Probing effects of alternately‐embedded phenoxy phenyl lateral groups on properties of novel aromatic poly(ether‐urea)s

A new class of alternate aromatic poly(ether‐urea)s having bulky phenoxy phenyl lateral groups was prepared by the reaction of 2,2′‐bis[(p‐phenoxy phenyl)]‐4,4′‐diaminodiphenyl ether (PPAPE) with two diisocyanates, isophorone diisocyanate and 2,4‐tolylene diisocyanate. The limited viscosity values as well as M _n and M _w values of the resulting polymers were determined. The resulting poly(ether‐urea)s could be easily cast into optically‐transparent, flexible, and light color films. The cut‐off wavelength values and the percentage of transmittance at 800 nm were found to be at about 415 nm and 85%, respectively. PPAPE‐derived poly(ether‐urea)s showed a low‐crystallinity and had excellent solubility in polar organic solvents. T_onset, T_g, T_d5%, and T_d10% values of the PPAPE‐derived polymers measured from their DSC and TGA thermograms were up to 270, 280, 315, and 340°C, respectively. Surface morphology of the resulted poly(ether‐urea)s were also evaluated by their scanning electron microscopy images. Excellent organo‐solubility, satisfactory film quality, moderate T_g values, and good thermal stability make this class of poly (ether‐urea)s promising high‐performance polymeric materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Cascaded Kalman and particle filters for photogrammetry based gyroscope drift and robot attitude estimation

Based on a cascaded Kalman–Particle Filtering, gyroscope drift and robot attitude estimation method is proposed in this paper. Due to noisy and erroneous measurements of MEMS gyroscope, it is combined with Photogrammetry based vision navigation scenario. Quaternions kinematics and robot angular velocity dynamics with augmented drift dynamics of gyroscope are employed as system state space model. Nonlinear attitude kinematics, drift and robot angular movement dynamics each in 3 dimensions result in a nonlinear high dimensional system. To reduce the complexity, we propose a decomposition of system to cascaded subsystems and then design separate cascaded observers. This design leads to an easier tuning and more precise debugging from the perspective of programming and such a setting is well suited for a cooperative modular system with noticeably reduced computation time. Kalman Filtering (KF) is employed for the linear and Gaussian subsystem consisting of angular velocity and drift dynamics together with gyroscope measurement. The estimated angular velocity is utilized as input of the second Particle Filtering (PF) based observer in two scenarios of stochastic and deterministic inputs. Simulation results are provided to show the efficiency of the proposed method. Moreover, the experimental results based on data from a 3D MEMS IMU and a 3D camera system are used to demonstrate the efficiency of the method.     

An intelligent hybrid meta-heuristic for solving a case of no-wait two-stage flexible flow shop scheduling problem with unrelated parallel machines

This paper addresses the problem of no-wait two-stage flexible flow shop scheduling problem (NWTSFFSSP) considering unrelated parallel machines, sequence-dependent setup times, probable reworks and different ready times to actualize the problem. The performance measure used in this study is minimizing maximum completion time (makespan). Because of the complexity of addressed problem, we propose a novel intelligent hybrid algorithm [called hybrid algorithm (HA)] based on imperialist competitive algorithm (ICA) which are combined with simulated annealing (SA), variable neighborhood search (VNS) and genetic algorithm (GA) for solving the mentioned problem. The hybridization is carried out to overcome some existing drawbacks of each of these three algorithms and also for increasing the capability of ICA. To achieve reliable results, Taguchi approach is used to define robust parameters' values for our proposed algorithm. A simulation model is developed to study the performance of our proposed algorithm against ICA, SA, VNS, GA and ant colony optimization (ACO). The results of the study reveal the relative superiority of HA studied. In addition, potential areas for further researches are highlighted.     

Adoption of New Irrigation Technology Under Production Risk

This paper investigates the factors affecting adoption of new irrigation technologies and also addresses the linkage between this type of technology and production risk. The risk-premium associated with the use of water is estimated by adapting a moment-based approach. Farm-level data were collected from a sample of 187 wheat farms, located in the three major districts of Fars province of Iran during the years 2002 and 2003. Results of this study demonstrate that the risk premium decrease with new irrigation technology. Also, it is concluded that the farmer-specific relative risk premium has positive and significant effect on the decision to adopt the new irrigation technologies. So, farmers that are more risk-averse with respect to their use of water are more likely to adopt new irrigation technologies that allow them to save water and decrease their production (yield) risk.     

Production and radiochemical separation of no-carrier-added <Superscript>88</Superscript>Y by liquid-liquid extraction

A method was suggested for the cyclotron production of ⁸⁸Y with liquid-liquid extraction. The sedimented ^natSrCO₃ target was irradiated with 18-MeV protons at current of 20 μA for 10 h. The ⁸⁸Y yields of about 1.326 MBq μA⁻¹ h⁻¹ were experimentally obtained. Solvent extraction of no-carrier-added ⁸⁸Y from irradiated strontium carbonate target in the hydrochloric acid solution was studied using di(2-ethylhexyl) hydrogen phosphate (HDEHP). The optimum separation was achieved in the system n-hexane/10% HDEHP-0.1 M HCl. Yttrium radionuclides were recovered from the HDEHP phase by stripping with 60 ml of 9 M HC1. Also, excitation functions of the proton, deuteron, and α-particle induced reactions of ⁸⁹Y, ⁸⁸Sr, ^natSr, and natRb were determined using computer codes and compared to the existing data.