing, and accumulative roll bonding (ARB) on Al sheets sandwiching with pure Ti powder were investigated in the present study. With annealing at 590 ℃ for 2 h, TiAl₃ intermetallic compound was formed. After subsequent ARB process up to 5 cycles, final composite consists of ultrafine Al grains of less than 500 nm with TiAl₃ particles larger than 200 nm. The strength and hardness of the final composite are 2.5 and 3.5 times the initial values, with an ultimate tensile strength of 400 MPa, which is dominated by grain-boundary strengthening due to the ultrafine Al grains, and Orowan strengthening due to the small TiAl₃ particles. For comparison, an alternative fabrication route of cold roll bonding-ARB-annealing was also studied. This study showed that annealing before ARB is a critical factor in producing an ultrafine grain structure containing TiAl₃ particles.     

Guidelines for a Polycentric Region to Reduce Vehicle Use and Increase Walking and Transit Use

Abstract

Problem, research strategy, and findings: The monocentric development pattern in the Alonso–Mills–Muth model underpinned theoretical discussions of urban form in the 1960s and 1970s and truly dominated theory up to the point when Joel Garreau published Edge City: Life on the New Frontier in the early 1990s. Monocentric development patterns remain dominant to this day among smaller metropolitan areas in the United States. However, for larger metropolitan areas in the United States, regional transportation plans suggest a paradigm shift to a polycentric structure. We review 126 regional transportation plans in the United States and find that a hierarchy of centers connected by high-quality transit has become the dominant vision for most of them. The plan for Salt Lake City (UT), for example, strives for a multicentered region even though secondary centers are only beginning to emerge beyond a dominant downtown. Generally missing from regional transportation plans are quantitative criteria for designating and guiding centers: In no case are the quantitative criteria empirically based on proven transportation benefits. Here we investigate how the built environment characteristics of centers are associated with people’s travel mode choices and vehicle use. We employ visual and exploratory approaches through a generalized additive model (GAM) to identify nonlinear relationships between travel outcomes and “D” variables (density, diversity, design, destination accessibility, and distance to transit) within centers. The model and plots help us recommend the built environment characteristics of centers.

Takeaway for practice: The built environment thresholds and relevant tools provided here can enable planners to make informed decisions about future growth patterns, set realistic—yet visionary—goals, and improve the overall health of its residents and communities. We provide strategies and tools that planning agencies, such as metropolitan planning organizations, transit agencies, and municipalities, can adopt to channel developments into centers.     

Antioxidative and synergistic effects of bene kernel and hull oils during oxidation of virgin olive oil

Total amounts of conjugated diene hydroperoxides and carbonyl compounds of a virgin olive oil (VOO) and its purified form as affected by 0.1–6% w/w bene kernel (BKO) and hull (BHO) oils were monitored during 16 h heating at 180°C. The VOO was more prone to the production of off‐flavour carbonyl compounds than to the formation of conjugated diene hydroperoxides. The VOOs oxidative stability decreased significantly due to the removal of the indigenous antioxidative compounds. Oxidative stability, especially regarding the secondary oxidation, significantly improved with increasing concentrations of the BKO than with those of the BHO.