bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of bubble‐size distribution in water and freon co‐blown free rise polyurethane foams
Authors: Niyogi Debdarsan , Kumar Rajinder , Gandhi Kandukuri S. 
Published: April 2014

ABSTRACTA model has been developed to simulate the foam characteristics obtained, when chemical (water) and physical (Freon) blowing agents are used together for the formation of polyurethane foams. The model considers the rate of reaction, the consequent rise in temperature of the reaction mixture, nucleation of bubbles, and mass transfer of CO2 and Freon to them till the time of gelation. The model is able to explain the experimental results available in literature. It further predicts that the nucleation period gets reduced with increase in water (at constant Freon content), whereas with increase in Freon (at constant water) concentration nucleation period decreases marginally leading to narrower bubble‐size distribution. By the use of uniform sized nuclei added initially, the model predicts that the bubble‐size distribution can be made independent of the rate of homogeneous nucleation and can, thus, offer an extra parameter for its control. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40745.
MgCl2‐supported TiCl4catalysts containing diethyl norbornene‐2,3‐dicarboxylate internal electron donor for 1‐butene polymerization: Effects of internal electron donor configuration
Authors: Dong Xiaofang , Zhang Li , Liu Zhibo , Yang Min , Duan Zhongyu , Hou Kaihu , Liu Binyuan , Kim IL 
Published: April 2014

ABSTRACTThree isomeric 5‐norbornene‐2,3‐dicarboxylic acid diethyl ester (NDDE) withendo‐,exo‐, andtrans‐configuration have been synthesized and employed as internal electron donors (IED) in 1‐butene polymerization over magnesium chloride supported Ziegler–Natta catalysts. It was found that the configuration of NDDE plays a key role in tuning the catalyst activity, stereospecificity, molecular weight (MW), and polydispersity index (PDI) of resulting poly(1‐butene). The type of catalyst withcis‐5‐norbornene‐endo‐2,3‐dicarboxylic acid diethyl ester as IED shows the highest catalyst activity, while catalyst withtrans‐NDDE as IED yields the poly(1‐butene) with the highest MW and the most broad PDI. IR results showed that the NDDE withendo‐,exo‐, andtrans‐configuration have different coordination way to MgCl2, subsequently affecting the catalysts performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2014,131, 40758.
Improved hemocompatibility of silk fibroin fabric using layer‐by‐layer polyelectrolyte deposition and heparin immobilization
Authors: Elahi M. Fazley , Guan Guoping , Wang Lu , King Martin W. 
Published: April 2014

ABSTRACTSilk fibroin has long been used as implantable surgical sutures and it has acceptable mechanical properties and patency rates in animal models and in clinical end‐uses. However, fibroin has been shown to be hemolytic and can cause damage to red blood cells. So to be used as an implantable vascular prosthesis its hemocompatibility needs to be improved. This study has taken two sequential steps to address this problem. First, to create a positively charged layer on the fibroin fibers' surface, a 1.5 and 2.5 bilayers polyelectrolyte surface deposition layer‐by‐layer technique was used with the positive counterion poly(allylamine hydrochloride) and the negative counterion poly(acrylic acid). Second, negatively charged low molecular weight heparin was then immobilized on these positively charged self‐assembled surfaces. The presence of the heparin was confirmed with Alcian Blue staining and a toluidine blue assay, and the increased roughness and hydrophilicity of the modified surfaces were characterized by scanning electron microscopy, contact angle measurements, and atomic force microscopy. In addition, a negligible hemolytic effect, reduced protein adsorption, and a higher concentration of free hemoglobin measured by a kinetic clotting time test were found to be enhanced with the use of 2.5 bilayers compared to the 1.5 bilayers self‐assembly technique. Given the success of these preliminary results, it is anticipated that this novel approach of surface modification and heparin immobilization will demonstrate long‐term patency during future animal trials of small caliber silk fibroin vascular grafts. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40772.
Crystallization and thermal properties of biodegradable polyurethanes based on poly[(R)‐3‐hydroxybutyrate] and their composites with chitin whiskers
Authors: Saad Gamal R. , Salama Hend E. , Mohamed Nadia A. , Sabaa Magdy W. 
Published: April 2014

