bluuebunny/crossref_metadata_2025 huggingface dataset:
Grounding Cognitive‐Level Processes in Behavior: The View From Dynamic Systems Theory
Authors: Samuelson Larissa K. , Jenkins Gavin W. , Spencer John P.
Published: March 2015

Marr's seminal work laid out a program of research by specifying key questions for cognitive science at different levels of analysis. Because dynamic systems theory (DST) focuses on time and interdependence of components, DST research programs come to very different conclusions regarding the nature of cognitive change. We review a specific DST approach to cognitive‐level processes: dynamic field theory (DFT). We review research applying DFT to several cognitive‐level processes: object permanence, naming hierarchical categories, and inferring intent, that demonstrate the difference in understanding of behavior and cognition that results from a DST perspective. These point to a central challenge for cognitive science research as defined by Marr—emergence. We argue that appreciating emergence raises questions about the utility of computational‐level analyses and opens the door to insights concerning the origin of novel forms of behavior and thought (e.g., a new chess strategy). We contend this is one of the most fundamental questions about cognition and behavior.
Chromatin dynamics of plant telomeres and ribosomal genes
Authors: Dvořáčková Martina , Fojtová Miloslava , Fajkus Jiří
Published: March 2015

Telomeres and genes encoding 45S ribosomal RNA (rDNA) are frequently located adjacent to each other on eukaryotic chromosomes. Although their primary roles are different, they show striking similarities with respect to their features and additional functions. Both genome domains have remarkably dynamic chromatin structures. Both are hypersensitive to dysfunctional histone chaperones, responding at the genomic and epigenomic levels. Both generate non‐coding transcripts that, in addition to their epigenetic roles, may induce gross chromosomal rearrangements. Both give rise to chromosomal fragile sites, as their replication is intrinsically problematic. However, at the same time, both are essential for maintenance of genomic stability and integrity. Here we discuss the structural and functional inter‐connectivity of telomeres and rDNA, with a focus on recent results obtained in plants.
Targeting of the Hydrophobic Metabolome by Pathogens
Authors: Helms J. Bernd , Kaloyanova Dora V. , Strating Jeroen R. P. , van Hellemond Jaap J. , van der Schaar Hilde M. , Tielens Aloysius G. M. , van Kuppeveld Frank J. M. , Brouwers Jos F.
Published: March 2015

The hydrophobic molecules of the metabolome – also named the lipidome – constitute a major part of the entire metabolome. Novel technologies show the existence of a staggering number of individual lipid species, the biological functions of which are, with the exception of only a few lipid species, unknown. Much can be learned from pathogens that have evolved to take advantage of the complexity of the lipidome to escape the immune system of the host organism and to allow their survival and replication. Different types of pathogens target different lipids as shown in interaction maps, allowing visualization of differences between different types of pathogens. Bacterial and viral pathogens target predominantly structural and signaling lipids to alter the cellular phenotype of the host cell. Fungal and parasitic pathogens have complex lipidomes themselves and target predominantly the release of polyunsaturated fatty acids from the host cell lipidome, resulting in the generation of eicosanoids by either the host cell or the pathogen. Thus, whereas viruses and bacteria induce predominantly alterations in lipid metabolites at the host cell level, eukaryotic pathogens focus on interference with lipid metabolites affecting systemic inflammatory reactions that are part of the immune system. A better understanding of the interplay between host–pathogen interactions will not only help elucidate the fundamental role of lipid species in cellular physiology, but will also aid in the generation of novel therapeutic drugs.
MULTIDETECTOR‐ROW COMPUTED TOMOGRAPHY PATTERNS OF BRONCHOESPHAGEAL ARTERY HYPERTROPHY AND SYSTEMIC‐TO‐PULMONARY FISTULA IN DOGS
Authors: Ledda Gianluca , Caldin Marco , Mezzalira Giorgia , Bertolini Giovanna
Published: March 2015

