Synthesis and properties of polyurethane networks derived from new soybean oil‐based polyol and a bulky blocked polyisocyanate

BACKGROUND: Developing vegetable oil‐based polyols for polyurethane manufacturing is becoming highly desirable for both economic and environmental reasons. Most vegetable oils do not bear hydroxyls naturally. The objective of this work was to prepare a new soybean oil‐based polyol with high functionality of hydroxyl groups and built‐in (preformed) urethane bonds. RESULTS: A facile and improved method was developed for the transformation of epoxidized soybean oil into carbonated soybean oil under ambient pressure of CO₂ gas, with tetrabutylammonium bromide/calcium chloride as catalyst/co‐catalyst couple. Ring‐opening reaction of the carbonated oil with ethanolamine led to the desired polyol. A one‐pack polyurethane system was prepared via combination of the polyol and a blocked polyisocyanate. The polyol and final polyurethanes were fully characterized, and their physical, mechanical, viscoelastic and electrical insulating properties were studied. CONCLUSION: The application of this newly developed soybean oil‐based polyol for preparation of electroinsulating casting polyurethanes was examined. The prepared soy‐based polyurethanes offered excellent thermal and electrical insulating properties. Also, tunable physical and chemical properties for the final polyurethanes were achieved by replacing part of the soybean oil‐based polyol with poly(propylene glycol) (M_n = 1000 g mol^?1). Copyright © 2008 Society of Chemical Industry     

Integrated Inventory Control and Facility Location Decisions in a Multi-Echelon Supply Chain Network with Hubs

This paper develops mathematical models to coordinate facility location and inventory control for a four-echelon supply chain network consisting of multiple suppliers, warehouses, hubs and retailers. The hubs help in reducing transportation costs by consolidating products from multiple warehouses and directing the larger shipments to the retailer. The integrated models studied in this paper simultaneously determines three types of decisions: (i) facility location—the number and location of warehouses and hubs, (ii) allocation—assignment of suppliers to located warehouses and retailers to located warehouses via the location hubs, and (iii) inventory control decisions at each located warehouse. The goal is to minimize the facility location, transportation and the inventory costs. A mixed integer nonlinear programming formulation is first presented. The nonlinear integer programming formulation is then transformed into a conic mixed integer program and a novel and compact conic mixed integer programming formulation. Computational runs are conducted using commercial solvers to compare the performance of the different formulations. The compact conic mixed integer programming formulation was found to significantly outperform the other formulations by achieving significant computational savings. The results demonstrate that large scale instances of certain multi-echelon supply chain network design problems can be solved using commercial solvers through intelligent reformulation of the model.     

Modeling of ferrofluid magnetic actuation with dynamic magnetic fields in small channels

One of the most important and promising research areas in biomedical and micropumping applications is magnetic actuation of ferrofluids with dynamic magnetic fields. For ensuring the use of ferrofluids in various applications in engineering fields, their flows generated by magnetic fields should be extensively investigated and simulated. In this study, simulations of ferrofluid actuation with dynamic magnetic fields were performed by modeling it using the COMSOL Multiphysics software, and iron oxide nanoparticle-based ferrofluids at different angles of rotating magnets were considered to provide insight into ferrofluid flow in small channels. Ferrofluid flows were modeled at different magnetic flux densities provided by rotating magnets, and velocity profiles inside the channel were analyzed. It was shown that ferrofluid actuation can be considered as a futuristic micropumping alternative, simulation results matched well with the experimental results of previous work, and the established model could serve as a tool to analyze ferrofluid flows generated by dynamic magnetic fields. The results of the model show that flow rates up to 100 µl/s can be reached at a rotation angle of 30° by using dynamic magnetic fields. Various applications including biomedical applications might be envisaged.     