ABSTRACTA series of biodegradable polyurethanes (PUs) were synthesized from hydroxylated bacterial poly[(R)‐3‐hydroxybutyrate], P[(R)‐HB]‐diol, as crystallizable hard segment and hydroxyl‐terminated synthetic poly[(R,S)‐3‐hydroxybutyrate), P[(R,S)‐HB]‐diol, as an amorphous soft segment, using 1,6‐hexamethylene diisocyanate, as non‐toxic connecting agent. The P[(R)‐HB] content was varied from 30 to 70 wt %. The resulting copolymers were characterized by FT‐IR, 1H‐NMR, DSC, and TGA. The DSC data revealed that the melting of P[(R)‐HB] segment increases with increasing its own content in the PUs. The cold and melt crystallization are enhanced with increasing P[(R)‐HB] content. The TGA data revealed that the thermal decomposition mainly occurred via a single degradation step and the thermal stability slightly increased with increasing P[(R)‐HB] content. The non‐isothermal crystallization behavior of PU sample containing 40 wt % PHB with and without α‐Chitin whiskers was studied using DSC, and their kinetics data were investigated via the Avrami, Ozawa, and Z.S. Mo methods, respectively. Crystallization activation energy was estimated using Kissinger's method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40784.
Digraphs with Distinguishable Dynamics Under the Multi‐Agent Agreement Protocol
Authors: Rahimian Mohammad Amin , Ajorlou Amir , Aghdam Amir G. 
Published: April 2014

AbstractThis work studies the ability to distinguish digraphs from the output response of some observing agents in a multi‐agent network under the agreement protocol. Given a fixed observation point, it is desired to find sufficient graphical conditions under which the failure of a set of edges in the network information flow digraph is distinguishable from another set. When the latter is empty, this corresponds to the detectability of the former link set given the response of the observing agent. In developing the results, a powerful extension of the all‐minors matrix tree theorem in algebraic graph theory is proved which relates the minors of the transformed Laplacian of a directed graph to the number and length of the shortest paths between its vertices. The results reveal an intricate relationship between the ability to distinguish the responses of a healthy and a faulty multi‐agent network and the inter‐nodal paths in their information flow digraphs. The results have direct implications for the operation and design of multi‐agent systems subject to multiple link losses. Simulations and examples are presented to illustrate the analytic findings.
Robust Partially Mode Delay‐Dependent ℋ∞ Output Feedback Control of Discrete‐Time Networked Control Systems
Authors: Chae Seunghwan , Huang Dan , Nguang Sing Kiong 
Published: April 2014

AbstractIn this paper, a methodology for designing an output feedback controller for discrete‐time networked control systems has been considered. More precisely, network‐induced delays between the sensor and the controller is modelled by a Markov chain with transition probabilities which are not assumed to be fully known. The systems parameter uncertainties are assumed to be norm‐bounded and possibly time‐varying. To the best of the authors knowledge, the problem of designing a partially mode delay‐dependent output feedback controller for NCSs with partially known transition probability matrix has not been investigated in the literature. Based on the Lyapunov‐Krasovskii functional approach, sufficient conditions for the existence of a robust partially mode delay‐dependent output feedback controller are given in terms of bilinear matrix inequalities which can be solved using a cone complementarity linearization algorithm. The proposed design methodology differs from the existing design methodologies in that dynamic output feedback controllers are parameterized by both modes and transition probabilities, as opposed to the existing design approaches which parameterize controllers by modes only. The results obtained reduce to the existing results on fully known transition matrices when transition probabilities are fully known. It is shown that the proposed methodology can be applied to real world systems. The proposed design methodology is verified by using a DC servo motor system where the plant and the controller are connected via a cellular network with partially known transition probability matrix.
Intelligent Adaptive Trajectory Tracking Control for an Autonomous Small‐Scale Helicopter Using Fuzzy Basis Function Networks
Authors: Tsai Ching‐Chih , Wang Zen‐Chung , Lee Chi‐Tai , Li Yi‐Yu 
Published: April 2014

AbstractThis paper presents an intelligent adaptive trajectory tracking controller using fuzzy basis function networks (FBFN) for an autonomous small‐scale helicopter. The FNFN is used online to learn the vehicle mass and the coupling effect between the force and the moments, and the intelligent adaptive controller then is synthesized systematically using a backstepping technique. This controller is designed to accomplish the ultimate boundedness of the closed‐loop helicopter dynamics and accommodate agile flight maneuvers. Two nonlinear simulations on hovering and trajectory tracking are conducted to show the effectiveness and merit of the proposed controller, which is also shown to be superior by performance comparison with a well‐known neural‐network controller.
A smartphone‐centric platform for remote health monitoring of heart failure
Authors: Bisio Igor , Lavagetto Fabio , Marchese Mario , Sciarrone Andrea 
Published: April 2014

