Evapotranspiration Modeling Using Different Tree Based Ensembled Machine Learning Algorithm

Water Resources Management - The present study investigates and evaluate the scope and potential of modern computing tools and techniques such as ensembled machine learning methods in estimating...     

Influence of the shape of fiber cross section on fabric surface characteristics

Fiber cross sections for use in textiles and composites are becoming more and more complex. Shape impacts fiber or filaments properties and therefore the yarn and fabric characteristics. This paper presents the influence of the fiber cross section on the fabric surface characteristics. The material used was polyester staple fibers, of four different shapes: round, scalloped oval, cruciform and hexachannel. All fibers had the same cut length with different fineness. Yarns obtained from these fibers had nominally the same yarn count, torsion value and structure. Plain jersey fabrics were knitted from each of the yarns under identical conditions and then relaxed prior to testing. Friction behavior was evaluated and a roughness-friction criterion developed. An indirect measurement of the real area of contact was obtained in order to provide roughness and friction properties. The influence of fiber cross section on yarn bending rigidity and on the state of the knitted fabric surface was characterized.     

On the issue of urea phase connectivity in formulations based on molded flexible polyurethane foams

Lithium chloride was added to systematically alter the phase separation behavior, and hence, the nature of urea phase connectivity, in a series of plaques based on molded flexible polyurethane foam formulations. The plaques prepared were found to possess varied levels of urea phase connectivity that was examined at different length scales using several characterization techniques. SAXS, TEM, and t‐AFM were used to show that addition of LiCl systematically reduced the formation of the urea aggregate structures typically observed in flexible polyurethane foam formulations and thus led to a loss in urea phase connectivity at the macrolevel. SAXS, DSC, and DMA revealed that formulations with and without LiCl exhibited similar interdomain spacings and soft segment glass transitions, suggesting that incorporation of LiCl did not prevent the plaques from undergoing partial microphase separation. WAXS demonstrated that addition of LiCl led to a loss in the local ordering of the hard segments within the microdomains, i.e., it led to a reduction of microlevel connectivity or the regularity in segmental packing of the urea phase. High‐magnification t‐AFM images showed that increasing the LiCl content dispersed the urea component more homogeneously and in a more uniform manner in the polyol matrix, and thus altered the connectivity of the urea phase at the microdomain level. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2956–2967, 2002     

Infrared study of salt free and salt treated cellulose pyrolysis under nitrogen atmosphere

The pyrolysis under nitrogen of salt free and salt treated cellulose was studied by infrared spectroscopy. The results confirm the unzipping mechanism suggested by DTA and TGA studies, and show this mechanism to apply to the untreated and salt treated samples. The results also show the unzipping to stop at the stage of char formation. The onset of this stage was found to occur after the volatilization of only 45–50% of the initial sample of the borax treated cellulose, compared with 65–70% of the KCl treated cellulose and 80–85% of the untreated cellulose.     

A closed-loop cross-correlation method for detecting model mismatch in MIMO model-based controllers

Correlation between a dithering signal and the prediction error has been used for detecting model mismatch in univariate model based control systems. This paper extends that approach to MIMO control systems. A closed-loop cross-correlation method is presented to detect which specific input-output pairings of a model-based controller are mismatched. This method may be used in screening the complete set of models and in selecting candidate models for re-identification. The method first finds the rows and columns of the transfer function matrix that contain mismatch, and then the candidates are found by the intersection of the said rows and columns. Placing the system under partial control, whereby one or more of the manipulated variables are held constant, can be used to further reduce the set of candidate models.     

Acetals as nucleating agents for polypropylene

Nucleating agents increase the impact strength, tensile strength, and tensile elasticity modulus of semicrystalline polymers. Nucleating agents also decrease product cycle times, resulting in a cost savings per product unit. We have synthesized and tested 15 compounds as nucleactors for polypropylene. Of these, trinapthylidene sorbitol, tri-(4-methyl-1-naphthylidene)sorbitol, tri-(4-methoxy-1-naphthylidene) sorbitol, and dibenzylidene xylitol are efficient nucleators of polypropylene. Trinaphthylidene sorbitol (tns) has two major diastereomers: The “S” diastereomer yields a faster crystallization rate for polypropylene than does the commercial nucleator dibenzylidene sorbitol (Millad 3905). Crystallization rates are 208 and 88, respectively (t min^?1 × 1000). The “R” diastereomer, however, is a poor nucleator and interferes with the nucleating activity of the “S” diastereomer. A 52/48 mixture of diastereomers does not nucleate polypropylene, even at twice the concentration. This is first time that the importance of stereochemistry has been demonstrated in the nucleating action. © 1994 John Wiley & Sons, Inc.     

On routing in large WDM networks

An important problem in WDM network design is to construct a logical topology and determine an optimal routing over that topology. Mixed Integer Linear Program (MILP) formulations to generate optimal solutions for this problem have been presented. Such formulations are computationally intractable, even for moderate sized networks. A standard approach is to decouple the problem of logical topology design and the problem of routing the traffic on this logical topology. Heuristics for finding the logical topology exist and a straight-forward linear program (LP), based on the node-arc formulation can be used to solve the routing problem over a given logical topology. We have found that such LP formulations become computationally infeasible for large networks. In this paper, we present a new formulation, based on the arc-chain representation, for optimally routing the specified traffic over a given logical topology to minimize the congestion of the network. We have used the revised simplex method incorporating an implicit column generation technique, and exploited the special Generalized Upper Bounding structure as well as the possibility of eta-factorization for efficiently updating the dual variables and finding the solution. Experimental results on a number of networks demonstrate the suitability of this approach.     

Generalized four-point characterization method using capacitive and ohmic contacts

In this paper, a four-point characterization method is developed for samples that have either capacitive or ohmic contacts. When capacitive contacts are used, capacitive current- and voltage-dividers result in a capacitive scaling factor not present in four-point measurements with only ohmic contacts. From a circuit equivalent of the complete measurement system, one can determine both the measurement frequency band and capacitive scaling factor for various four-point characterization configurations. This technique is first demonstrated with a discrete element four-point test device and then with a capacitively and ohmically contacted Hall bar sample over a wide frequency range (1 Hz-100 kHz) using lock-in measurement techniques. In all the cases, data fit well to a circuit simulation of the entire measurement system, and best results are achieved with large area capacitive contacts and a high input-impedance preamplifier stage. An undesirable asymmetry offset in the measurement signal is described which can arise due to asymmetric voltage contacts.     

Social Profile Aware AODV Protocol for Ad-Hoc Social Networks

Wireless Personal Communications - Ad-hoc social networks are required to strengthen local communication between people. Mobile ad-hoc social networks have emerged as self-configuring and...