State-space ARIMA for supply-chain forecasting

ARIMA is seldom used in supply chains in practice. There are several reasons, not the least of which is the small sample size of available data, which restricts the usage of the model. Keeping in mind this restriction, we discuss in this paper a state-space ARIMA model with a single source of error and show how it can be efficiently used in the supply-chain context, especially in cases when only two seasonal cycles of data are available. We propose a new order selection algorithm for the model and compare its performance with the conventional ARIMA on real data. We show that the proposed model performs well in terms of both accuracy and computational time in comparison with other ARIMA implementations, which makes it efficient in the supply-chain context.     

Production of hydrogen over bimetallic Pt–Ni/δ-Al2O3: I. Indirect partial oxidation of propane

Indirect partial oxidation (IPOX) of propane was studied over bimetallic 0.2 wt.% Pt–15 wt.% Ni/δ-Al₂O₃ catalyst in the 623–743 K temperature range. The unreduced and reduced forms of the catalyst were characterized by ESEM–EDAX and X-ray diffraction (XRD). In the IPOX tests, the effects of steam to carbon ratio (S/C), carbon to oxygen ratio (C/O₂) and residence time (W/F (g_cat h/mol HC)) on the hydrogen production activity, selectivity and product distribution were studied in detail. The effect of temperature program applied (increasing from 623 to 743 K, ITP; decreasing from 743 to 623 K, DTP) during reaction was also tested. The results showed that the Pt–Ni bimetallic system has superior performance characteristics compared to the monometallic catalysts reported in literature. The reason is thought to be the utilization of the catalyst particles as micro heat exchangers during IPOX; the heat generated by Pt sites during exothermic total oxidation (TOX) being readily transferred through the catalyst particles acting as micro heat exchangers to the Ni sites, which promote endothermic steam reforming (SR). The optimal conditions were found as S/C = 3, C/O₂ = 2.70 and W/F = 0.51 g_cat h/mol HC for IPOX of propane on the basis of high hydrogen productivity and selectivity between 623 and 748 K for the experimental conditions tested. The thermo-neutral points obtained showed the sustainability of reaction in terms of energy.     

Mechanical and viscoelastic properties of polyethylene-based microfibrillated composites from 100% recycled resources

In this study, recycled polyethylene (rPE) based microfibrillated composites (MFCs) were developed while incorporating recycled poly(ethylene terephthalate) (rPET) and recycled polyamide 6 (rPA) as the reinforcing fibrillar phases at a given weight ratio of 80 wt% (rPE)/20 wt% (rPET or rPA). The blends were first melt processed using a twin-screw extruder. The extrudates were then cold stretched at a drawing ratio of 2.5 to form rPET and rPA fibrillar structures. Next, the pelletized drawn samples were injection molded at the barrel temperatures below the melting temperatures of rPET and rPA. The tensile, three-point bending, impact strength, dynamic thermomechanical, and rheological properties of the fabricated MFCs were analyzed. The effects of injection molding barrel temperature (i.e., 150°C and 190°C) and extrusion melt processing temperature (i.e., 250°C and 275°C) on the generated fibrillar structure and the resultant properties were explored. A strong correlation between the fibrillar morphology and the mechanical properties with the extrusion and injection molding temperatures was observed. Moreover, the ethylene/n-butyl acrylate/glycidyl methacrylate (EnBAGMA) terpolymer and maleic anhydride grafted PE (MAH-g-PE) were, respectively, melt processed with rPE/rPET and rPE/rPA6 blends as compatibilizers. The compatibilizers refined the fibrillar structure and remarkably influenced mechanical properties, specifically the impact strength.     

Extending the information delivery manual approach to identify information requirements for performance analysis of HVAC systems

Heating, Ventilation and Air-Conditioning (HVAC) systems account for more than 15% of the total energy consumption in the US. In order to improve the energy efficiency of HVAC systems, researchers have developed hundreds of algorithms to automatically analyze their performance. However, the complex information, such as configurations of HVAC systems, layouts and materials of building elements and dynamic data from the control systems, required by these algorithms inhibits the process of deploying them in real-world facilities. To address this challenge, we envision a framework that automatically integrates the required information items and provides them to the performance analysis algorithms for HVAC systems. This paper presents an approach to identify and document the information requirements from the publications that describe these algorithms. We extend the Information Delivery Manual (IDM) approach so that the identified information requirements can be mapped to multiple information sources that use various formats and schemas. This paper presents the extensions to the IDM approach and the results of using it to identify information requirements for performance analysis algorithms of HVAC systems.     

