bluuebunny/crossref_metadata_2025 huggingface dataset:
Bone Meal Waste and Ca(HPO4)2 as Reinforcing Filler for NR and CR and their Blends Compared with Conventional White Filler
Authors: Helaly F. M. , El-Sabbagh S. H.
Published: July 2008

The reinforcement of rubber by fillers is of great practical and technical importance. Bone meal waste and Ca(HPO4)2, were evaluated as reinforcing fillers for natural, chloroprene rubber and their blend comparing them with white conventional filler, CaCO3. It was clearly seen that, the properties of the recommended rubber were dependent on the type as well as the concentrations of the investigated fillers. The rheological properties of rubber mixes containing bone meal and Ca(HPO4)2 were improved and the behaviour of the mixes looks like those containing CaCO3. Also, the physico-mechanical properties as tensile strength and modulus at 100% strain increased by increasing the investigated filler contents in the vulcanisates. The scanning electron microscope illustrates a high degree of surface homogeneity and good dispersion of the particulate fillers encased within the rubber matrix.
Improving the Flexural Modulus and Thermal Stability of Pitch by the Addition of Silica Fume
Authors: Mei Zhen , Chung D. D. L.
Published: July 2008

The effects of sand and silica fume on the flexural modulus and thermal stability of pitch were investigated mechanically and thermomechanically. Both modulus and softening temperature were increased by sand addition and further increased by the further addition of silica fume, except that an excessive amount of silica fume caused the modulus to decrease. An effective composition involved 29 vol.% sand and 2 vol.% silica fume.
Using a Finite Volume Approach to Simulate the Mould Filling in Compression Moulding
Authors: Vahlund C. F.
Published: July 2008

A mould filling simulation of an automotive hood geometry was performed using a general purpose finite volume computational fluid dynamics (CFD)code. The simulation was performed as a homogenous multi-phase model using mass sinks to remove excess air from the computational domain and performed in three-dimensions. The kinematic boundary condition was modelled using a hydrodynamic friction at the mould boundaries corresponding to that in the Barone and Caulk approximation. The fibre orientation distribution was simulated through-out the closure phase using the Folgar Tucker equation for the reorientation of the fibres and orientation tensors to describe the local orientation for each element.

The paper presents the methodology for, and the possibilities of, using a general purpose CFD code for these kinds of simulations. Both mould filling simulations in general can be performed and special cases where the standard simplifications of the governing equations are not valid can be investigated.
Synthesis and Biological Evaluation of Peg-Substituted Macromolecular Prodrugs of Mitomycin C
Authors: Hoste K. , Schacht E. , Rihova B.
Published: July 2008

Poly(ethylene glycol) (PEG)-substituted macromolecular mitomycin C (MMC)-derivatives were synthetized using poly[N5-(2-hydroxyethyl)-L-glutamine] as the polymeric backbone. As an oligopeptide spacer between the drug and the polymer, tetrapeptide gly-phe-ala-leu was selected. To study the influence of PEG side groups on the antitumor activity of the derivatives, the conjugates were evaluated biologically in vitro and in vivo. The in vitro experiments showed only a minor influence of the PEGside groups on the antitumor activity. The results of the in vivo experiments on mice with a human type tumor were promising. Some derivatives lead to a remarkable tumor size regression. Furthermore, in vivo treatment of tumor bearing mice with the macromolecular MMC derivatives resulted in significantly longer survival times compared to free MMC.
Invertase Stabilization by Chemical Modification of Sugar Chains with Carboxymethylcellulose
Authors: Ramírez Hector L. , Chico Belkis , Villalonga Reynaldo , Hoste Katty , Schacht Etienne H.
Published: July 2008

Invertase from Saccharomyces cerevisiae was activated by periodate treatment and further reacted with ethylenediamine/sodium borohydride. Carboxymethylcellulose was then attached to ethylenediamine-modified invertase using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as coupling agent. The modified enzyme contained 3.5 mol of polysaccharide per mol of holoenzyme, and retained about 56% of the initial invertase activity. The thermostability of invertase increased from 64 to 70° C, the thermal inactivation at different temperatures ranging from 60 to 70° C was markedly reduced for polymer-modified enzyme. An increase of 9.1 kJ mol−1 in activation free energy of inactivation was determined for invertase after modification. Functional stability was increased for carboxymethylcellulose-invertase complex in the range of pH between 2.0 and 12.0. The conjugate was also more resistant to denaturation by 6 M urea solution.
Performance Modification of Chitosan Membranes Induced by Gamma Irradiation
Authors: Yang Fei , Li Xunhu , Cheng Mingyu , Gong Yandao , Zhao Nanming , Zhang Xiufang , Yang Yinye
Published: July 2008

Trauma of the nervous system often results in permanent functional loss because the spontaneous regeneration of nerves is very difficult. Thus, various methods have been developed to facilitate the restoration of damaged nerve. The biodegradable nerve conduit is one of the most promising methods for nerve regeneration. Chitosan, a natural polysaccharide that has excellent biocompatibility and biodegradability, can be used as conduit material. But, nerves regenerated by nerve conduits made from chitosan have some problems, for example, with their mechanical properties. This article shows that the mechanical propertiesof chitosan film were markedly improved by selected doses of gamma radiation and cell culturing experiments on the surface of the irradiated chitosan film indicated that the film still has excellent biocompatibility.
Regression of Solid Tumour Using Laser and 5-Aminolevulinic Acid in Mice
Authors: Mohanan P. V. , Jayasree R. S. , Gupta A. K.
Published: July 2008