Anomalies involving arterial branches in the lungs are one of the causes of hemoptysis in humans and dogs. Congenital and acquired patterns of bronchoesophageal artery hypertrophy have been reported in humans based on CT characteristics. The purpose of this retrospective study was to describe clinical, echocardiographic, and multidetector computed tomography features of bronchoesophageal artery hypertrophy and systemic‐to‐pulmonary arterial communications in a sample of 14 dogs. Two main vascular patterns were identified in dogs that resembled congenital and acquired conditions reported in humans. Pattern 1 appeared as an aberrant origin of the right bronchoesophageal artery, normal origin of the left one, and enlargement of both the bronchial and esophageal branches that formed a dense network terminating in a pulmonary artery through an orifice. Pattern 2 appeared as a normal origin of both right and left bronchoesophageal arteries, with an enlarged and tortuous course along the bronchi to the periphery of the lung, where they communicated with subsegmental pulmonary arteries. Dogs having Pattern 1 also had paraesophageal and esophageal varices, with the latter being confirmed by videoendoscopy examination. Authors conclude that dogs with Pattern 1 should be differentiated from dogs with other congenital vascular systemic‐to‐pulmonary connections. Dogs having Pattern 2 should be evaluated for underlying pleural or pulmonary diseases. Bronchoesophageal artery hypertrophy can be accompanied by esophageal venous engorgement and should be included in the differential diagnosis for esophageal and paraesophageal varices in dogs.
A Three-Dimensional Ankle Kinetostatic Model to Simulate Loaded and Unloaded Joint Motion
Authors: Forlani Margherita , Sancisi Nicola , Parenti-Castelli Vincenzo
Published: March 2015

A kinetostatic model able to replicate both the natural unloaded motion of the tibiotalar (or ankle) joint and the joint behavior under external loads is presented. The model is developed as the second step of a sequential procedure, which allows the definition of a kinetostatic model as a generalization of a kinematic model of the joint defined at the first step. Specifically, this kinematic model taken as the starting point of the definition procedure is a parallel spatial mechanism which replicates the ankle unloaded motion. It features two rigid bodies (representing the tibia–fibula and the talus–calcaneus complexes) interconnected by five rigid binary links, that mimic three articular contacts and two nearly isometric fibers (IFs) of the tibiocalcaneal ligament (TiCaL) and calcaneofibular ligament (CaFiL). In the kinetostatic model, the five links are considered as compliant; moreover, further elastic structures are added to represent all the main ankle passive structures of the joint. Thanks to this definition procedure, the kinetostatic model still replicates the ankle unloaded motion with the same accuracy as the kinematic model. In addition, the model can replicate the behavior of the joint when external loads are applied. Finally, the structures that guide these motions are consistent with the anatomical evidence. The parameters of the model are identified for two specimens from both subject-specific and published data. Loads are then applied to the model in order to simulate two common clinical tests. The model-predicted ankle motion shows good agreement with results from the literature.
Effects of Age and Diabetes on Scleral Stiffness
Authors: Coudrillier Baptiste , Pijanka Jacek , Jefferys Joan , Sorensen Thomas , Quigley Harry A. , Boote Craig , Nguyen Thao D.
Published: March 2015

The effects of diabetes on the collagen structure and material properties of the sclera are unknown but may be important to elucidate whether diabetes is a risk factor for major ocular diseases such as glaucoma. This study provides a quantitative assessment of the changes in scleral stiffness and collagen fiber alignment associated with diabetes. Posterior scleral shells from five diabetic donors and seven non-diabetic donors were pressurized to 30 mm Hg. Three-dimensional surface displacements were calculated during inflation testing using digital image correlation (DIC). After testing, each specimen was subjected to wide-angle X-ray scattering (WAXS) measurements of its collagen organization. Specimen-specific finite element models of the posterior scleras were generated from the experimentally measured geometry. An inverse finite element analysis was developed to determine the material properties of the specimens, i.e., matrix and fiber stiffness, by matching DIC-measured and finite element predicted displacement fields. Effects of age and diabetes on the degree of fiber alignment, matrix and collagen fiber stiffness, and mechanical anisotropy were estimated using mixed effects models accounting for spatial autocorrelation. Older age was associated with a lower degree of fiber alignment and larger matrix stiffness for both diabetic and non-diabetic scleras. However, the age-related increase in matrix stiffness was 87% larger in diabetic specimens compared to non-diabetic controls and diabetic scleras had a significantly larger matrix stiffness (p = 0.01). Older age was associated with a nearly significant increase in collagen fiber stiffness for diabetic specimens only (p = 0.06), as well as a decrease in mechanical anisotropy for non-diabetic scleras only (p = 0.04). The interaction between age and diabetes was not significant for all outcomes. This study suggests that the age-related increase in scleral stiffness is accelerated in eyes with diabetes, which may have important implications in glaucoma.
Friction Induced Vibration in Windscreen Wiper Contacts
Authors: Reddyhoff Tom , Dobre Oana , Le Rouzic Julian , Gotzen Nicolaas-Alexander , Parton Hilde , Dini Daniele
Published: March 2015

