Inventory lot-sizing with supplier selection using hybrid intelligent algorithm

In supply chain management (SCM), multi-product and multi-period models are usually used to select the suppliers. In the real world of SCM, however, there are normally several echelons which need to be integrated into inventory management. This paper presents a hybrid intelligent algorithm, based on the push SCM, which uses a fuzzy neural network and a genetic algorithm to forecast the rate of demand, determine the material planning and select the optimal supplier. We test the proposed algorithm in a case study conducted in Iran.     

Internetworking topologies for local area networks: Pros and cons

This paper deals with internetworking aspects of local area networks (LANs) with other local area networks and/or long-haul networks. Two types of LAN topologies are considered: bus and ring. Internetworking topologies discussed in this paper include, (i) networking of ring LANs via a bus LAN, (ii) networking of ring LANs via a ring LAN, (iii) networking of bus LANs via a bus and (iv) networking of LANs to long-haul networks. Advantages and disadvantages of these topologies are discussed in terms of their performance and other features.     

Sulfonated polyaniline–titanium dioxide nanocomposites synthesized by one-pot UV-curable polymerization method

Sulfonated polyaniline–titanium dioxide (SPAni–TiO₂) hybrid composites have been synthesized by using a new strategy in one-pot system of UV-cured polymerization method. Aqueous solution of aniline and orthoanilinic acid comonomers, a free-radical oxidant and titania precursor were irradiated by UV rays. Hydrolysis and reprecipitation of the titania precursor in aqueous aniline and orthoanilic acid lead to the formation of titanium dioxide particles which in turn catalyze oxidation of comonomers to sulfonated polyaniline. The resultant SPAni–TiO₂ composites were characterized by using different spectroscopy analyses like X-ray diffraction, UV–visible (UV–vis) and infrared spectroscopy. The UV–vis absorption bands revealed that SPAni–TiO₂ nanocomposites are optically active and the blue-shifted peaks due to the presence of titania within the SPAni matrix. Scanning electron microscopy and transmission electron microscopy of the nanocomposite showed a uniform size distribution with spherical and granular morphology. Thermogravimetric analysis revealed that the SPAni–TiO₂ composites have a good thermal stability than the pristine SPAni.     

Low end‐to‐end delay fuzzy networking protocol for mobile wireless sensing

Because of the practical limitations of the energy and processing capabilities, the deployment of many Wireless Sensor Networks (WSN) is facing two main challenges of increasing network lifetime and reducing End to End Delay (EED) which become critical when the nodes are mobile and use non‐rechargeable energy sources. One way to help to extend network lifetime is using fuzzy logic in a form of artificial intelligence. To this end we propose a new routing protocol for using mobile WSNs, which holds the nodes in an equal level of energy and decreases energy dissipation of the network. An optimum path is selected based on the cost of each node to increase network lifetime. In order to lessen EED, we also attempt to design a novel zoning‐scheme for the network area. In this scheme, zonation is dynamic and works based on the Data Link (DL) position. The simulation result shows a significant improvement in lifetime and EED by proposed protocol compared with existing protocols. Copyright © 2016 John Wiley & Sons, Ltd.     

Polylactic Acid in Medicine

Polylactic acid (PLA) is a biodegradable polymer with exceptional properties that has been studied extensively for the past 25 years. The possibility of using devices in human body with minimum inflammation and infection to allow natural healing has obliged researchers to search for biocompatible and biodegradable alternatives. Polylactic acid is one of the most promising biopolymers used in world today. Due to its organic source, it has attracted many attentions. This review presents information about the properties, monomer types, kinetics and different synthesis methods that are currently employed for production of polylactic acid as well as its biomedical and clinical applications in scaffolds, drug delivery systems, bone fixation devices such as screw and plates, surgical suture and meshes.     

Novel nanocomposites obtained by dispersion of LDH modified with N‐tetrabromophthaloyl‐glutamic in poly(amide‐imide) having N‐trimellitylimido‐l‐leucine and 4,4′‐diaminodiphenylether units

Layered double hydroxides (LDHs) have attracted much attention as nanofillers in polymer nanocomposites (NCs) due to their particular surface structural, positively charged layer and so on. In this study, a chiral diacid was synthesized by the reaction of tetrabromophthalic anhydride and glutamic acid. LDH was modified by co‐precipitation of aluminum nitrate, magnesium nitrate, and glutamic acid containing diacid. Chiral poly(amide‐imide) (PAI) was synthesized by direct polycondensation reaction of N‐trimellitylimido‐l ‐leucine and 4,4′‐diaminodiphenylether. Different NCs of the obtained modified LDHs and the chiral PAI were prepared in a short time using ultrasonic technique. The morphology and the structure of the obtained samples were characterized by Fourier transform infrared, thermogravimetric analysis (TGA), field emission scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction analysis. TGA of the NCs showed a special order in thermal stability in compression with the neat PAI owing to the uniform distribution of the nanofillers. POLYM. COMPOS., 37:1323–1329, 2016. © 2014 Society of Plastics Engineers     

Multicarrier constant envelope OFDM signal design for radar applications

Orthogonal frequency division multiplexing (OFDM) radar signals have been introduced for high range resolution radars. These signals have prominent properties such as favorable ambiguity function, high bandwidth efficiency, and possibility of use in dual mode radar/communication systems. But the large amplitude fluctuations of the OFDM signal make it susceptible to system nonlinearities. To alleviate this problem, constant envelope OFDM (CE-OFDM) signal has been introduced which combines orthogonal frequency division multiplexing and phase modulation or frequency modulation. Although several works have been reported on OFDM radar signal design, there is no a systematic approach for designing CE-OFDM signals for radar applications. In this paper we will focus on CE-OFDM signal design for radar applications. Two different methods for designing a CE-OFDM signal with favorable ambiguity functions are introduced. The first one is based on modulating a complementary set of sequences on different sub-carriers while the second is based on using a proper single carrier coded signal and then extracting its most similar multicarrier OFDM or CE-OFDM coded signal.     

Thermal and mechanical properties of polyurethane rigid foam/modified nanosilica composite

Surface modification of fumed nanosilica was performed by using n‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane as a coupling agent. Then, modified nanosilica was utilized in the preparation of polyurethane rigid foam. The characterization and the study of properties were done by some techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, dynamic mechanical analysis, and thermomechanical analysis. Also, tensile test was examined to evaluate the static mechanical properties. With the increasing of modified nanosilica, thermal and static mechanical properties were enhanced, but dynamic mechanical behavior was different from static mechanical behavior because of the different properties of interfacial domain and bulk matrix. The presence of functional groups on the nanosilica surface affected stoichiometry and reduced hard phase formation in bulk polymer. The decrease in glass transition temperature (T_g) confirmed this statement. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

The effect of sodium dodecyl sulfate on mean drop size in a horizontal mixer–settler extractor

The effects of surfactant concentration, impeller speed, and holdup on mean drop diameter, D₃₂, during emulsification have been studied in a mixer–settler. Two well‐defined regions for the dependence of D₃₂ on surfactant concentration were observed. At low surfactant concentrations, D₃₂ decreased significantly with an increase in surfactant concentration, whereas D₃₂ did not depend on surfactant concentration at high surfactant concentrations. The decreasing rate of change of D₃₂ with impeller speed and the increasing rate of change of D₃₂ with holdup both decreased when a surfactant was added to the system. Moreover, an empirical correlation has been derived to predict D₃₂.