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The steric properties of the tetradentate ligand influences the reactivities of the Fe(v)O units in a number of tautomeric Fe(v)(O)(OH) complexes.

The main objective of this article is to introduce a fixed-point result involving two mappings satisfying contraction in a metric-like space. The article has been designed in the following manner. In the first section the authors have mentioned some definitions and commonly used notations. In the second section, they have mentioned some fixed-point results. In the third section the authors have introduced their main result and in the last section, using these results, the authors have obtained some conditions that assure the existence of a common fixed point of a pair of mappings.

Basaltic reservoirs have produced hydrocarbon from Yurihara Field in Japan, Quiko Depression in China, and Padra Field of Cambay Basin and Western Offshore Basin in India. The availability of fractured, altered, and vesicular basalts contributes to reservoir development in this stratigraphic unit. This study is conducted in the Kutch-Saurashtra Basin, located at the western continental margin of the Indian subcontinent wherein, the Deccan basalt, with a thickness range of 200–2500 m, overlies Mesozoic sediments. The Jurassic and Cretaceous sediments constitute the main source rock in the area. Several wells have been drilled through the entire basalt section, and some are hydrocarbon bearing in basalt. The entire basalt section in the study area has been classified into four major units using gamma-ray logs. These units have been further subdivided into individual flows and correlated all over the basin. Analysis shows that the base of an individual basalt flow is massive, and the top is differentially altered. Crossplot analysis of P-impedance and VP/VS ratio carried out on logs delineates a zone of moderately weathered/altered basalt, which is due to spheroidal weathering and calibrated with sidewall cores. These moderately altered zones between two successive flows of basalt are the probable reservoir facies for hydrocarbon accumulation, provided that there is an overlying seal in the form of massive or completely altered basalt. Three-dimensional seismic data in the area show an alternating reflection pattern in the basalt section due to the alternation of massive and weathered basalt. The seismic signature of basalt in the area is similar to that of a sedimentary sequence in any given area. Continuity of the identified individual flows in seismic scale has been propagated over the entire seismic, and subsequent inversion has facilitated the deciphering of the probable hydrocarbon-bearing locales within basalt.

A dinuclear copper(II) complex [Cu2(papy)2(CH3OH)2] has been synthesized by reaction of one equiv. of Cu(OAc)2·2H2O with one equiv. of the tetradentate tripodal ligand H2papy [N-(2-hydroxybenzyl)-N-(2-picolyl)glycine] and has been characterized by various spectroscopic techniques and its solid state structure has been confirmed by X-ray crystal structure analysis. The single-crystal structure of the complex reveals that the two copper centers are hexa-coordinated and bridged by two O-atoms of the phenoxo moieties. The variable temperature magnetic susceptibility measurement of the complex reveals weak ferromagnetic interactions among the Cu(II) ions with a J value of 1.1 cm−1. The catecholase activity of the complex has been investigated spectrophotometrically using 3,5-di-tert-butyl catechol as a model substrate in methanol solvent under aerobic conditions. The Michaelis–Menten kinetic treatment has been applied using different excess substrate concentrations. The parameters obtained from the catecholase activity by the complex are KM 2.97 × 10−4 M, Vmax 2 × 10−4 M s−1, and kcat 7.2 × 103 h−1. A reaction mechanism has been proposed based on experimental findings and theoretical calculations. The catechol substrate binds to dicopper(II) centers and subsequently two electrons are transferred to the metal centers from the substrate. The bridging phenoxo moieties participate as a Bronsted base by accepting protons from catechol during the catalytic cycle and thereby facilitating the catechol oxidation process.

Aim: We present a touch-activated, sanitizer dispensing (TSD) device, intended to be mounted on high-touch surfaces, that aims to reduce nosocomial infections. It disinfects the person’s hand touching its surface while being self-sterilizing. Materials & methods: The TSD device consists of an array of 3D-printed, passive, miniaturized, mechanical valves that dispense a small amount of liquid sanitizer when touched. Its mechanical performance and disinfecting efficiency were quantified using simulations and experimental tests. Results & conclusion: The TSD device has a disinfecting efficiency comparable to the standard hand sanitizing approach, reducing the microbiological load by approximately 30-times. It can be easily mounted on high-touch surfaces in a healthcare setting and it is expected to greatly reduce the spread of nosocomial infections.