Solid tumour reducing effect in Swiss albino mice induced with Dalton’s Lymphoma Ascites tumour cells (DLA) and Ehrlich Ascites tumour cells (EA) was determined with the application of He–Ne and Nd: YAG lasers along with the photosensitising agent 5-Aminolevulinicacid (ALA). The experiment was designed with six groups and each group consisted of six animals. Animals in Groups I–III were injected with DLA cell lines and Groups IV–VI were injected with EAcell lines (1 × 106 in 0.1 ml saline) subcutaneously in the right hind limb of mice to induce solid tumours. The tumour was further treated with photosensitiser induced laser therapy. The hyperthermic effect of Nd: YAG laser on tumour reduction was also evaluated. The results of the study suggest that the combination of He–Ne laser and 1 W Nd: YAG laser along with the photosensitiser 5-Aminolevulinic acid is a very effective therapeutic method for the treatment of tumour of DLA and EA cell lines. It is clear from the results that this mode of therapy very well depends on the type of tumour that has to be treated.
Changes in Cisplatin Delivery Due to Surface-Coated Poly (Lactic Acid)–Poly(∊-Caprolactone)Microspheres
Authors: Chandy Thomas , Wilson Robert F. , Rao Gundu H. R. , Das Gladwin S.
Published: July 2008

Smooth muscle cell proliferation plays a major role in the genesisof restenosis after angioplasty or vascular injury. Local delivery of agents capable of modulating vascular responses, have the potential to prevent restenosis. However, the development of injectable microspheres for sustained drug delivery to the arterial wall is a major challenge. We demonstrated the possibility of entrapping an antiproliferative agent, cisplatin, in a series of surface coated biodegradable microspheres composed of poly(lactic acid)– poly(caprolactone) blends, with a mean diameter of 2–10 mm. The microspheres were surface coated with poly ethylene glycol (PEG), chitosan (Chit), or alginate (Alg). A solution of cisplatin and a 50: 50 blend of polylactic acid (PLA)– polycaprolactone (PCL) dissolved in acetone–dichloromethane mixture was poured into an aqueous solution of PEG (or polyvinyl alcohol or Chit or Alg) with stirring using a high speedhomogenizer, for the formation of microspheres. Cisplatin recovery inmicrospheres ranged from 25–45% depending on the emulsification system used for the preparations. Scanning electron microscopy revealed that the PLA–PCL microspheres were spherical in shape and had a smooth surface texture. The amount of drug release was much higher initially (20–30%), this was followed by a constant slow-release profile for a 30-day period of study. It has been found that drugrelease depends on the amount of entrapped drug, on the presence of extra cisplatin in the dispensing phase, and on the polymer coatings.This PEG or Alg-coated PLA/PCL microsphere formulation may have potential for the targeted delivery of antiproliferative agents to treat restenosis.
The Telescoping Suture –Part 1: Does this Technique Improve the Mechanical Behavior of a Biomaterial?: Calf Pericardium
Authors: Páez J. M. García , Herrero E. Jorge , Rocha A. , Martín-Maestro M. , Castillo-Olivares J. L. , Millán I. , Sanmartín A. Carrera , Cordón A.
Published: July 2008

The authors study the mechanical behavior of calf pericardium employed in the construction of cardiac valve leaflets when subjected to telescoping suture, followed by tensile stress until rupture.

One hundred twenty pericardial tissue samples were employed, 60 cut from root-to-apex and another 60 cut in transverse direction. Each of these two groups consisted of 12 control samples that were left unsutured and four sets of 12 samples each that were rejoined by telescoping suture using silk, Prolene, nylon or Gore-Tex., and subjected to tensile stress. At the rupture of the sutured tissues, the tensile stress of the suture materials ranged between 57.54 MPa for the series sewn lengthwise with Gore-tex and 114.08 MPa for the series sewn crosswise with silk. At these levels of stress, the deformation of the suture thread was much less marked than that of the calf pericardium, and internal stresses were produced that were difficult for the biomaterialto absorb.

