Continuum robot-based surgical systems are becoming an effective tool for minimally invasive surgery. A flexible, dexterous, and compact robot structure is suitable for carrying out complex surgical operations. In this paper, we propose performance metrics for dexterity based on data density. Data density at a point in the workspace is higher if the number of reachable points is higher, with a unique configuration lying in a small square box around a point. The computation of these metrics is performed with forward kinematics using the Monte Carlo method and, hence, is computationally efficient. The data density at a particular point is a measure of dexterity at that point. In contrast, the dexterity distribution property index is a measure of how well dexterity is distributed across the workspace according to desired criteria. We compare the dexterity distribution property index across the workspace with the dexterity index based on the dexterous solid angle and manipulability-based approach. A comparative study reveals that the proposed method is simple and straightforward because it uses only the position of the reachable point as the input parameter. The method can quantify and compare the performance of different geometric designs of hyper-redundant and multisegment continuum robots based on dexterity.

The present study was conducted to elucidate (1) the influence of kisspeptin (KP) on the in vitro development of preantral follicles (PFs) and (2) evolution of KP receptor gene (KISS1R) expression during ovarian follicular development in sheep. Kisspeptin was supplemented (0–100 µg/ml) in the culture medium of PFs for 6 days. The cumulus–oocyte complexes (COCs) from cultured PFs were subsequently matured to metaphase II (MII) for an additional 24 h. The proportions of PFs exhibiting growth, antrum formation, average increase in diameter, and maturation of oocytes to MII stage were the indicators of follicular development in vitro. The expression of the kisspeptin receptor gene at each development stages of in vivo developed (preantral, early antral, antral, large antral and COCs from Graafian follicles) and in vitro cultured PFs supplemented with KP was assessed using a real-time polymerase chain reaction. The best development in all the parameters under study was elicited with 10 µg/ml of KP. Supplementation of KP (10 µg/ml) in a medium containing other growth factors (insulin-like growth factor-I) and hormones (growth hormone, thyroxine, follicle-stimulating hormone) resulted in better PF development. The KISS1R gene was expressed in follicular cells and oocytes at all the development stages of both in vivo developed and in vitro cultured follicles. Higher KISS1R gene expression was supported by culture medium containing KP along with other hormones and growth factors. Accordingly, it is suggested that one of the mechanisms through which KP and other growth factors and hormones influence the ovarian follicular development in mammals is through the upregulation of expression of the KP receptor gene.

This paper presents a study on the effect of design parameters of an underactuated hand on its grasp performance. Three kinds of grasp performance characteristics are considered: grasp range, grasp strength, and immobilizing grasp range. Grasp strength is defined as the stiffness of the grasp. Immobilizing grasps are those in which the object cannot be moved for a force up to a certain threshold. In general, underactuated hands cannot produce immobilizing grasps. However, we show that immobilizing grasps can be created by including joint limits in the hand design. We consider the effect of two design parameters on the grasp performance: torque ratio and finger-base distance. Results show that an optimal finger-base distance and torque ratio exists that maximizes the grasp range and grasp strength. Also, the immobilizing grasp range is increased by decreasing the finger-base distance and increasing the torque ratio and joint limits.

With many micromanipulator designs emerging in micro and nanosystem applications, the element of compliance in the mechanisms is gaining attention. Several designs consider motions limited in a plane for high accuracy and repeatability as needed in micro/nano manipulation applications. Extending this to a full spatial configuration with coupled motions of series and parallel linkages with flexure joints of 1-degree-of-freedom (DOF) and 3-DOF needs a systematic analytical approach. One such approach for compliance analysis is presented in this article for a mechanism designed at Indian Institute of Technology Kharagpur. To validate the analytical models, finite element analysis simulations are performed with the help of the Abaqus-6.14 software package. Following the successful validation, the effect of structural parameters on the performance is presented with the help of the analytical expressions. We explore the performance of the mechanism with different dimensions of flexures of a particular type. Results indicate that the design with dissimilar dimensional parameters can give superior performance.