This research is aimed at understanding the mechanisms that give rise to friction induced noise in automotive windscreen wipers, with a focus on frequencies between 500 and 3500 Hz. To study this phenomenon, experimental friction, sound, and high-speed video measurements are combined with finite element modeling of a rubber wiper/glass contact. In agreement with previous research, simultaneous sound and friction measurements showed that wiper noise in this frequency range results from the negative damping effect caused by the dependence of friction on speed in the mixed lubrication regime. Furthermore, during sliding, the friction induced noise recorded by the microphone occurred in one of two frequency ranges (close to 1000 Hz and between 2000 and 2500 Hz). These coincided closely with the eigen-frequencies of first two bending modes, predicted by finite element modeling. Experimental observations also showed the wiper to be oscillating backward and forward without any torsional motion and that the thickness of the glass had no effect on the emitted noise. These observations highlight how friction induced noise—although caused by conditions within contact—has characteristics that are determined by the structure of the excited component. A number of additional findings are made. Most importantly, both experiment and finite element modeling showed that the presence of water in contact with the wiper modulates the frequency and amplitude of the emitted noise by effectively adding mass to the vibrating system. While this is occurring, Faraday-like standing waves are observed in the water. In addition to this, friction induced vibration is shown only to occur for glass surfaces with intermediate surface energies, which is possibly due to high contact angles preventing water reaching the contact. Based on the understanding gained, a number of suggestions are made regarding means of reducing windscreen wiper noise.
Detection of Bearing Fault Detection From Heavily Contaminated Signals: A Higher-Order Analytic Energy Operator Method
Authors: Faghidi H. , Liang M.
Published: March 2015

This paper reports a higher-order analytic energy operator (HO-AEO) approach to monitoring bearing health conditions from vibrations signals that are polluted by strong noise and multiple interferences. The proposed analytic energy operator (AEO) is formed using the raw signal, its Hilbert transform, and their derivatives. In analogy to the conventional energy operator (EO), it represents an alternative energy transformation. However, unlike the conventional EO, it exploits the information from both the real and imaginary parts of the analytic signal. It can also extract both the amplitude and frequency modulations and is thus well suited for detecting impulsive fault signature. The joint use of multiple higher-order AEOs can further offset noise effect. The built-in amplitude demodulation (AD) capability of the proposed HO-AEO eliminates the enveloping step required by most high-frequency resonance (HFR) methods. The method is simple and easy to implement. Our simulation and experimental results have demonstrated that the proposed method can effectively extract bearing fault signature in the presence of heavy noise and multiple vibration interferences. It has also been shown mathematically that the HO-AEO processed signal yields higher signal-to-interference ratio (SIR) than the conventional EO does. The simulation and experimental comparisons also indicate that the proposed method has much better noise and interference handling capabilities than the conventional EO.
Periodic Response of a Duffing Oscillator Under Combined Harmonic and Random Excitations
Authors: Zhu Hai-Tao , Guo Siu-Siu
Published: March 2015

This paper presents a solution procedure to investigate the periodic response of a Duffing oscillator under combined harmonic and random excitations. The solution procedure consists of an implicit harmonic balance method and a Gaussian closure method. The implicit harmonic balance method, previously developed for the case of harmonic excitation, is extended to the present case of combined harmonic and random excitations with the help of the Gaussian closure method. The amplitudes of the periodic response and the steady variances can be automatically found by the proposed solution procedure. First, the response process is separated into the mean part and the random process part. Then the Gaussian closure method is adopted to reformulate the original equation into two coupled differential equations. One is a deterministic equation about the mean part and the other is a stochastic equivalent linear equation. In terms of these two coupled equations, the implicit harmonic balance method is used to obtain a set of nonlinear algebraic equations relating to amplitudes, frequency, and variance. The resulting equations are not explicitly determined and they can be implicitly solved by nonlinear equation routines available in most mathematical libraries. Three illustrative examples are further investigated to show the effectiveness of the proposed solution procedure. Furthermore, the proposed solution procedure is particularly convenient for programming and it can be extended to obtain the periodic solutions of the response of multi degrees-of-freedom systems.
On the Thermomechanical Response of HTPB-Based Composite Beams Under Near-Resonant Excitation
Authors: Woods Daniel C. , Miller Jacob K. , Rhoads Jeffrey F.
Published: March 2015