SummaryHeart failure is a chronic disease that alternates intense and weak phases and requires repeated and frequent hospital treatments. The use of automatic instruments for a remote and ubiquitous monitoring of biological parameters relevant to heart failure pathophysiology offers new perspectives to improve the patients' quality of life and the efficacy of the treatment.The platform described in this paper represents an implementation of an automatic remote monitoring tool where smartphones play a crucial role. They are not employed just to communicate through traditional client‐server applications and they are not only the hub of information sent by sensors, but they also act as intelligent processors and autonomous sensors of the patients' motion through a high‐accuracy activity recognition algorithm. The proposed platform combines the evolution of health systems and the consequent needs of modern telemedicine with the current context‐aware capability of recent smartphones, obtained by implementing specific algorithmic solutions, and with the anything, anytime, and anywhere communication capability of the pervasive communications paradigm. Performance evaluation focuses on the accuracy of the activity recognition estimation, on its applicability to real life, and on the data exchange between smartphones and medical server, allowing to envisage the potential of the designed platform. Copyright © 2014 John Wiley & Sons, Ltd.
An efficient distributed routing protocol for wireless sensor networks with mobile sinks
Authors: Shi Lei , Yao Zheng , Zhang Baoxian , Li Cheng , Ma Jian 
Published: April 2014

SummaryIntroducing mobile sinks into a wireless sensor network can effectively improve the network performance. However, sink mobility can bring excessive protocol overhead for route maintenance and may offset the benefit from using mobile sinks. In this paper, we propose a dynamic layered routing protocol to address this problem. The proposed protocol integrates dynamic layered Voronoi scoping and dynamic anchor selection to effectively reduce the dissemination scopes and frequencies of routing updates as the sinks move in the network. Simulation results show that the proposed protocol can effectively reduce the protocol overhead while ensuring high packet delivery ratio as compared with existing work. Copyright © 2014 John Wiley & Sons, Ltd.
Connection‐Strength Estimation of Neuronal Networks by Fitting for Izhikevich Model
Authors: Isomura Takuya , Takeuchi Akimasa , Shimba Kenta , Kotani Kiyoshi , Jimbo Yasuhiko 
Published: April 2014

SUMMARYRecently, there has been abundant research using multineuron recording, but there are many problems with extracting the features from the obtained spike time series, which are huge in volume and complex. Here we introduce a new method of estimating synaptic connection strengths between neurons by fitting to the Izhikevich model by maximum likelihood estimation. We demonstrate that our method can estimate connection strengths from spike time series given by a simulated neural ensemble and can estimate nonconnectivity between two independent cultured neuronal networks. These results suggest that our method is applicable to network and plasticity analysis of neuronal networks.
Overvoltages on DC Side of Power Conditioning System Caused by Lightning Stroke to Structure Anchoring Photovoltaic Panels
Authors: Yamamoto Kazuo , Takami Jun , Okabe Narimitsu 
Published: April 2014

SUMMARYPhotovoltaic (PV) power plants and wind turbines are eco‐friendly power generators that utilize solar energy and wind energy, respectively. Many large‐scale PV power plants have been constructed using government subsidies. Large‐scale PV power plants are usually constructed in large open spaces that contain some tall structures. Therefore, such large‐scale PV power plants are likely to attract lightning, which may result in the malfunction or breakdown of electrical and electronic equipment. In this investigation, overvoltages generated when a lightning strikes a structure anchoring PV panels were measured using a 1:10 scale model. The measurements were also verified using the finite‐difference time‐domain method. The mechanisms of overvoltage generation on an actual‐scale PV power plant were also clarified.
Enantiopure Conducting Salts of Dimethylbis(ethylenedithio)tetrathiafulvalene (DM‐BEDT‐TTF) with the Hexachlororhenate(IV) Anion
Authors: Pop Flavia , Allain Magali , Auban‐Senzier Pascale , Martínez‐Lillo José , Lloret Francesc , Julve Miguel , Canadell Enric , Avarvari Narcis 
Published: April 2014