Forage sorghum is an important component of the fodder supply chain in the arid and semi-arid regions of the world because of its high productivity, ability to utilize water efficiently and adaptability to a wide range of climatic conditions. Identification of high-yielding stable genotypes (G) across environments (E) is challenging because of the complex G × E interactions (GEI). In the present study, the performance of 16 forage sorghum genotypes over seven locations across the rainy seasons of 2010 and 2011 was investigated using GGE biplot analysis. Analysis of variance revealed the existence of significant GEI for fodder yield and all eight associated phenotypic traits. Location accounted for a higher proportion of the variation (0·72–0·91), while genotype contributed only 0·06–0·21 of total variation in different traits. Genotype-by-location interactions contributed 0·02–0·13 of total variation. Promising genotypes for fodder yield and each of the associated traits could be identified effectively using a graphical biplot approach. The majority of test locations were highly correlated. A ‘Which-won-where’ study partitioned the test locations into two mega-environments (MEs): ME1 was represented by five locations with COFS 29 as the best genotype, while ME2 had two locations with S 541 as the best genotype. The existence of two MEs suggested a need for location-specific breeding. Genotype-by-trait biplots indicated that improvement for forage yield could be achieved through indirect selection for plant height, leaf number and early vigour.

Poly(vinyl alcohol) (PVA) is a synthetic polymer which has been used in a wide variety of applications. This polymer has been extensively investigated by a large number of techniques to shed light about its physical and chemical properties. In this work, for fist time, high frequency (1x109-3x109 Hz) relaxation process has been observed in the PVA films in the temperature range of -100C to +1200C. This relaxation exhibits negative activation energy below glass transition temperature Tg and at higher temperature positive activation energy with subsequent saturation. Upon cooling the activation energy was negative again. This high frequency relaxation process and its temperature dependence can be attributed to the interaction of the bounded water and the changes of energy and freedom of movement of OH side molecular chains groups. This conclusion has been supported by in situ FTIR measurements. A possible scenario of this relaxation and dynamics of molecular motion has been proposed.

A compact slot antenna for high-gain ultra wideband applications is presented. The slot is asymmetrically cut in the ground plane and is a combination of two rectangles. A hexagonal patch with two stepped coplanar waveguide-feed is used to excite the slot. The capacitive reactance of the hexagonal patch is neutralized by the inductive reactance created by the asymmetric slot and results into wider impedance matching. The measured impedance bandwidth of the proposed antenna is 11.85 GHz (2.9–14.75 GHz). The radiation patterns of the proposed antenna are found to be omni-directional in the H-plane and bi-directional in the E-plane. To enhance the gain of the antenna, a compact three-layer frequency selective surface (FSS) is used as a reflector. The overall thickness of the FSS is 3.5 mm. There is 4–5 dBi improvement in antenna gain after application of the FSS. The measured and simulated results are in good agreement.

The molecular relaxations behavior of chitosan (CS) films in the wide frequency range of 0.1-3x109 Hz (by using three different impedance analyzers) have been investigated in the temperature range of -100C to 120°C using Dielectric Spectroscopy (DS). Additionally to the low frequency molecular relaxations such as α and β relaxations, for the first time, high frequency (1-3 GHz) relaxation process has been observed in the chitosan films. This relaxation exhibits Arrhenius-type dependence in the temperature range of -100 C to 54°C with negative activation energy -2.7 kJ/mol. At temperatures above 54°C, the activation energy changes from -2.7 kJ/mol to +4.4 kJ/mol. Upon cooling, the activation energy becomes negative again with a value of -1.2 kJ/mol. The bound water between chitosan molecules strongly modifies molecular motion and the relaxation spectrum, giving rise to a new relaxation at the frequency at ca. 1 GHz. In situ FTIR analysis has shown that this relaxation related to the changes in vibration of the –OH, NH and –CO functional groups.