There was a loss of real load in all the sutured series when the observed resistance to rupture, expressed in kilograms, was compared with the estimated value. This loss of resistance did not invalidate the telescoping suture technique since the resistance to rupture was still much greater than that associated with suturing the two edges of the cut pericardium together. This report confirms the deleterious role of the shear force generated in the pericardium by the suture.
Anticoagulant Activity of Immobilized Heparin on the Polypropylene Nonwoven Fabric Surface Depending upon the pH of Processing Environment
Authors: Tyan Yu-Chang , Liao Jiunn-Der , Wu Yi-Te , Klauser Ruth
Published: July 2008

Antenna couplingmicrowave plasma enables a highly oxidative treatment of the outmost surface of polypropylene (PP) nonwoven fabric within a short time period. Subsequently, grafting copolymerization with acrylic acid (AAc) makes the plasma-treated fabric durably hydrophilic and excellent in water absorbency. With high grafting density and strong water affinity, the pAAc-grafted support greatly becomes feasible as an intensive absorbent and as a support to promote heparin immobilization through amide bonds. For heparin immobilized in acidic condition, the carbonate groups of the molecule tend to dissolve and passive encapsulation of the molecule prevents its functional groups from bondingwith the carboxylic acid of pAAc. This effect leads to inhibit the immobilization process and consequently reduces the quantity as well as the bioactivity of the immobilized heparin. In alkaline processing environment, the oxidized uronic acid residues in heparin-related glycans are presumably cleaved and the removal of some oxidized residuals before immobilization process is likely to reduce the chain length of heparin. In the latter case, anticoagulant Factors X and XII, but not thrombin, are unaffected. Anti-coagulant activity test using activated partial thromboplastin time (aPTT) is more sensitive in assessingheparin-immobilized surfaces, since it corresponds to Factor X and initiates the inhibition of Factor XII and thrombin. Likewise, platelets adhesion on the surfaces decreases as the process shifted from acidic to alkaline condition, whereas the hydrophilic character of the grafted pAAc markedly contributes to extend physical insertion of platelets. The immobilized heparin has a great part of original bioactivity, depending on the pH of the processing environment and the immobilized quantity. Relative bioactivity based upon aPTT tests is partially held longer than 90 days for the sample prepared in the alkaline or neutral environment.
Comparative Evaluation of Shape Memory Alloy Constitutive Models with Experimental Data
Authors: Prahlad Harsha , Chopra Inderjit
Published: July 2008

This paper presents research aimed at reviewing and comparing constitutive models for Shape Memory Alloy (SMA) behavior under uniaxial loading with experimental data over the entire thermomechanical range of test conditions. Three commonly used representative constitutive models predicting quasistatic SMA behavior – Tanaka, Liang and Rogers, and Brinson are examined, and are compared with experiments under quasistatic loading conditions. Important distinctions regarding the definition of material constants in these models are pointed out, and the method of obtaining material parameters from experiments is presented. Observations regarding substantial differences between resistive and environmental heating methods of the wire are also presented. It is shown that most of the models are in good overall agreement with isothermal and constrained recovery test data. Several observations regarding the comparison of model predictions with experimental test data and the implementation of the models in a formal code are discussed. Experimental characteristics observed under nonquasistatic loading are used to point out some deficiencies in these models, and the necessity for modeling refinements incorporating these effects is discussed.
Lyapunov-Based Control of a Bridge Using Magneto-Rheological Fluid Dampers
Authors: Wang Xiaojie , Gordaninejad Faramarz
Published: July 2008

This study focuses on the effect of semi-active magneto-rheological fluid (MRF) dampers in reducing the response of a scaled bridge structure subjected to a random loading. A fluid-mechanics based model that can characterize the nonlinear dynamic behavior of MRF dampers is employed. A state-variable model for an integrated system of a scaled, two-span bridge and two MRF dampers is established. A feedback on-off control law is employed based on Lyapunov approach that guarantees the system stability for uncertain bounded input disturbances. An output feedback Lyapunov controller is implemented in the experimental study to verify the presented method. Both the theoretical and experimental studies show that the Lyapunov based control systems can effectively reduce the relative displacement between the deck and the abutment of the bridge when subjected to various input motions. In addition, when comparing to the experiment results, it is demonstrated that the proposed analytical model can predict the response of the system, accurately.
Multiple Application of Magnetorheological Effect in High Precision Finishing
Authors: Kordonski William , Golini Don
Published: July 2008

Magnetorheological finishing (MRF) is enabling technology that may produce surface accuracy of the order of 10 nm peak-to-valley and surface micro-roughness less than 10A. In this technique, magnetorheological fluid performs the primary function, which is deterministic material removal. There are several auxiliary devices that also function on a “smartness” of magnetorheological fluid. A non-intrusive magnetorheological valve is an integral part of the finishing machine “circulatory system” and provides the pump “stiffness” and computer control of the flow rate. To provide MR polishing fluid continuous circulation, a special means for fluid removal from the polishing wheel and returning to the delivery system has been designed. Once the fluid leaves the polishing zone, it is removed from the wheel surface by a suction cup. The cup has a magnetic system that forms a dynamic magnetorheological fluid seal in the gap between the cup and the wheel surface. Finite element analysis software has been used for magnetic systems and flow design and optimization.
What Makes a Good MR Fluid?
Authors: Carlson J. David
Published: July 2008

Experience in manufacturing magnetorheological (MR) fluids for commercial application has shown that some of the greatest barriers to commercial success are not factors or conditions normally considered in the laboratory. The present paper looks at conditions found in MR fluid devices operating in real-world applications where shear rates may exceed 105 s 1 and devices are called upon to operate for very long periods of time. The problem of “In-Use-Thickening” wherein a MR fluid subjected to long-term use progressively thickens until it eventually becomes an unworkable paste is presented. The search for a solution to this heretofore unrecognized problem delayed commercial introduction of the Lord truck seat damper system for several years. Today, good fluids are able to operate for long periods with minimum in-use-thickening.
Investigation of Dynamic Properties and Control Method Influences on MR Fluid Dampers’ Performance
Authors: Milecki Andrzej
Published: July 2008