Mucin 4 (MUC4) and matrix metalloproteinase 7 (MMP7) have been reported to be associated with chronic periodontitis as seen in gingival tissue biopsies. Therefore, it is of interest to estimate the levels of MUC4 and MMP7 in saliva and gingival crevicular fluid (GCF) samples of periodontitis in adolescents patients at West Bengal, India. MUC4 levels were significantly lower in saliva and GCF from periodontitis patients compared to healthy controls. However, MMP7 levels were found to be significantly higher in saliva and GCF from periodontitis patients. Thus, MUC4 and MMP7 are biomarkers for periodontitis diagnosis and towards further consideration.

Many important engineering structures such as rotating machinery, including turbine bladed disks, gears, flywheels and satellites are comprised of repeated (nominally identical) substructures arranged circumferentially with cyclic symmetry. Due to this unique arrangement, the system matrices and consequently the dynamics of such structures exhibit specific characteristics (Mitra and Epureanu, ASME Appl Mech Rev. https://doi.org/10.1115/1.4043083, 2019; Olson et al. ASME Appl Mech Rev, 66(4):040803, 2014). Extensive scientific study and analysis has been conducted on this topic in recent decades. Of particular interest is the change in dynamic behavior when there are deviations in substructures from their nominal, even to a small extent. Colloquially termed mistuning, such deviations are practically impossible to avoid. They manifest as material or geometric differences due to causes such as manufacturing tolerances, wear and differential operation conditions (Castanier and Pierre, J Propuls Power 22/2:384, 2006). Mistuning can lead to strain energy localization, higher system responses and reduction of the operational life cycle and should therefore be carefully considered in the design and analysis of structures. The current industrial practice is to use Monte Carlo simulations to characterize mistuning effects using randomly generated deviations in substructures of the nominal design (Mitra and Epureanu, ASME Appl Mech Rev. https://doi.org/10.1115/1.4043083, 2019; Castanier and Pierre, J Propuls Power 22/2:384, 2006). Since thousands of dynamic simulations might be required to characterize a single design, full order high fidelity models remain prohibitively expensive. For such tasks, reduced order models (ROMs) are employed instead (Castanier and Pierre, J Propuls Power 22/2:384, 2006; Baek and Epureanu, ASME J Vib Acoust, 139(6):061011, 2017). However, obtaining fast and accurate ROMs for cyclic structures with nonlinearities (Mitra and Epureanu, ASME Appl Mech Rev. https://doi.org/10.1115/1.4043083, 2019; Baek and Epureanu, ASME J Vib Acoust, 139(6):061011, 2017; Zucca and Firrone, J Sound Vib, 333:916–926, 2014) remains a challenging task. This tutorial aims at summarizing and highlighting some of the most relevant techniques that have been proposed to date, with a specific focus on nonlinear ROMs including contact nonlinearities.

Cotton yarns were modified with pyrrole in the presence of ferric chloride following a dip-nip-dry technique. Treatment of cotton with 23.4% aqueous pyrrole followed by treatment with 40.6% aqueous ferric chloride and subsequent drying in atmospheric air produced balanced improvements in the properties of the yarn such as conductivity, tensile strength and extensibility. Among the three types of yarns such as ring spun, rotor spun and friction spun considered for such treatment, ring spun yarn performed best in respect of conductivity and retention of strength. Examination of surface morphology of yarns by scanning electron microscopy revealed a common discontinuity in the growth of polypyrrole along the length of the yarns spun using friction spinning and rotor spinning systems. Such discontinuity was caused by the wrapper fibres. Ring spun yarn, on the other hand, allowed a continuous spiral growth and deposition of polypyrrole in the inter-fibre space and on the surface of the yarn. Study of py...

The selective catalytic functionalization of hydrocarbons under mild conditions is a subject of considerable current interest. While selective oxidations of C H bonds remain a challenging task to the synthetic chemists, Nature provides several successful solutions to this by utilizing remarkably efficient biocatalysts, namely the oxygenases. Iron-containing oxygenases with heme or nonheme active sites participate in biologically important oxidative transformation reactions by dioxygen activation. The transient high-valent iron-oxo species thus generated are proposed to be the key reactive intermediates in the oxidation reactions and have been detected in several occasions. Inspired by the Nature, rational design of synthetic analogues of iron oxygenases paves the way for the development of efficient catalysts for selective C H bond oxidation. This review focuses on the significant advances made in the catalytic oxidations of hydrocarbons by different nonheme mono- and dinuclear iron complexes over past three decades with a highlight on the mechanistic aspects and addresses the forthcoming challenges in this field.