Currently, there is a pressing need to detect and identify explosive materials in both military and civilian settings. While these energetic materials vary widely in both form and composition, many traditional explosives consist of a polymeric binder material with embedded energetic crystals. Interestingly, many polymers exhibit considerable self-heating when subjected to harmonic loading, and the vapor pressures of many explosives exhibit a strong dependence on temperature. In light of these facts, thermomechanics represent an intriguing pathway for the stand-off detection of explosives, as the thermal signatures attributable to motion-induced heating may allow target energetic materials to be distinguished from their more innocuous counterparts. In the present work, the thermomechanical response of a sample from this class of materials is studied in depth. Despite the nature of the material as a polymer-based particulate composite, classical Euler–Bernoulli beam theory, along with the complex modulus representation for linear viscoelastic materials, was observed to yield predictions of the thermal and mechanical responses in agreement with experimental investigations. The results of the experiments conducted using a hydroxyl-terminated polybutadiene (HTPB) beam with embedded ammonium chloride (NH4Cl) crystals are presented. Multiple excitation levels are employed and the results are subsequently compared to the work's analytical findings.
Effect of Surface Properties Modification on Slurry Erosion–Corrosion Resistance of AISI 5117 Steel
Authors: Saleh B. , Abouel-Kasem A. , Ahmed S. M.
Published: March 2015

The erosion–corrosion (E–C) wear behaviors of electroless nickel phosphorus (Ni-P) coating, carburizing and untreated low alloy steel AISI 5117 in water–sand slurry and saline–sand slurry were investigated using whirling-arm tester. The E–C wear mass loss was measured to evaluate the effect of mediums and surface modifications. The microstructure of carburizing and Ni-P coating was analyzed using an optical and scanning electron microscope (SEM) and X-ray diffraction (XRD) technique. Results showed that Ni-P coating and carburizing are effective in increasing wear resistance of low alloy steel. However, the Ni-P coating is more effective in increasing the E–C resistance. Also, the results showed that Ni-P coating, carburizing and untreated carbon steel behaved as ductile materials under erosion and E–C tests, and the maximum mass loss occurred at an impact angle of 45 deg. The synergism ratio was the lowest for the Ni-P coating, indicating that Ni-P coating improved an anti-E–C wear resistance.
Experimental and Numerical Analyses of Dented Stiffened Panels
Authors: Amante Diogo do Amaral M. , Chujutalli John Alex , Estefen Segen F.
Published: March 2015

Numerical–experimental correlation study for small scale damaged stiffened panels was performed. Six small scale models were fabricated. Two of them were employed for the correlation of intact panels and the remaining four for the correlation of dented panels. Ultimate strength analyses were carried out in order to adjust the numerical model for further use in parametric studies. The damage was imposed by a local indentation of the panels. Measurements of geometric imperfection distributions and damage shapes have been performed before and after the damage using a laser tracker equipment. The numerical models were represented by shell elements assuming finite membrane strains and large rotations, considering both geometric and material nonlinearities. Results obtained showed very good agreement between experimental and numerical analyses for both intact and dented panels. Additionally, numerical simulations of damaged stiffened panels were performed. The aim of the parametric study was to evaluate the behavior up to and beyond buckling, to observe the strength loss due to the presence of the damage on the panel. The explicit nonlinear finite element code from abaqus program was employed to simulate the dent damage. Therefore, distortions and the residual stresses due to the damage were both considered in subsequent numerical compression analyses.
Thermorheological Characterization of Elastoviscoplastic Carbopol Ultrez 20 Gel
Authors: Hassan M. A. , Pathak Manabendra , Khan Mohd. Kaleem
Published: March 2015

The temperature and concentration play an important role on rheological parameters of the gel. In this work, an experimental investigation of thermorheological properties of aqueous gel Carbopol Ultrez 20 for various concentrations and temperatures has been presented. Both controlled stress ramps and controlled stress oscillatory sweeps were performed for obtaining the rheological data to find out the effect of temperature and concentration. The hysteresis or thixotropic seemed to have negligible effect. Yield stress, consistency factor, and power law index were found to vary with temperature as well as concentration. With gel concentration, the elastic effect was found to increase whereas viscous dissipation effect was found to decrease. Further, the change in elastic properties was insignificant with temperature in higher frequency range of oscillatory stress sweeps.
A Reparametrization of the Rotation Matrix in Rigid-Body Dynamics
Authors: Zhu Xiaoqing , Angeles Jorge
Published: March 2015