Semi-active, controllable fluid dampers and their control devices are described and studied in this paper. Such dampers can be used to eliminate oscillations in different servo drive robots and machine tools systems, where their good dynamic parameters are required. In this paper, different control circuits and its influence on MR damper properties are investigated. The experimental results of coil current transients response during switching on and off with different circuits and elements are shown. Construction of the above mentioned damper is described and finally, experimental results of control circuits influence on dampers’ dynamic performance are presented.
Impact of Droplets of Magneto-Rheological Suspension Under Applied Magnetic Fields
Authors: Sudo S. , Funaoka M. , Nishiyama H.
Published: July 2008

An experimental study is presented of the dynamic behavior of the impacting droplet of magneto-rheological suspension under applied magnetic fields. Effects of magnetic fields on the impact phenomena between a MR fluid droplet and paper on the hard rubber mat were revealed with a three-dimensional motion analysis system. In case of perpendicular magnetic field to a target surface, the MR fluid droplet did not collapse completely by its impact, but MR fluid spikes were formed by the magnetic field. In case of parallel magnetic field to a target surface, the MR fluid droplet showed complicated deformation. In case of strong parallel field, the MR fluid droplet showed breakup into few droplets.
Damping of an Elastic Beam Using an MR Suspension in the Squeeze Mode
Authors: Bashtovoi V. G. , Kabachnikov D. N. , Bossis G.
Published: July 2008

Magneto-rheological (MR) suspensions are actively used in damping devices. As a rule these suspensions are made of magnetic particles in a carrier fluid. In this paper we study a device aiming to control the vibration of a plate by using a MR fluid. The magnetic field is used both to control the viscosity and to confine the drop of fluid in the field gradient. A theoretical investigation of the motion of the plate is given together with the prediction of the damping decrement, assuming that the magnetic fluid follows a Bingham law. Experiments have been realized and are compared with theoretical predictions.
Electro-Structured Fluid Seals
Authors: Atkin R. J. , Ellam D. J. , Bullough W. A.
Published: July 2008

The aim of this paper is to bring together various works on concentrically located rotating shaft seals which utilise electro-structured fluid sealant, in order to produce a generalised approach to their design, thus resolving seemingly incompatible reports on the effects of rotational speed on sealing capabilities. In turn, the results from these works are reviewed, a viscoplastic analysis of the 2-D problem is presented and the effects on leakage rate of radius ratio, rotational speed and axial pressure gradient as they interact with fluid properties are illustrated.
Evaluation of Magnetorheological Suspensions Based on Carbonyl Iron Powders
Authors: Bombard Antonio J. F. , Knobel Marcelo , Alcantara Maria Regina , Joekes Ines
Published: July 2008

The particle size distribution and magnetic susceptibility of some commercial carbonyl iron powders (code names CC, CS, HQ, OX and SM) were measured. The particle size of the powders increases as follows: HQ<SM<CC OX<CS. The magnetic susceptibility increases in the order: HQ OX SM CC CS. Magnetorheological suspensions (MRS) with 66% w/w of iron were prepared and their rheological properties were evaluated at no field, 100, 200 and 300 Oe. The yield stress under 300 Oe measured with strain-stress curves increases in the order: HQ OX<SM<CC<CS, showing direct correlation with the susceptibility. The plastic viscosity without field increases in the order: CS<CC<OX<SM<HQ, an inverse correlation with particle size. These results show that the particle size and/or size distribution can be another important property of the powders, together with magnetic susceptibility on the formulation of improved MRS.
A Simple One Dimensional Robot Joint Based on the ER Linear Reversing Mechanism
Authors: Tan K. P. , Bullough W. A. , Stanway R. , Sims N. , Johnson A. R. , Tozer R. C.
Published: July 2008

The feasibility of using a well-known twin ER clutch linear reversing mechanism as a robotic actuator is demonstrated. High speed of response, displacement and positional accuracy can be obtained bi-directionally. A validated mathematical model of the apparatus provides a basis for the control strategy. Positional accuracy is enhanced by an ER brake which works in sequence with the clutch excitation switches. The robot arm, in rotational displacement is tested over a large number of cycles, speeds, displacements and inertial loads and the quality of control compared to that of competitive conventional servo motors.
Statistical Damage Classification Under Changing Environmental and Operational Conditions
Authors: Sohn Hoon , Worden Keith , Farrar Charles R.
Published: July 2008