Sedimentary carbonate rocks are one of the principal porous structures in natural reservoirs of hydrocarbons such as crude oil and natural gas. Efficient hydrocarbon recovery requires an understanding of the carbonate pore structure, but the nature of sedimentary carbonate rock formation and the toughness of the material make proper analysis difficult. In this study, a novel preparation method was used on a dolomitic carbonate sample, and selected regions were then serially sectioned and imaged by focused ion beam–scanning electron microscopy. The resulting series of images were used to construct detailed three-dimensional representations of the microscopic pore spaces and analyze them quantitatively. We show for the first time the presence of nanometer-scale pores (50–300 nm) inside the solid dolomite matrix. We also show the degree of connectivity of these pores with micron-scale pores (2–5 μm) that were observed to further link with bulk pores outside the matrix.

Waspaloy specimens aged at 800°C from 0.5h to 88.5h were evaluated via small angle neutron scattering (SANS), ultra small angle X-ray scattering (USAXS), electrical resistivity, and SEM. The average γ' precipitate size and volume fraction, obtained from modeling the small angle scattering data, was used to calculate a figure of merit of electron scattering. This figure of merit is designed to correlate the electron scattering ability of the material to the precipitate microstructure. The USAXS data shows a secondary precipitate population at smaller diameters that is absent from the SANS data, since the SANS measurements were not obtained at high enough values of Q. It is believed that this secondary population makes the USAXS-derived figure of merit more sensitive to the actual measured resistivity response than the SANS-derived values; however, the SANS derived primary precipitate sizes are believed to more accurate due to a larger sample volume.

The results of SPM-based localized electrical examination of precipitation hardened Waspaloy microstructures using Electrostatic Force Microscopy (EFM) and Current-Atomic Force Microscopy (I-AFM) are reported herein. The measurements were conducted on two differently etched specimens with the same initial microstructure. Selective etching by preferentially removing the γ′ or the γ phase resulted in a non-uniform surface topography leaving the less reactive phase standing in relief relative to the depressed phase. The presence of a non-uniform surface topography affected the measured EFM response by causing an inhomogeneous surface voltage distribution. A non-linear tip-surface interaction could have further complicated the measured EFM response by making it non-localized. The EFM phase obeyed a supplementary behavior upon reversing the polarity of the DC bias. Using I-AFM, the tip current was found to be the highest at γ-γ′ interphase boundaries, which was attributed to the relaxation of the lattice atoms in the relief zone formed upon etching.

Nickel-base superalloys are an important class of metallic ‘nanocomposite’ structural materials known for their good strength retention abilities at high homologous temperatures for long service times. Literature on electrical resistivity studies of age-hardening superalloys is limited. The current work is focused on developing microstructure-electrical resistivity correlations in controlled Waspaloy microstructures. The microstructures are ‘controlled’ as the size distribution of g¢ precipitates is varied systematically. The microstructures are produced upon aging the initial homogenized alloy at nominal temperatures of 700°C, 800°C and 875°C for times up to 100 hrs. Resistivity measurements did not reveal a g¢ nucleation regime for the sampled aging intervals. The primary microstructural evolution mechanism contributing to the observed changes in resistivity was g¢ coarsening. Interestingly, the microstructures resulting from progressive aging at 700°C showed a slow transformation of etch-pits from perfect polygonal shapes to more irregular shapes.

Aluminum nitride (AlN), a wide band gap semiconductor (Eg = 6.2eV), has potential applications in microelectronics due to its excellent insulating properties and compatibility with silicon [1,2]. More recently, the use of AlN thin films in high electron mobility transistors, light emitting diodes and UV sources is explored by altering the band gap of the material [3]. The present work describes the combinatorial synthesis of (Al,Ti)N thin films via pulsed laser deposition (PLD) technique to obtain desirable compositional spreads and corresponding variations in the electrical properties. Films of AlN, TiN and (Al,Ti)N were deposited on 6H-SiC (0001) substrates held at a temperature of 680°C. The surface quality of the films examined using an AFM revealed island growth of SiO2 and other growth patterns possibly related to substrate defects.