AbstractThe enantiopure radical cation salts [(S,S)‐DM‐BEDT‐TTF]4[ReCl6] ([(S,S)‐1]4[ReCl6]) and [(R,R)‐DM‐BEDT‐TTF]4[ReCl6] ([(R,R)‐1]4[ReCl6]) [DM‐BEDT‐TTF = dimethylbis(ethylenedithio)tetrathiafulvalene] have been prepared by electrocrystallization of the chiral precursor DM‐BEDT‐TTF in the presence of NBu4[ReCl5(pyrazine)] (NBu4 = tetra‐n‐butylammonium cation; pyz = pyrazine) as supporting electrolyte. The single‐crystal X‐ray analysis shows that the compounds crystallize in the triclinic system, non‐centrosymmetric space group P1, and that the donors arrange in parallel columns. The four independent donor molecules possess approximate charges of +1, +1/2, +1/2 and 0, according to the structural parameter analysis and band‐structure calculations, which also support the semiconducting behaviour of the materials. The rhenium(IV) ion in both compounds is six‐coordinate with six chloro atoms that describe a slightly distorted octahedral environment with Re–Cl distances that cover the short range 2.348–2.374 Å. Magnetic measurements on polycrystalline samples of [(S,S)‐1]4[ReCl6] and [(R,R)‐1]4[ReCl6] have been investigated in the temperature range 2–295 K. They are practically identical and confirm the presence of high‐spin S = 3/2 [ReCl6]2– isolated monomers together with a Pauli paramagnetism, typical of this kind of system. The magnetic susceptibility data are thoroughly reproduced over the whole temperature range with a simple model of isolated S = 3/2 ions with a zero‐field splitting plus a temperature‐independent paramagnetism (TIP), and the best‐fit parameters being gRe = 1.875(2), |D| = 4.50(3) cm–1 and TIP = 3630(20)×10–6 cm3 mol–1 (2D is the energy gap between the MS = ±3/2 and MS = ±1/2 Kramers doublets).
Synthesis and characterization of novel vinylester prepolymers from cardanol
Authors: Jaillet Fanny , Nouailhas Hélène , Auvergne Rémi , Ratsimihety Amédée , Boutevin Bernard , Caillol Sylvain 
Published: April 2014

A novel thermosetting vinylester (VE) resin was prepared form cardanol, coming from cashew nut shell liquid (CNSL), a renewable resource and waste of the cashew industry. A VE cardanol‐based prepolymer was synthesized by reacting commercial cardanol diepoxy and methacrylic acid. The VE cardanol‐based prepolymer was polymerized by free radical polymerization to yield a thermoset resin with different monomers used as reactive diluents such as styrene (ST), isobornyl methacrylate (IBOMA), dibutyl itaconate (DBI), butanediol dimethacrylate (BDDMA), and hexanediol dimethacrylate (HDDMA). The resulting VE resin was characterized by TGA, DSC, and DMA analyses and compared to diglycidyl ether of bisphenol A (DGEBA)‐based VE resin. Cardanol‐based VE resins exhibit interesting mechanical and thermal properties for composite materials. The Tg value is 86°C with 40% by mass of ST and 116°C with 40% by mass of IBOMA. Around 70°C of Tg are lost compared to DGEBA‐based VE resin, whereas with an oil‐based VE resin the loss of Tg value is around 150°C.Practical application: The acrylated cardanol‐based monomer described in this contribution, that is, acrylated cardanol from CNSL, provided new biobased aromatic building blocks for further free radical polymerizations with various reactive diluents. The obtained VE materials are partially biobased and may be used as binders in composite applications.Biobased vinylester prepolymer (VE) was synthesized by acrylation of commercial di‐epoxy cardanol (Cardolite NC514), coming from CNSL. Vinylester materials were synthesized by free radical polymerization of VE with various monomers. Mechanical and thermal properties of obtained materials showed that synthesized vinylester material could lead to binders for composite application.
Sulfoximine‐Based Modular Enantioselective Synthesis of Azaspirocycles Featuring Sulfoximine Displacement, Dianion Cycloalkylation, RCM and N‐Acyliminium Ion Formation
Authors: Köhler (née Adrien) Adeline , Raabe Gerhard , Runsink Jan , Köhler Franz , Gais Hans‐Joachim 
Published: April 2014