Stated in its most basic form, the objective of damage diagnosis is to ascertain simply if damage is present or not based on measured dynamic characteristics of a system to be monitored. In reality, structures are subject to changing environmental and operational conditions that affect measured signals, and environmental and operational variations of the system can often mask subtle changes in the system’s vibration signal caused by damage. In this paper, a unique combination of time series analysis, neural networks, and statistical inference techniques is developed for damage classification explicitly taking into account these ambient variations of the system. First, a time prediction model called an autoregressive and autoregressive with exogenous inputs (AR-ARX) model is developed to extract damage-sensitive features. Then, an autoassociative neural network is employed for data normalization, which separates the effect of damage on the extracted features from those caused by the environmental and vibration variations of the system. Finally, a hypothesis testing technique called a sequential probability ratio test is performed on the normalized features to automatically infer the damage state of the system. The usefulness of the proposed approach is demonstrated using a numerical example of a computer hard disk and an experimental study of an eight degree-of-freedom spring-mass system.
Quasi-Steady Bingham Biplastic Analysis of Electrorheological and Magnetorheological Dampers
Authors: Dimock Glen A. , Yoo Jin-Hyeong , Wereley Norman M.
Published: July 2008

Electrorheological (ER)and magnetorheological (MR)fluids are characterized by an increase in dynamic yield stress upon application of a magnetic field. The Bingham plastic model has proven useful in modeling flow mode dampers utilizing ER and MR fluids. However, certain MR fluids can exhibit shear thinning behavior, wherein the fluid’s apparent plastic viscosity decreases at high shear rates. The Bingham plastic model does not account for such behavior, resulting in overprediction of equivalent viscous damping. We present a Bingham biplastic model that can account for both shear thinning and shear thickening behaviors. This approach assumes a bilinear post yield viscosity, with a critical shear rate specifying the region of high shear rate flow. Furthermore, the model introduces non-dimensional terms to account for the additional parameters associated with shear thinning and thickening. A comparison is made between Bingham plastic and Bingham biplastic force responses to constant velocity input, and equivalent viscous damping is examined with respect to nondimensional parameters.
Performance Analysis of ER/MR Impact Damper Systems Using Herschel-Bulkley Model
Authors: Lee Dug-Young , Choi Young-Tai , Wereley Norman M.
Published: July 2008

Performance analysis for electrorheological (ER) and magnetorheological (MR) fluid-based impact damper systems is evaluated on the basis of the Herschel-Bulkley shear model. Generally, ER-MR dampers have been analyzed based on the simple Bingham-plastic shear model. However, the Bingham-plastic shear model cannot well describe the behavior of the damper under conditions of high velocity and high field input. Therefore, in this study, the Herschel-Bulkley shear model, in which the constant post yield plastic viscosity in the Bingham model is replaced with a power law model dependent on shear rate, is used to assess the performance of ER-MR impact damper systems. In doing so, an ER-MR impact damper system is proposed and its governing equation of motion is derived on the basis of the Herschel-Bulkley shear model. Then, computer simulation is done to analytically evaluate characteristics of the ER-MR impact damper system under impact loads for constant current input and embedding end-stop on-off control algorithm. As an important parameter in the Herschel-Bulkley shear model, effects of the flow behavior index, n, that is the degree of shear thinning or shear thickening, on the performance of the impact damper system are shown.
Wave Propagation in Sandwich Plates with Periodic Auxetic Core
Authors: Ruzzene Massimo , Mazzarella Luca , Tsopelas Panagiotis , Scarpa Fabrizio
Published: July 2008

The wave propagation in and the vibration of sandwich plates with cellular core are analyzed and controlled. Negative Poisson’s ratio (auxetic) core materials of different geometry placed periodically in the plate introduce the proper impedance mismatch necessary to obstruct the propagation of waves over specified frequency bands (stop bands) and in particular directions. The location and the extension of the stop bands and the directions of wave propagation can be modified by proper selection of the periodicity and of the geometrical and physical properties of the core.

A finite element model is developed to predict the dynamic response of three-layered sandwich panels with honeycomb core. The finite element model along with the theory of periodic structures evaluates the influence of core materials of different geometry placed periodically along the two dimensions of the structure. This combined analysis yields the phase constant surfaces for the considered sandwich plates, which define location and extension of the stop bands, as well as the directions of wave propagation at assigned frequency values. The analysis of the phase constant surfaces and the evaluation of the harmonic response at specified frequencies demonstrate the plates’ directional properties, whose spatial patterns strongly depend on the configuration of the periodic core and on the excitation frequency. Auxetic honeycombs are here considered as core materials in order to obtain maximum design flexibility. Their elastic and inertial characteristics in fact vary substantially with their internal geometry. For given configurations they outcast up to five times the corresponding properties of traditional hexagonal honeycombs.

The presented numerical results demonstrate the unique characteristics of this class of two-dimensional periodic structures, which behave as directional mechanical filters. The findings of the study suggest that optimal configurations for the periodic cellular core may be identified in order to design passive composite panels, which are stable and quiet over desired frequency bands and which fit desired transmissibility levels in particular directions. Such unique filtering capabilities are achieved without requiring additional passive or active control devices and therefore without compromising the size and the weight of the layered structure.
Characterization of Isotropic Damage Using Double Scalar Variables
Authors: Tang C. Y. , Shen W. , Peng L. H. , Lee T. C.
Published: July 2008