X-ray diffraction studies indicated that the growth of AlN and TiN films occurred with corresponding habit planes of (0002) and (111) parallel to the substrate surface. Compositional investigations conducted using energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) showed systematic changes in the Al and Ti composition across the thickness of the compositional spread film. Cross-sectional analysis of (Al,Ti)N films conducted in a high-resolution transmission electron microscope revealed that the films were multi-layered. Several orders of magnitude decrease in the measured resistivity across a 15 mm length (Al,Ti)N film was noted corresponding to a systematic increase in the Ti content. Further optimization of deposition conditions is essential for producing thicker films.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Radiation resistant ferrite materials have potential applications in space station. Mg-Mn spinel ferrite was choosen for this study because of its radiation resistance and potential for use as an insulator in radiation environments. The radiation damage expected in these environments can be quickly and conveniently simulated using ion irradiation. The results of swift heavy ion irradiation induced modifications in the magnetization behavior of the Mg-Mn ferrite nanoparticles have been investigated using 100 MeV Ni8+ ion irradiation. To ensure the singlephase spinel structure of the system powder x-ray diffraction patterns has been performed. The powder samples were irradiated at three different fluences in the range 1×1012-5×1013 ions/cm2. Isothermal dc magnetization studies have been performed using SQUID and vibration sample magnetometer (VSM) on the pristine as well as on the irradiated samples at 20 K and 300 K. With irradiation saturation magnetization remains almost constant with ions irradiation. The coercivity values of the materials decreased about 5% with the fluence 1×1013 ions/cm2 as compare to the pristine nanoparticles. The results have been explained on the basis of the existence of surface defects produced by swift heavy ions, which generate orientational disorder of surface spins. The behavior of saturation magnetization with irradiations makes these nanoparticles suitable for memory devices in the space research.

It has been shown recently that the short channel performance worsens for high-K dielectric MOSFETs as the physical thickness to the channel length ratio increases, even when the effective oxide thickness (EOT) is kept identical to that of SiO2. In this work we have systematically evaluated the effective dielectric thickness for different Kgate to achieve targeted threshold voltage (Vt), drain-induced barrier lowering (DIBL) and Ion/Ioff ratio for different technology generations down to 50 nm using 2-Dimensional process and device simulations. Our results clearly show that the oxide thickness scaling for high-K gate dielectrics and SiO2 follow different trends and the fringing field effects must be taken into account for estimation of effective dielectric thickness when SiO2 is replaced by a high-K dielectric.

This paper presents a framework and a prototype for designing Integrated Construction Management (ICM) software applications using reusable components. The framework supports the collaborative development of ICM software applications by a group of ICM application developers from a library of software components. The framework focuses on the use of an explicit software development process to capture and disseminate specialized knowledge that augments the description of the ICM software application components in a library. The importance of preserving and using this knowledge has become apparent with the recent trend of combining the software development process with the software application code. There are three main components in the framework: design patterns, design rationale model, and intelligent search algorithms. Design patterns have been chosen to represent, record, and reuse the recurring design structures and associated design experience in object-oriented software development. The Design Recommendation and Intent Model (DRIM) was extended in the current research effort to capture the specific implementation of reusable software components. DRIM provides a method by which design rationale from multiple ICM application designers can be partially generated, stored, and later retrieved by a computer system. To address the issues of retrieval, the paper presents a unique representation of a software component, and a search mechanism based on Reggia's setcover algorithm to retrieve a set of components that can be combined to get the required functionality is presented. This paper also details an initial, proof-of-concept prototype based on the framework. By supporting nonobtrusive capture as well as effective access of vital design rationale information regarding the ICM application development process, the framework described in this paper is expected to provide a strong information base for designing ICM software.