The oxidation reactions of alkanes with hydrogen peroxide and peracids (peracetic acid (PAA) and m-chloroperoxybenzoic acid (mCPBA)) catalysed by two Fe(II) complexes of pentadentate {N5}-donor ligands have been investigated. Kinetic isotope effect experiments and the use of other mechanistic probes have also been performed. While the total yields of oxidized products are similar regardless of oxidant (e.g. 30–39% for oxidation of cyclohexane), the observed alcohol/ketone ratios and kinetic isotope effects differ significantly with different oxidants. Catalytic reactions in H2O2 medium are consistent with the involvement of hydroxyl radicals in the Csingle bondH bond cleavage step, and resultant low kinetic isotope effect values. On the other hand, catalytic reactions performed using peracid media indicate the involvement of an oxidant different from the hydroxyl radical. For these reactions, the kinetic isotope effect values are relatively high (within a range of 4.2–5.1) and the C3/C2 selectivity parameters in adamantane oxidation are greater than 11, thereby excluding the presence of hydroxyl radicals in the Csingle bondH bond cleavage step. A low spin Fe(III)-OOH species has been detected in the H2O2-based catalytic system by UV/Vis, mass spectrometry and EPR spectroscopy, while an Fe(IV)-oxo species is postulated to be the active oxidant in the peracid-based catalytic systems. Computational studies on the Csingle bondH oxidation mechanism reveal that while the hydroxyl radical is mainly responsible for the H-atom abstraction in the H2O2-based catalytic system, it is the Fe(IV)-oxo species that abstracts the H-atom from the substrate in the peracid-based catalytic systems, in agreement with the experimental observations. (Less)

We investigate the dynamics of a delay differential coupled Duffing-Van der Pol oscillator equation. Using the Lindstedt's method, we derive the in-phase mode solutions and then obtain the slow flow equations governing the stability of the in-phase mode by employing the two variable perturbation method. We solve the slow flow equations using series expansion and obtain conditions for Hopf bifurcation and studied stability of the in-phase mode. Finally, we studied stability and bifurcations of the origin. Our interest in this system is due to the fact that it is related to the coupled laser oscillators.

In this study, a novel design for ring dampers is proposed, where the concept of tuned vibration absorbers is leveraged to substantially increase damper effectiveness while minimizing potential stresses near the blade root. Tuned absorbers have been used in the past to reduce the forced response amplitudes of both mechanical and civil structures. The absorber natural frequency is tuned to the targeted frequency of the host structure where it is attached. The vibration reduction mechanism relies on energy transfer from the host structure to the absorber. The novel design technique proposed here uses a vibration absorber approach to achieve energy transfer from the blisk to the damper, which leads to larger damper motion. This enables energy dissipation due to friction, reducing vibrations even in blade dominated modes. An academic finite element model of a blisk with a ring damper is used to demonstrate the novel tuned damper concept and design technique. The geometric mistuning of the damper due to the presence of a gap in the ring structure is also taken into account. The results demonstrate the validity of the proposed tuned damper concept, showing a substantial vibration amplitude reduction compared to the linear baseline results, in which the damper is not tuned or absent.

Turbine bladed disks or blisks, which constitute critical components of most modern turbomachinery, are known for their complex vibratory behavior. The nonlinear dynamics observed in most operational regimes of blisk with contact interfaces are dominated by one of two typical contact behaviors. Frictional contacts are dominated by Coulomb friction forces, while intermittent contacts are characterized by multiple separation events. Other factors such as the dispersion in material or geometric properties across blades, known as mistuning, also affect the dynamics significantly. Presently, probabilistic analysis is the widely accepted design methodology to account for mistuning, which is unknown prior to manufacture. Thus, reduced order modeling of these blisks is essential as high fidelity models are prohibitively expensive for such simulations. This paper provides a technical discussion of dynamic modeling and reviews projection-based techniques used for creation of reduced models of blisks with contacts.