In this study, double scalar damage variables have been used to characterize the state of isotropic damage. The damage influence tensorrelating to the double scalar damage variables of damaged material isthus formulated based on the hypothesis of stress equivalence for this model. The specific damage energy release rate is adopted to represent the thermodynamics force conjugating to the double damage variables. Based on the irreversibility laws of thermodynamics, these forceshave been formulated directly from the degradation of effective engineering elastic coefficients in stress space. The contribution of bothdilatation and distortion of material to the specific damage energy density release rate in loading process has been explained. The doublescalar damage variables of isotropic solid material with penny-shape cracks and spherical voids randomly distributed have been determined on the basis of the micro-mechanics theory, respectively. In addition, the damage influence tensor and the specific damage energy release rate were obtained by using the experimental results of pre-strained aluminum alloy 2024T3 specimens under uni-axial tension tests.
Micromechanics of Stiffness Damage in Ceramic-Based Fiber-Reinforced Composites
Authors: Araki S. , Saito K.
Published: July 2008

The micromechanical analysis is performed to elucidate the stiffness reduction damage in the ceramic/ceramic composite whose matrix rupture strain is smaller than that of fibers. It is assumed that damage mechanism in the composite consists mainly of crack bridging fiber and interfacial sliding between the matrix and fibers. Energy release rate for a matrix crack and energy dissipation by the interfacial sliding was formulated by means of the inclusion modeling in micromechanics. Macroscopic stiffness at the given applied stress was derived in terms of the current lengths of matrix cracks. Finally, applicability of a parameter of damage accumulation in the material and its effect on macroscopic stiffness were discussed by the use of macroscopic stress-strain curves.
Constitutive Modeling of Creep and Damage Behaviors of the Non-Mises Type for a Class of Polycrystalline Metals
Authors: Kawai M.
Published: July 2008

Phenomenological constitutive models to describe the creep and damage behaviors that deviate from the von Mises type for a class of polycrystalline materials are developed. Theoretical and empirical approaches are taken to the formulation. The effective stresses that govern the rates of creep and damage are scaled to describe any deviation from the response of the von Mises type. A general form of scaling parameter is proposed which can consider the hydrostatic stress and/or the third invariant of the stress deviator. A kinematic hardening model is first formulated on the basis of irreversible thermodynamics using the scaling parameters for creep and damage. Then, two kinds of empirical basis models are presented for cases of kinematic hardening and isotropic hardening, respectively. The proposed models can describe the primary, secondary and tertiary creep behaviors and distinguish between the creep and damage behaviors under different modes of loading. To illustrate the features of the proposed models, numerical simulations of the unequal creep behaviors under tension, compression, and torsion are carried out and compared with experimental results.
Weight Optimization of Sandwich Panel with Acoustic Constraints, Experimental Verification
Authors: Wennhage Per
Published: July 2008

Weight optimization of a sandwich panel was performed. The constraints were both mechanical, in the form of stiffness and strength constraints, and acoustic, in the form of a required sound reduction index, R. The sound reduction index of the optimized panel and an initial configuration was measured under laboratory conditions and the results were compared to predicted values. Predictions and measurements of the sound reduction index were made in third-octave frequency bands. It was shown that the difference in R between the initial panel and the optimized one was predictable using the acoustic models and that the optimized panel fulfilled the constraints. The weighted average reduction index, RW, was also used to provide an engineering number for comparison.
The Role of Construction Textiles in Indoor Environmental Pollution
Authors: White W. Curtis , Kuehl Mark H.
Published: July 2008

Microbial contamination (mold, mildew, bacteria, fungus) is a leading cause of indoor environmental contamination and has generated serious concerns in the construction and building industries.Recent court cases in Texas and other states have required builders to redefine their role in dealing with the issue of microbial contamination during construction.

Microbes are diverse, found everywhere, and highly adaptive.They cause short- and long-term problems within buildings through staining and deteriorating (corrosion, rotting, etc.) the structure as well as generating foul odors in the living environment.They can also cause human problems such as building related illnesses (BRI), sick building syndrome (SBS), hypersensitivity pneumonitis, allergic disorders, and infectious disorders (including Legionnaire’s Disease).

Construction textiles, which are important components of the building envelope, are key factors to indoor environmental quality.Virtually any housewrap, insulation, sealant, and exterior or interior treatment, can create significant microbiological problems for the indoor environment.This presentation identifies common construction materials and installation practices that contribute to microbial contamination in buildings.It also demonstrates how these materials and practices can be altered to control microbial contamination during construction and once the building is occupied.
pH-Responsive Model Drug Release from Silica-Poly(methacrylic acid) Interpenetrating Gel Hybrids
Authors: Suzuki Kazuya , Yumura Takeshi , Tanaka Yuko , Akashi Mitsuru
Published: July 2008

Stimuli-responsive gel was hybridized with porous silica particles, by radical polymerization of methacrylic acid (MA) in the presence of a crosslinker. Brilliant Blue FCF (BBFCF) was encapsulated in the core of the particle and its release behavior from the particle under specific stimuli was studied. PMA gel hybridized silica particles showed specific release behavior at different pH values while normal silica particles released BBFCF at the same rate at all pHs.
Use of New Aminosugar Derivatives as Comonomers for the Synthesis of Glycosylated Poly(Amido-Amines)
Authors: Casali Monica , Riva Sergio , Ferruti Paolo
Published: July 2008