The parametrization of a rigid-body rotation is a classical subject in rigid-body dynamics. Euler angles, the rotation matrix and quaternions are the most common representations. However, Euler angles are known to be prone to singularities, besides not being frame-invariant. The full 3 × 3 rotation matrix conveys all the motion information, but poses the problem of an excessive number of parameters, nine, to represent a transformation that entails only three independent parameters. Quaternions are singularity-free, and thus, ideal to study rigid-body kinematics. However, quaternions, comprising four components, are subject to one scalar constraint, which has to be included in the mathematical model of rigid-body dynamics. The outcome is that the use of quaternions imposes one algebraic constraint, even in the case of mechanically unconstrained systems. An alternative parametrization is proposed here, that (a) comprises only three independent parameters; (b) is fairly robust to representation singularities; and (c) satisfies the quaternion scalar constraint intrinsically. To illustrate the concept, a simple, yet nontrivial case study is included. This is a mechanical system composed of a rigid, toroidal wheel rolling without slipping or skidding on a horizontal surface. The simulation algorithm based on the proposed parametrization and fundamentally on quaternions, together with the invariant relations between the quaternion rate of change and the angular velocity, is capable of reproducing the falling of the wheel under deterministic initial conditions and a random disturbance acting on the tilting axis. Finally, a comparative study is included, on the numerical conditioning of the parametrization proposed here and that based on Euler angles. Ours shows as broader well-conditional region than Euler angles offer. Moreover, the two parametrizations exhibit an outstanding complementarity: where the conditioning of one degenerates, the other comes to rescue.
Analyses on the In-Plane Impact Resistance of Auxetic Double Arrowhead Honeycombs
Authors: Qiao Jinxiu , Chen Chang Qing
Published: March 2015

Double arrowhead honeycombs (DAHs) are a type of auxetic materials, i.e., showing negative Poisson's ratio (NPR), and are promising for energy absorption applications. Their in-plane impact responses are theoretically and numerically explored. Theoretical models for the collapse stress under quasi-static, low-velocity, and high-velocity impacts are developed, based upon the corresponding microstructural deformation modes. Obtained results show that the collapse stress under quasi-static and low velocity impacts depends upon the two re-entrant angles responsible for NPR, while it is insensitive to them under high-velocity impact. The developed theoretical models are employed to analyze the energy absorption capacity of DAHs, showing the absorbed energy under high-velocity impact approximately proportional to the second power of velocity. Extension of the high-velocity impact model to functionally graded (FG) DAHs is also discussed. Good agreement between the theoretical and finite element (FE) predictions on the impact responses of DAHs is obtained.
A Semantic Information Services Framework for Sustainable WEEE Management Toward Cloud-Based Remanufacturing
Authors: Xia Kai , Gao Liang , Wang Lihui , Li Weidong , Chao Kuo-Ming
Published: March 2015

Sustainable management of waste electrical and electronic equipment (WEEE) has attracted escalating concerns of researchers and industries. Closer information linking among the participants in the products's lifecycle should take place. How to interoperate among the distributed and heterogeneous information systems of various participants is a challenge faced. Targeting the cloud-based remanufacturing, this article aims to develop a semantic information services framework for sustainable WEEE management. In the proposed framework, an ontology based approach is developed to integrate and represent the lifecycle information from multiple local data sources within an information services provider. Meanwhile, a semantic information services management platform is introduced for the advertisement, matchmaking and retrieval of semantic information services. Some relevant techniques used to build the framework are introduced extensively. A demonstration case study on waste LCD TV is used to illustrate the effectiveness and significance of the proposed framework.
Carbon nanotubes field emission enhancement using a laser post treatment
Authors: Ulisse Giacomo , Brunetti Francesca , Di Carlo Aldo , Orlanducci Silvia , Tamburri Emanuela , Guglielmotti Valeria , Marrani Marco , Terranova Maria Letizia
Published: March 2015

This paper reports the fabrication of a cold cathode based on carbon nanotubes (CNTs) using a combined chemical vapor deposition technique and a laser processing treatment. The CNTs are exposed to a focused 514 nm continuous-wave laser at varying power, and the changes of the CNTs characteristics after each laser treatment are investigated by Raman spectroscopy and scanning electron microscopy. It is seen that a laser treatment at 70 mW produces an improved emitter, characterized by an increase of the field emitted current up to 350 times, which obtains a maximum current density of 0.13 A/cm2. The CNT deposit exhibits good time stability and a good resistance under high applied electric fields up to 33 V/μm. The results obtained in terms of current density make the laser treatment an excellent process for increasing the performance of cathodes to be used in electron guns for vacuum tubes where high current densities are required.
Precursors for carbon doping of GaN in chemical vapor deposition
Authors: Li Xun , Danielsson Örjan , Pedersen Henrik , Janzén Erik , Forsberg Urban
Published: March 2015