Optimizing the choice of influential nodes for diffusion on a social network

An optimization approach is taken to locating the optimal set of initial contacts in a social network to maximize the number of total network members reached by a message. It is assumed that initial contacts are costly and that the number of initial contacts must be minimized simultaneously with maximizing the total number of network members contacted. A bi‐objective probabilistic integer programming model is developed that assumes that actors are heterogeneous in the probability that they will pass messages along their ego networks. Considering the complexity of solving the proposed model, it reformulated as a pure integer programming model. The algorithm is illustrated by the analysis of message passing in a short‐message system (texting) among university students. Copyright © 2015 John Wiley & Sons, Ltd.     

Control and Data Channel Resource Allocation in OFDMA Heterogeneous Networks

This paper investigates the downlink resource allocation problem in Orthogonal Frequency Division Multiple Access (OFDMA) Heterogeneous Networks (HetNets) consisting of macro cells and small cells sharing the same frequency band. Dense deployment of small cells overlaid by a macro layer is considered to be one of the most promising solutions for providing hotspot coverage in future 5G networks. The focus is to devise an optimised policy for small cells’ access to the shared spectrum, in terms of their transmissions, in order to keep small cell served users sum data rate at high levels while ensuring that certain level of quality of service (QoS) for the macro cell users in the vicinity of small cells is provided. Both data and control channel constraints are considered, to ensure that not only the macro cell users’ data rate demands are met, but also a certain level of Bit Error Rate (BER) is ensured for the control channel information. Control channel reliability is especially important as it holds key information to successfully decode the data channel. The problem is addressed by our proposed linear binary integer programming heuristic algorithm which maximises the small cells utility while ensuring the macro users imposed constraints. To further reduce the computational complexity, we propose a progressive interference aware low complexity heuristic solution. Discussion is also presented for the implementation possibility of our proposed algorithms in a practical network. The performance of both the proposed algorithms is compared with the conventional Reuse-1 scheme under different fading conditions and small cell loads. Results show a negligible drop in small cell performance for our proposed schemes, as a trade-off for ensuring all macro users data rate demands, while Reuse-1 scheme can even lead up to 40 % outage when control region of the small cells in heavily loaded.     

A Computational Algorithm to Produce Virtual X-ray and Electron Diffraction Patterns from Atomistic Simulations

Electron and x-ray diffraction are well-established experimental methods used to explore the atomic scale structure of materials. In this work, a computational algorithm is developed to produce virtual electron and x-ray diffraction patterns directly from atomistic simulations. This algorithm advances beyond previous virtual diffraction methods by using a high-resolution mesh of reciprocal space that eliminates the need for a priori knowledge of the crystal structure being modeled or other assumptions concerning the diffraction conditions. At each point on the reciprocal space mesh, the diffraction intensity is computed via explicit computation of the structure factor equation. To construct virtual selected-area electron diffraction patterns, a hemispherical slice of the reciprocal lattice mesh lying on the surface of the Ewald sphere is isolated and viewed along a specified zone axis. X-ray diffraction line profiles are created by binning the intensity of each reciprocal lattice point by its associated scattering angle, effectively mimicking powder diffraction conditions. The virtual diffraction algorithm is sufficiently generic to be applied to atomistic simulations of any atomic species. In this article, the capability and versatility of the virtual diffraction algorithm is exhibited by presenting findings from atomistic simulations of 〈100〉 symmetric tilt Ni grain boundaries, nanocrystalline Cu models, and a heterogeneous interface formed between α-Al₂O₃ (0001) and γ-Al₂O₃ (111).     

Neural Network Solution for Forward Kinematics Problem of Cable Robots

Forward kinematics problem of cable robots is very difficult to solve the same as that of parallel robots and in the contrary to the serial manipulators’. This problem is almost impossible to solve analytically because of the nonlinearity and complexity of the robot’s kinematic equations. Numerical methods are the most common solutions for this problem of the parallel and cable robots. But, convergency of these methods is the drawback of using them. In this paper, neural network approach is used to solve the forward kinematics problem of an exemplary 3D cable robot. This problem is solved in the typical workspace of the robot. The neural network used in this paper is of the MLP type and a back propagation procedure is utilized to train the network. A simulation study is performed and the results show the advantages of this method in enhancement of convergency together with very small modeling errors.     