New sugar functionalized poly(amido-amines) (PAA) polymers were synthesized. The PAA made by the addition polymerization of 2-methylpiperazine-2,2-bisacrylamidoacetic acid (ISA) was chosen for its potential applications in the biomedical field and the sugar monomers were obtained by chemical and enzymatic synthetic strategies. Specifically, the 2-aminoethyl fi-D-galactopyranosyl monomer was directly obtained by enzymatic catalysis, while the 2-aminoethyl amide and the 3-aminopropyl amide of lactobionic acid were obtained by ning-opening reactions of the corresponding lactone. The presence of sugar moieties in the polymer chains was confirmed by FT-IR, 'H NMR, 13C NMR analysis and calorimetric assay. The sugar content of polymer derivatives is sufficient for targeting purpose, making these compounds potential soluble drug carriers.
A New Embolization Agent: Embolization of the Kidneys with Ethylene Glycol Dimethacrylate-Hydroxyethyl Methacrylate Copolymer Microbeads
Authors: çeken Cumhur , Ayhan Hakan , PişKin Erhan , Bilgin Sadik
Published: July 2008

Ethylene glycol dimethacrylate (EGDMA)-hydroxyethyl methacrylate (HEMA) copolymer microbeads (125-150,jm in diameter) were produced by suspension polymerization. The percent of HEMA incorporated and the swelling ratio of the non-porous microbeads produced were 12% and 22.7%, respectively. Microbeads, sterilized with ethylene oxide, were used in the embolization of the kidneys of three adult mongrel dogs by angiography. The effectiveness of the embolization was examined by angiographs after each step. In the first step of the embolization, the microbeads reached the pre-capillaries and blood flow was successfully blocked, which was confirmed by accumulation of the contrast agent within the kidneys. In angiograms after another injection, as the second step, again there were neither contrast agent movement toward the kidneys nor distribution through the paranchyme. The embolized kidneys were subjected to histopathologic examinations where pathological changes were observed.
Modeling and Study of the Quasi-Static Behavior of Piezoceramic Telescopic Actuation Architectures
Authors: Brei Diann , Berner Neal T. , Alexander Paul W.
Published: July 2008

Piezoelectric stacks are often used in smart structures applications that demand large forces. However, there are numerous applications that require slightly more displacement than is available from stacks, and the performance requirements allow room for some force to be sacrificed to obtain this displacement. A new type of piezoelectric actuation architecture, referred to as telescopic, was designed to meet the need for moderate displacement amplification (up to 20 times) while still producing large forces. This architecture internally leverages the piezoelectric strain by a series of cascading shells uniquely connected by end caps such that the shells “telescope” out when activated. This paper presents an analytical model to predict the force-deflection behavior of this actuator with compliant end caps. To aid in evaluating this new architecture, the losses due to architectural features such as end caps, gap size, number of shells, and constant thickness/area are presented along with a comparison to the current state of the art.
Material Structure Design of Stress-Dependent Adaptive Stiffness
Authors: Tanaka Masao , Todoh Masahiro , Oki Kazushige , Naomi Akihisa
Published: July 2008

Use of functional material is a primitive and most promising approach to the functional structural system, e.g. adaptive/smart structures. It, however, is not always necessary for a certain aspect of such structural function. This study proposes a material structure design approach to the stress-dependent anisotropic adaptive stiffness by using the conventional linear elastic material of isotropy. The structural design problem has been formulated for the material structure consisting of mesoscopic unit cells and solved by using the simple isotropic material with penalization (SIMP) method for the topology design and the traction method for the geometry design for microstructure of the unit cell. The effectiveness of the proposed idea has been examined through numerical studies in two-dimensional cases.
High Performance Mineral Reinforcement Concentrate for LLDPE and HMW-HDPE Blown Film Extrusion
Authors: Ruiz F. A.
Published: July 2008

LLDPE-based pelletized calcium carbonate (CaCO3) concentrates utilizing two different viscosity base resins were used to add up to 20 wt% fine-ground, surface-treated CaCO3 as mineral reinforcement to LLDPE and HMW-HDPE films. Film was extruded and converted into institutional can liners on production equipment.

Concentrates based on higher viscosity resins yielded superior impact and tensile performance compared to those based on lower viscosity resins. No problems with dispersion were noted. Slightly higher melt pressure and motor current were observed, but they were still well within typical extrusion process conditions for the type of base resins used.
Progressive Failure Analysis of Plain Weaves Using Damage Mechanics Based Constitutive Laws
Authors: Kollegal M. , Chatterjee S. N. , Flanagan G.
Published: July 2008

The behavior of plain woven fabric composites is studied using three-dimensional finite elements which allows detailed modeling of the geometric complexities and spatial material variations within the fabric. Damage in the composite constituents, viz., yarn and pure matrix is modeled on a continuum basis, and related to their material constitutive behavior. The 3D constitutive laws describing pure matrix and yarn behavior are developed using a damage mechanics based approach with the dissipated energy density as the damage parameter. The strain energy dissipation (SED) concept is employed to describe the damage state and current stiffnesses of the weave constituents. A progressive failure analysis of plain woven fabrics subjected to tension and in-plane shear is carried out considering both geometric and material nonlinearities. The initiation and progression of damage within the fabric is investigated and the significant damage mechanisms outlined.
Progress in Supercritical Co2Dyeing
Authors: Hendrix Walter A.
Published: July 2008

Supercritical fluids have special properties that could lead to substantial improvements when utilized as replacements for water in wet processing of textiles. These fluids have densities and solvating powers similar to liquid solvents combined with viscosity values and diffusion coefficients like those observed for gases. In particular, these properties make supercritical carbon dioxide (SC-CO2) one of the most beneficial and environmentally acceptable solvents used in manufacturing processes today. Therefore, it is anticipated that commercial textile processes using SC-CO2 will have many advantages when compared to conventional aqueous processes.