The vibration absorber or tuned mass damper is a well-known mechanism, where a small mass connected to a larger structure is used to redirect vibration energy and provide reduction in vibration amplitudes at desired locations and frequencies. While tuned vibration absorbers have been widely applied for damping of mechanical systems, the concept remains largely unexplored in the design of dampers for bladed disks. This paper investigates whether such a vibration absorption mechanism is feasible for such nominally cyclic symmetric structures which are characterized by double modes, high modal density, and sensitivity to uncertainties such as mistuning. The single-degree of freedom vibration absorber concept is extended for application to this complex modal space, and lumped mass models are used for analysis. Trends in effectiveness of a vibration absorption based damper are explored by studying sensitivities to various parameters such as stiffness and damping at various locations. Effects of mistuning across sectors and locations of damper attachment are also considered. The results of the study establish the feasibility of the vibration absorption mechanism for application in blisks, and encourage further exploration of the concept, possibly in conjunction with other well-established damping mechanisms such as friction.

The chiral tetradentate N4-donor ligand, 1-methyl-2-({(S)-2-[(S)-1-(1-methylbenzimidazol-2-yl methyl)pyrrolidin-2-yl]pyrrolidin-1-yl}methyl) benzimidazole (S,S-PDBzL), based on a chiral dipyrrolidine backbone, has been synthesized and its corresponding Fe(ii) complex has been prepared and characterized. The X-ray structure of the complex reveals that the Fe(ii) ion is in a distorted octahedral coordination environment with two cis-oriented coordination sites occupied by (labile) triflate anions. The ability of the iron complex to catalyze asymmetric epoxidation reactions of olefins with H2O2 was investigated, using 2-cyclohexen-1-one, 2-cyclopenten-1-one, cis-β-methylstyrene, isophorone, chalcones and tetralones as substrates. Different carboxylic acids were used as additives to enhance yields and enantioselectivities, and 2-ethylhexanoic acid was found to give the best results. The catalysis results indicate that the Fe(ii) complex is capable of effecting comparatively high enantioselectivities (80%) in the epoxidation reactions.

A new and relatively simple synthetic strategy has been described for Pd(II)-catalyzed C-C bond formation via alkylation of ortho C(sp2)-H bonds in substituted azobenzenes possessing (2-phenylamino)phenylazo directing group employing different alkyl iodides. The yields of various ortho alkylated products are found to be good to excellent (65-85%). A palladocyclic intermediate complex has been isolated and fully characterized. Based on the experimental results and the isolation of the palladocyclic intermediate, a catalytic cycle involving a sequential C-H activation/oxidative addition followed by reductive elimination pathway has been proposed.

In this paper, a reduced order model is developed to simulate the dynamics of a bladed disk or blisk with nonlinear damping coatings adhered to its blades. The nonlinear forces exerted by these coatings on the underlying linear blisk structure are a function of the local strain. It is known that coatings modify the stiffness and damping of each blade depending on its amplitude. Blisks, which are designed as perfectly cyclic symmetric structures with identical blades, never behave as such in practice due to various uncertainties encountered during their manufacturing. This asymmetry in the structure is also referred to as mistuning. Mistuning in the linear blisk structure, which causes different blades to respond with non-identical amplitudes, interacts with the coating nonlinearity to yield a mistuning pattern which depends on the blade amplitudes. Additional stiffness and damping parameters that are dependent on the blade amplitude are introduced into a reduced linear model to formulate the nonlinear reduced order model. It is found that this model captures the nonlinear amplitude dependent mistuning effect and predicts the nonlinear coated blisk responses accurately near isolated blisk mode families in blade-dominated frequency regions where these coating effects are likely to be dominant. Significant reductions in the computational effort are achieved through this reduction.

The chiral tetradentate N4-donor ligand, 1-methyl-2-({(S)-2-[(S)-1-(1-methylbenzimidazol-2-yl methyl)pyrrolidin-2-yl]pyrrolidin-1-yl}methyl) benzimidazole (S,S-PDBzL), based on a chiral dipyrrolidine backbone, has been synthesized and its corresponding Fe(II) complex has been prepared and characterized. The X-ray structure of the complex reveals that the Fe(II) ion is in a distorted octahedral coordination environment with two cis-oriented coordination sites occupied by (labile) triflate anions. The ability of the iron complex to catalyze asymmetric epoxidation reactions of olefins with H2O2 was investigated, using 2-cyclohexen-1-one, 2-cyclopenten-1-one, cis-β-methylstyrene, isophorone, chalcones and tetralones as substrates. Different carboxylic acids were used as additives to enhance yields and enantioselectivities, and 2-ethylhexanoic acid was found to give the best results. The catalysis results indicate that the Fe(II) complex is capable of effecting comparatively high enantioselectivities (>80%) in the epoxidation reactions The research has been carried out within the frameworks of the International Research Training Group Metal sites in biomolecules: structures, regulation and mechanisms (http://www.biometals.eu), the Marie Sklodowska-Curie Innovative Training Network MSCAITN-2015-ETN 675020 and COST Action CM1003. M. M. thanks the European Commission for an Erasmus Mundus fellowship