The electrical and dielectric characterization of the Co/ZnO-Rods/p-Si heterostructure depending on the frequency

Journal of Materials Science: Materials in Electronics - Zinc oxide (ZnO) rods film was fabricated by homemade and simple spray pyrolysis technique on a p-type silicon (Si) substrate, and the film...     

Different approaches to synthesize carnosine selective imprinted polymers

Selective recognition of proteins by synthetic molecularly imprinted polymers is one of the interesting topics in biosciences. Carnosine (β-alanyl-l-histidine) and related histidine containing peptides are distributed in a wide range of tissues in vertebrate organisms. These peptides have been extensively studied because of their important physiological properties besides their metal chelation property. In this study, preparation of carnosine specific imprinted polymers (MIPs) for the recognition of imidazole containing peptides with and without copper ion is reported. Carnosine and copper–carnosine complex were employed as template molecules where 4-vinylpyridine and ethylenglycol dimethacrylate were chosen as monomer and crosslinker, respectively. The selectivity and binding studies of copper–carnosine imprinted polymer showed high selectivity toward both carnosine (template peptide) and the cupric ion. The selectivity of copper–carnosine imprinted polymer was 65% and carnosine imprinted polymer was approximately 40%. These results indicate that specific recognition of carnosine is depending on the basis of metal coordination     

Catalytic effect of potassium carbonate on carbothermic production of hexagonal boron nitride

Effect of potassium carbonate addition on the carbothermic formation of hexagonal boron nitride (hBN) was investigated by keeping the K₂CO₃ added B₂O₃+C mixtures in nitrogen atmosphere at 1400 °C for 40–160 min. K₂CO₃ amount was varied in the range of 10–60 wt% of the B₂O₃+C mixture. Products were subjected to XRD and quantitative analyses, SEM and TEM observations, and particle size measurement. Amount of hBN increased considerably with K₂CO₃ addition; also particle size and crystallinity improved. Catalytic role of K₂CO₃ was suggested as forming a potassium borate melt in which hBN particles form, in addition to carbothermic formation reaction. Effect of K₂CO₃ on increasing the hBN amount decreased when it was used over 40%. This was attributed to the rapid evaporation of the formed potassium borate liquid.     

Effects of Variety,Maturation and Growing Region on Chemical Properties,Fatty Acid and Sterol Compositions of Virgin Olive Oils

Chemical properties, fatty acid and sterol compositions of olive oils extracted from Gemlik and Halhal? varieties grown in Hatay and Mardin provinces in Turkey were investigated during four maturation stages. The olive oil samples were analyzed for their chemical properties such as free acidity, peroxide value, total carotenoid, total chlorophyll, total phenolic contents, antioxidant activity, fatty acid and sterol compositions. Chemical properties, fatty acids and sterol profiles of olive oil samples generally showed statistically significant differences depending on the varieties, maturation and growing areas (p < 0.05). As free fatty acid contents and total phenolic contents increased, total carotenoid and chlorophyll contents decreased throughout the maturity stages. Total carotenoid and chlorophyll contents of oil samples from Mardin were higher than those of Hatay. The total phenolic compounds of olive oil samples ranged from 20.62 in Gemlik to 525.22 mg GAE/kg oil in Halhal? from Hatay. In general, the phenolic contents and antioxidant activities of olive oil samples were positively associated. Oleic acid content was the highest 71.53 % in H1 samples in Hatay. Total sterol contents were 1194.33 mg/kg in Halhal? and 2008.66 mg/kg in Gemlik from Hatay. Stigmasterol contents of oils obtained from Hatay were lower than those of Mardin. Oleic acid, palmitic acid, β‐sitosterol, ?‐5‐avenasterol and campesterol contents fluctuated with maturation for each of variety from both growing regions. These results showed that the variety, growing area and maturation influence the chemical properties, fatty acid and sterol compositions.