Succesful commercialization of SC-CO2 processing will improve the economics of dyeing and other textile chemical processes by eliminating wastewater discharges, reducing energy consumption, eliminating drying, and reducing air emissions. As a result, the use of SC-CO2 is expected to make textile processing more economical and environmentally friendly.

Research groups throughout the world are investigating SC-CO2 textile processing. Succesful pilot dyeing machines have been operated and even publicly exhibited within the past few years. Research focused to developing a commercial dyeing process for polyester yarn packages is in its sixth year within the College of Textiles at North Carolina State University. Process development has been accomplished using a single-package SC-CO2 dyeing machine located in the Model Manufacturing Facility of the College. This paper provides an overview of the status of the research and discusses the technical and economic factors important to the successful commercialization of an SC-CO2 polyester yarn package dyeing process.
Computational Analysis for the Torsional Vibration Control of an Anti-Symmetric Piezoelectric Composite Laminate
Authors: Lee Shi-Wei Ricky , Li Hing Leung
Published: July 2008

The present paper demonstrates an effort to control the torsional vibration of a piezo electric composite laminate using its intrinsic structural coupling effect. The sensor and actuator were built-in to the structure. The signal from the sensor was directly fed into the actuator without modification except amplification. Various sensor-actuator configurations were investigated and a characteristic damping time was employed to evaluate the effectiveness of torsional vibration control. Certain interesting structural behaviors were observed and the optimal configuration was identified.
Thermomechanical Properties of Polyurethane-Shape Memory Polymer Foam
Authors: Tobushi H. , Okumura K. , Endo M. , Hayashi S.
Published: July 2008

The thermomechanical properties of polyurethane-shape memory polymer foam were investigated by the compressive tests. The results are summarized as follows. (1) The material contracts uniformly in the axial direction with the ratio of lateral strain to axial strain 0.4 in the early stage, but about 0.15 thereafter. (2) The deformation resistance is large at low temperature and at high strain rate. (3) In the case of thermomechanical loading, strain is recovered at temperatures in the vicinity of Tg. The rate of strain recovery is 99%. The rate of strain fixity is 100%.
Miniature Free-Fall Sensors
Authors: Hsu Yu-Hsiang , Lee Chih-Kung
Published: July 2008

This paper describes an attempt to integrate the smart structure concept to the field of high-density data storage devices such as magnetic disk drives, optical disk drives, CDs (compact disks), and DVDs (digital versatile disks), etc. With the rapid development of the data storage industry, methodologies that can be used to sense vibration, free-fall, and impact have been actively pursued throughout the last two decades. As data storage devices are now moving into portable applications, early detection of impact or free-fall has increasingly become more important. Based on this major issue, the concept of measuring the motion of the required free-fall is re-examined. In this article, it is shown that a fundamental characteristic of a free-fall motion, which is the acceleration from zero to one in gravity unit, will be introduced to provide the warning signal for data storage devices. The design concept and the experimental result of this miniature free-fall sensor will be detailed.
Piezoelectric Transverse Shear Actuation and Sensing of Plates, Part 2: Application and Analysis
Authors: Benjeddou A. , Deu J.-F.
Published: July 2008

An exact three-dimensional mixed state space formulation has been presented in Part 1 of this paper for the piezoelectric transverse shear actuation and sensing of plates. In this second part, its application to three-layer adaptive plates with piezoceramic core is studied theoretically and numerically for validation purpose. Then, a detailed parametric analysis is conducted to investigate the influence of several parameters such as, the plate thickness ratio, the piezoceramic core thickness, the mechanical and electric loading amplitudes, and the piezoceramic sensor/actuator position through a multilayer cross-ply hybrid laminate. It was found that, to represent both sensing and actuation behaviors, mechanical in-plane displacements and transverse deflection should be taken layerwise linear (in “zig-zag”) and constant through the plate thickness, respectively. The electric potential was found always linear inside the piezoceramic layer. Variation of the piezoceramic core thickness did not affect much the distributions patterns. However, the induced plate voltage and center deflection under varied mechanical and electric loading amplitudes were found to be proportional to the applied mechanical load and actuation voltage. The optimum position of the piezoceramic transverse shear sensor/actuator through-the-thickness of a multilayer cross-ply hybrid plate was found to be at its mid-plane. These results are useful for future reference and comparison with other approximate analytic and numerical solutions. They can also be used to construct such two-dimensional models.