A new mononuclear homoleptic chromium complex has been synthesized by reaction of one equiv. of Cr(CO)6 with two equiv. of the azoaromatic pincer ligand namely 2,6-bis[(4-methylphenyl)azo]pyridine [LMe] in n-octane under reflux condition. The complex has been fully characterized by ESI-MS, 1H-NMR, FT-IR and UV/Vis spectroscopy. The X-ray structure of the complex reveals that the Cr-metal is coordinated to the central pyridine N-atom and two azo N-atoms of each tridentate pincer ligand in an octahedral environment. The 1H-NMR spectrum of the complex is indicative of diamagnetic ground state. The elongation of N-N bond lengths [d(N-N)av = 1.3275 A] in the complex is consistent with the presence of azo-anion-radical character in the ligand. Since 2,6-bis(phenylazo)pyridine and its 4-Me-derivative are redox non-innocence in nature and therefore can coordinate to the chromium metal center as neutral (L0) or as mono-anionic mono-radical (L·)1− or as di-anionic di-radical (L··)2- or even as tri-anionic mono-radical (L·)3− resulting an ambiguity on the true oxidation state of the metal center. Thus the present work nicely elaborates the importance of suitably designed bis-azopyridine containing pincer ligand in accessing an air-stable Cr(II) complex starting with low-valent metal carbonyl precursor via electron transfer from the metal center to the highly π-acidic ligand leading to stable azo-anion-radicals. The stability of azo-anion-radical bound Cr(II) complex has been investigated by DFT calculations.

A new iron complex mediates stereospecific hydroxylation of alkyl C-H bonds with hydrogen peroxide, exhibiting excellent efficiency. Isotope labelling studies provide evidence that the relative reactivity of tautomerically related oxo-iron species responsible for the C-H hydroxylation reaction is dominated by steric factors This work has been supported by the European Union (the Erasmus Mundus program), the International Research Training Group Metal Sites in Biomolecules: Structures, Regulation and Mechanisms (www.biometals.eu), and COST Action CM1003. M.C. acknowledges ERC-29910, MINECO of Spain for CTQ2012- 37420-C02-01/BQU and CSD2010-00065, catalan DIUE (2009SGR637) and an ICREA academia award. J.Ll. thanks MICINN for a RyC contract

This paper investigates methodologies for finding optimal or near-optimal blade arrangements in a bladed disk with inserted blades for minimizing or maximizing blade response amplification due to mistuning in material properties of the blades. The mistuning in the blades is considered to be known, and only their arrangement is modifiable. Hence, this is a problem in discrete optimization, particularly combinatorial optimization where the objective of response amplification is a nonlinear function of the blade arrangement. Previous studies have treated mistuning as a continuous parameter to analyze its effects on the response amplification. Sensitivity metrics have proven to be an important tool in quantifying the effects of mistuning. One such sensitivity metric is used here to formulate an iterative heuristic approach to solve the optimization problem. A component mode mistuning reduced order model is used for fast evaluations of the dynamic responses of a bladed disk with a given blade arrangement. At any iteration the sensitivity of the maximum response of the current rotor design to changes in blade stiffnesses due to changes in the blade arrangement is used to predict the arrangement for the following iteration. In addition to the proposed sensitivity-based approach, we use genetic algorithms to find optimal arrangements and compare results with the heuristic approach.

This paper develops a novel form of a well-known signal processing technique, so as to be applicable to the interaction between a heavy truck and a supporting bridge structure. Motivated by the problem of structural health monitoring of bridges, a new modal coherency function is defined. This relates the input action of moving wheel loads to the dynamic response of the bridge, including the effects of unevenness of the road surface and the vertical dynamics of the truck suspension. The analysis here is specifically aimed at future experimental testing – the validation of axle load estimators obtained from sensors on the truck. It is applicable even when no independent ‘ground truth’ for the dynamic loads is available. The approach can be more widely used in the analysis of dynamic interactions involving suspended moving loads on deformable structures, e.g. for structural vibrations due to high-speed trains.