High-level evidences in endodontics

Number of published medical/dental articles is growing at an exponential rate; this makes it difficult to collect all these resources and provide an organized and valuable/useful document. Systematic reviews and meta-analyses as high-level evidences are considered remedies for this concern. Continuous alterations in all fields of dental sciences necessitate the more of such high-level evidences. This study aimed on the quantity of endodontic systematic reviews and meta-analyses so far. This study began with targeted electronic searches of PubMed, and Cochrane library databases about the present systematic review and meta-analysis articles in endodontics within 2001–Jan 2012. Overall, 49 studies were systematic review and meta-analysis, the first comprised 34 articles and the latter contained seven articles; the remained eight studies had utilized both of them. Performing a topic sorting, 22 articles were about materials and techniques, 12 about pre- and post-treatment considerations, four about single/multiple visits, six with perio-prostho themes, and the five remained were of other topics. Limited number of 49 high-level evidences does not meet the expectation from endodontics as a boundless and progressive field of science. Therefore, more comprehensive and all-inclusive studies of systematic reviews and meta-analyses are compulsory in endodontics. The more the scientific-based endodontic practice, the more the high-level evidence based publications with good systematic reviews and favorable meta-analysis.     

Cumin seed meal with enzyme and polyethylene glycol as an alternative to wheat bran in broiler diets

Iran produces about 7000 metric tons of cumin seed meal (CSM) as a by‐product of cumin oil extraction factories, annually. To evaluate the nutritional significance of cumin seed meal as a broiler feedstuff, an experiment was conducted using 288 male broiler chicks (14 days old) receiving diets containing 0, 25 and 50 g kg⁻¹ of CSM with and without polyethylene glycol (PEG) and enzyme (Grindazyme^™ GP 15000) for 28 days. Total body weight (BW), body weight gain (WG), feed intake (FI), feed conversion ratio (FCR), weight of carcass and percentage of legs, breast and edible parts of carcass were measured. The results showed that, inclusion of CSM in broiler diets had no negative influence on parameters evaluated compared to the control diet containing wheat bran (P > 0.05). PEG and enzyme had no influence on the bird performance (P > 0.05). There was an increase in relative weight of gizzard when the amount of CSM in the diet was increased (P < 0.01). An increase in relative weight of gizzard in birds that received the CSM diet was likely to be due to the increase in fibre content of CSM diets. In respect of the low price of CSM, it could be concluded that inclusion of CSM at levels used in this experiment has no negative effect on broiler performance and reduces the overall cost of broiler production. Copyright © 2006 Society of Chemical Industry     

Cumin seed meal as an alternative to wheat bran in commercial laying hen diets

To evaluate the nutritional significance of cumin seed meal (CSM) as a commercial poultry feedstuff on laying hen performance and quality of laid eggs, an experiment was conducted using 144 (48‐week‐old) laying hens receiving diets containing 0, 25 and 50 g CSM kg^?1 with or without polyethylene glycol (PEG 6000) and xylanase enzyme (Grindazym^? GP 15000) for 9 weeks. Body weight on the first and last days of the experiment and daily egg production and egg weight and weekly feed intake during the first, fifth and ninth weeks of the experiment were recorded. Shell weight, shell thickness, Haugh unit and yolk colour were measured during the last week of the experiment. The results showed that inclusion of CSM in laying hen diets had no negative influence on the parameters measured compared with the control diet (P > 0.05), but enhanced egg yolk colour (P < 0.05). PEG increased the daily feed intake of birds receiving CSM diets (P < 0.01) and tended to enhance daily egg production and egg weight, although not significantly. Grindazym decreased shell weight and thickness of laid eggs (P < 0.05) and tended to increase hen body weight, but had no influence on other parameters measured. The results demonstrated that CSM can be substituted for wheat bran in layer diets at 25 or 50 g kg^?1 dietary inclusion level without any adverse effect on hen performance or egg quality, and might enhance egg yolk colour. In view of the low price of CSM, it could be concluded that inclusion of CSM in the diet might be beneficial to the commercial laying hen industry and reduce the overall cost of egg production. Copyright © 2006 Society of Chemical Industry