AbstractWe describe a modular, enantioselective synthesis of functionalised azaspirocycles with a range of ring sizes. The synthesis exploits the special features of sulfoximines, including chirality, carbanion‐stabilisation, nucleophilicity, and nucleofugacity. Diastereoselective intramolecular amination of hydroxyalkyl‐substituted cycloalkenylsulfoximines by the carbamate method gave bicyclic oxazinanones containing an amino‐substituted tertiary C atom. Cycloalkylation of the corresponding C,N‐dianions with biselectrophiles afforded sulfoximine‐substituted spirocycles. Monoalkylation of the C,N‐dianions with functionalised electrophiles, having a double bond and acetal group, furnished the corresponding C‐alkylated bicyclic sulfoximines. Displacement of the sulfoximine group of bicyclic and spirocyclic sulfoximines by haloformate reactions gave the corresponding halides (Cl, I). Alkylation of the bicyclic halides with functionalised cuprates and reduction of the sulfoximine‐substituted bicycles, carrying an alkyl group at the Cα atom, gave starting materials for a step‐wise construction of the heterocyclic ring. Ring‐closing metathesis of a bicyclic C,N‐dienyl derivative furnished the corresponding spirocycle with an unsaturated piperidine ring. Cyclisation of an acetal group containing bicyclic oxazinanone gave spirocycles containing O,N‐acetal and enamide groups. The diastereoselective reaction of a spirocyclic O,N‐acetal with an allylsilane furnished the corresponding spirocycle, carrying an allyl group at the C atom adjacent to the N atom. Attempts to lithiate a bicyclic carbamate at the CH2 group adjacent to the N atom were not successful.
Gold‐Catalyzed 5‐endo‐dig Cyclization of 2‐[(2‐Aminophenyl)ethynyl]phenylamine with Ketones for the Synthesis of Spiroindolone and Indolo[3,2‐c]quinolone Scaffolds
Authors: Reddy Basi. V. Subba , Swain Manisha , Reddy S. Madhusudana , Yadav J. S. , Sridhar B. 
Published: April 2014

AbstractA tandem gold‐catalyzed 5‐endo‐dig/spirocyclization of 2‐[(2‐aminophenyl)ethynyl]phenylamines with isatins was achieved to produce the corresponding 5′,11′‐dihydrospiro[indoline‐3,6′‐indolo[3,2‐c]quinolin]‐2‐one derivatives in good yields with high regioselectivity. This reaction proceeded well at ambient temperature under mild conditions. Ketones also participated smoothly under similar conditions to produce 6,6‐disubstituted‐6,11‐dihydro‐5H‐indolo[3,2‐c]quinolones.
Out‐of‐plane stability of buckling‐restrained braces including moment transfer capacity
Authors: Takeuchi Toru , Ozaki Hitoshi , Matsui Ryota , Sutcu Fatih 
Published: April 2014

SUMMARYBuckling‐restrained braces (BRBs) are widely used as ductile seismic‐resistant and energy‐dissipating structural members in seismic regions. Although BRBs are expected to exhibit stable hysteresis under cyclic axial loading, one of the key limit states is global flexural buckling, which can produce an undesirable response. Many prior studies have indicated the possibility of global buckling of a BRB before its core yields owing to connection failure. In this paper, BRB stability concepts are presented, including their bending‐moment transfer capacity at restrainer ends for various connection stiffness values with initial out‐of‐plane drifts, and a unified simple equation set for ensuring BRB stability is proposed. Moreover, a series of cyclic loading tests with initial out‐of‐plane drifts are conducted, and the results are compared with those of the proposed equations. © 2013 The Authors.Earthquake Engineering & Structural Dynamicspublished by John Wiley & Sons Ltd.
Strong motion displacement waveforms using 10‐Hz precise point positioning GPS: an assessment based on free oscillation experiments
Authors: Moschas Fanis , Avallone Antonio , Saltogianni Vasso , Stiros Stathis C. 
Published: April 2014

SUMMARYThe recently developed precise point positioning (PPP) technique permits to compute instantaneous coordinates of a GPS station relatively to distant reference stations and waveforms of ground displacements during strong motions at the 1 Hz level. This is another application of GPS, different from the computation of static coseismic movements or of accurate monitoring of dynamic displacements of structures using a static receiver and a nearby moving receiver (DGPS). Recently, earthquake ground displacement waveforms using 10‐Hz GPS data have also been calculated, but no independent evidence to assess their quality exists. To overcome this problem, we evaluated the output of 10‐Hz PPP results on the basis of supervised learning experiments. Semistatic and dynamic displacements (damped harmonic oscillations) of known characteristics of the order of a few centimeter were produced and were recorded by GPS, an accelerometer, and a robotic total station. Time series of instantaneous displacements were analyzed using different PPP techniques and were compared with reference (true) values derived from DGPS and the other sensors. Our analysis revealed that the PPP‐derived coordinates are contaminated by long‐period noise but they can display the details of semistatic displacements, while their short‐period component describes well the pattern of waveforms and spectra (at least up to 4 Hz) of dynamic displacements, with up to 20 mm accuracy for isolated points. These results indicate that 10‐Hz PPP‐GPS is useful for earthquake engineering and can safely be used to reconstruct waveforms of deflections of the ground and of various points on structures during strong motions. Copyright © 2014 John Wiley & Sons, Ltd.