As part of a system for structural health monitoring, it is required to determine the spatial and temporal distributions of vertical loads arising from heavy trucks driven on flexible bridge structures. An instrumented truck is used to generate the input loads and estimate the load time histories. The truck can carry a range of sensors; however direct measurement of vertical tire loads between the tires and the structure is not considered realistic. The dynamic loads are to be estimated from the sensor outputs. These are affected by both truck and bridge dynamics and these must be accounted for within the load estimation process. Estimation may be susceptible to many factors including static mass distribution, vehicle longitudinal motion, variations in lateral position on the bridge, as well as any surface unevenness. The focus of this paper is on using high fidelity simulation models to develop appropriate methodologies for load estimation which optimize the use of sensors on the truck. The estimation methods are evaluated in the context of any loss of accuracy in the predicted bridge response and in particular the coherency between inputs and outputs. It is proposed that using only static tire load data, GPS satellite data, string-potentiometers and accelerometer measurements, a robust measurement system can be constructed. The goal is to use near real-time processing of truck sensor data so that dynamic truck loads are available; when combined with data from separate bridge-mounted sensors, the structural performance of the structure can be evaluated. © 2013 SAE International.

The dinuclear complex [Zn2(papy)2]·2CH3OH [H2papy = N- (2-hydroxybenzyl)-N-(2-picolyl)glycine] was synthesized and characterized. The crystal structure of the complex reveals that both ZnII ions are pentacoordinate with distorted pentagonal bipyramidal coordination arrangements. The phenoxyl groups of each ligand bridge the two metal atoms, whereas each carboxylate of the ligand is terminally bound to one ZnII ion. Potentiometric studies of the ZnII:H2papy system in a methanol/water mixture show the existence of a mononuclear species at lower pH; but at a pH above 5, a dimeric species starts to dominate and transforms further into a bis(μ-phenoxo) bridged dizinc complex by deprotonation of phenolic hydrogen. A kinetic study of the hydrolysis of bis(2,4-dinitrophenyl)phosphate at different pH, catalyzed by complex 1, indicates a maximum rate at pH 9, where the bis(μ-phenoxo)-bridged dizinc species corresponding to 1 dominates in solution. (Less)

Mistuning commonly refers to non-cyclically symmetric variations in such an otherwise cyclically-symmetric structure. Mistuning in a blisk due to variations in blade materials and geometry have been studied extensively and are known to have a significant impact on the forced response of blisks. However, mistuning can also arise due to variations at contact interfaces within a blisk with friction damping mechanisms such as under platform dampers or shrouds. Past literature analyzing the effect of this source of contact mistuning is limited, particularly by the use of lumped or single-node contacts at each sector to shorten analysis times. In this paper, we aim to better understand the specific effects of parameter variations across contact interfaces on an otherwise tuned blisk. A blisk with shroud to shroud contacts is considered. Accurate representation of microslip phenomena are incorporated in the analysis by modeling multiple localized node to node contact models at contact surfaces on each blisk sector. Contact stiffnesses which dictate the friction damping dynamics of the shrouds are chosen as the mistuning parameters. The harmonic balance method is used to solve for forced responses. We analyze cases with random patterns of contact stiffnesses in different microslip regimes in the proximity of different modal regions. Probabilistic analysis of nonlinear contact responses are carried out close to a linear region where comparatively high amplification factors are observed. Statistics are also developed for linear cases and compared with the nonlinear case to qualify the dependence of amplification factors of nonlinear forced responses on the level of microslip and on the variance of contact parameters.

Reduced order models (ROMs) of turbine bladed disks (blisks) are essential to quickly yet accurately characterize vibration characteristics and effectively design for high cycle fatigue. Modeling blisks with contacting shrouds at adjacent blades is especially challenging due to friction damping and localized nonlinearities at the contact interfaces which can lead to complex stick–slip behavior. While well-known techniques such as the harmonic balance method (HBM) and Craig–Bampton component mode synthesis (CB-CMS) have generally been employed to generate ROMs in the past, they do not reduce degrees-of-freedom (DoFs) at the interfaces themselves. In this paper, we propose a novel method to obtain a set of reduction basis functions for the contact interface DoFs as well as the remaining DoFs called “adaptive microslip projection” (AMP). The method is based on analyzing a set of linear systems with specifically chosen boundary conditions on the contact interface. Simulated responses of full order baseline models and the novel ROMs under various conditions are studied. Results obtained from the ROMs compare very favorably with the baseline model. This study addresses the case of a shrouded blisk in microslip close to stick. The AMP procedure may be possibly applied to other systems with Coulomb friction contacts, but its accuracy and effectiveness will need to be evaluated separately.

This paper presents a thermodynamical and aerodynamical analyses of the behaviour of a hypothetical lightweight combat aircraft operating on a single engine afterburning turbojet. An airframe was selected for the aircraft thus specifying the aerodynamical characteristics. Then an engine was developed to achieve the basic criteria for the fulfillment of certain predefined mission requirements such as taking off from a runway of specified length, supercruising at particular Mach number, performing high g combat turns, etc. The engine and the airframe were coupled to form a basic aircraft. The capabilities of this aircraft were reviewed thereafter at distinct stages of flight and its capability as an interceptor aircraft was analysed. After careful consideration of all the aspects of the theoretical aircraft, it was concluded that it fulfilled the numerous mandatory requirements demanded for an interceptor aircraft.

Reduced order models (ROMs) of turbine bladed disks (blisks) are essential to quickly yet accurately characterize vibration characteristics and effectively design for high cycle fatigue. Modeling blisks with contacting shrouds at adjacent blades is especially challenging due to friction damping and localized non-linearities at the contact interfaces which can lead to complex stick-slip behavior. While well-known techniques such as the harmonic balance method and Craig-Bampton component mode synthesis have generally been employed to generate ROMs in the past, they do not reduce degrees of freedom (DoFs) at the interfaces themselves. In this paper we propose a novel method to obtain a set of reduction basis functions for the contact interface DoFs as well as the remaining DoFs called adaptive microslip projection (AMP). The method is based on analyzing a set of linear systems with specifically chosen boundary conditions on the contact interface. Simulated responses of full order baseline models and the novel ROMs under various conditions are studied. Results obtained from the ROMs compare very favorably with the baseline model. The AMP procedure is also easily generalizable to other dynamic systems with Coulomb friction contacts.

Quantitative sensory testing (QST) can provide useful information about the underlying mechanisms involved in chronic pain. However, currently available devices typically employed suffer from operator-dependent effects, or are too cumbersome for routine clinical care. This paper presents the design and initial validation of a novel automated pressure-pain type QST platform, termed the multi-modal automated sensory testing (MAST) system. The MAST configuration presented consists of wireless, hand-held thumbnail pressure stimulators (with circular 10 mm2 rubber tips) and graphical touch screen interface devices to manage the QST process and obtain patient feedback. Validation testing of the custom-designed force sensor showed a 1 % error for low forces increasing to 2 % error for larger loads up to 100 N (full-scale). Validation of the controller using three ramp rates (64, 248, and 496 kPa/s) and six pressures (32, 62, 124, 273, 620, and 1116 kPa) showed an overall mean error of 1.7 % for applied stimuli. Clinical evaluation revealed decreased pressure pain thresholds in chronic pain patients (98.07 ± SE 16.34 kPa) compared to pain free, healthy control subjects (259.88 ± SE 33.54 kPa, p = 0.001). The MAST system is portable and produces accurate, repeatable stimulation profiles indicating potential for point-of-care applications.

Vehicle/structure interaction is extremely important in determining the structural performance of highway bridges. However, an accurate prediction of the generated vibrations and forces requires a high-fidelity nonlinear 3D model which is sufficiently representative of the actual vehicle and bridge structure. In spite of all the computational advancements, there are still many technical difficulties to obtain a converging solution from a coupled highly nonlinear and highly damped vehicle/structure models. This paper presents an iterative uncoupled approach to obtain an accurate estimation of the vehicle/structure interaction. The multi-axle vehicle is simulated using a nonlinear 3D multibody dynamics model. The bridge model also contains several nonlinear components to accurately model the bridge behavior. The vehicle/bridge interaction results are obtained through an iterative solution by exchanging the outputs of two uncoupled nonlinear models. A convergence criterion is selected to obtain a reliable solution after several of these iterations. Finally, a reduced-order model of the bridge is developed using a state-space model. The linear reduced-order model of the bridge is coupled with the nonlinear vehicle model to improve the solution time of the analysis. The results are in a very good agreement with the iterative uncoupled approach. © 2012 SPIE.