Methane (CH4), ethylene (C2H4), acetylene (C2H2), propane (C3H8), iso-butane (i-C4H10), and trimethylamine [N(CH3)3] have been investigated as precursors for intentional carbon doping of (0001) GaN in chemical vapor deposition. The carbon precursors were studied by comparing the efficiency of carbon incorporation in GaN together with their influence on morphology and structural quality of carbon doped GaN. The unsaturated hydrocarbons C2H4 and C2H2 were found to be more suitable for carbon doping than the saturated ones, with higher carbon incorporation efficiency and a reduced effect on the quality of the GaN epitaxial layers. The results indicate that the C2H2 molecule as a direct precursor, or formed by the gas phase chemistry, is a key species for carbon doping without degrading the GaN quality; however, the CH3 species should be avoided in the carbon doping chemistry.
Infected florid osseous dysplasia: clinical and imaging follow-up
Authors: Mufeed Abdulla , Mangalath Ummar , George Antony , Hafiz Abdul
Published: March 2015

Florid osseous dysplasia (FOD) is a rare fibro-osseous lesion of the jaw usually identified incidentally on radiograph. It rarely presents with clinical symptoms. A case of FOD presenting with features similar to osteomyelitis is discussed here. The diagnosis is based on radiographic findings; biopsy or surgical intervention should be avoided as it may predispose to infection.
A solid-state17O NMR study of platinum-carboxylate complexes: carboplatin and oxaliplatin
Authors: Kong Xianqi , Terskikh Victor , Toubaei Abouzar , Wu Gang
Published: March 2015

We report synthesis and solid-state NMR characterization of two17O-labeled platinum anticancer drugs: cis-diammine(1,1-cyclobutane-[17O4]dicarboxylato)platinum(II) (carboplatin) and ([17O4]oxalato)[(1R, 2R)-(−)-1,2-cyclohexanediamine)]platinum(II) (oxaliplatin). Both17O chemical shift (CS) and quadrupolar coupling (QC) tensors were measured for the carboxylate groups in these two compounds. With the aid of plane wave DFT computations, the17O CS and QC tensor orientations were determined in the molecular frame of reference. Significant changes in the17O CS and QC tensors were observed for the carboxylate oxygen atom upon its coordination to Pt(II). In particular, the17O isotropic chemical shifts for the oxygen atoms directly bonded to Pt(II) are found to be smaller (more shielded) by 200 ppm than those for the non-Pt-coordinated oxygen atoms within the same carboxylate group. Examination of the17O CS tensor components reveals that such a large17O coordination shift is primarily due to the shielding increase along the direction that is within the O=C–O–Pt plane and perpendicular to the O–Pt bond. This result is interpreted as due to the σ donation from the oxygen nonbonding orbital (electron lone pair) to the Pt(II) empty dyzorbital, which results in large energy gaps between σ(Pt–O) and unoccupied molecular orbitals, thus reducing the paramagnetic shielding contribution along the direction perpendicular to the O–Pt bond. We found that the17O QC tensor of the carboxylate oxygen is also sensitive to Pt(II) coordination, and that17O CS and QC tensors provide complementary information about the O–Pt bonding.
Localization of magnetic and electronic excitations in nanotubes with line defects
Authors: Komorowski P. G. , Cottam M. G.
Published: March 2015

A matrix Green's function formalism is employed to study the excitations in long nanotubes where the dynamics are governed by nearest-neighbor interactions between atoms. Examples of the excitations, which can be characterized in terms of the tube circumference and a one-dimensional wave number along the length, include ferromagnetic spin waves in a Heisenberg exchange model and electronic modes in a tight-binding model with hopping. It is assumed that the system is a single-walled nanotube of negligible thickness and that the atoms are arranged on a simple square lattice. Defects in the form of substitutional impurity atoms are introduced to study localized modes as well as the propagating modes of the pure (host) material. The impurities have the form of one or more line defects parallel to the nanotube axis. The derived Green's functions provide a description of the frequencies of the discrete modes of the system and their spectral intensities. Numerical examples are presented for different mode types (magnetic and electronic), nanotube diameters and arrangements of impurity lines.
INTELLECTUAL CAPITAL AND INNOVATIONS: IS ORGANISATIONAL CAPITAL A MISSING LINK IN THE SERVICE SECTOR?
Authors: ELSETOUHI AHMED , ELBELTAGI IBRAHIM , HADDOUD MOHAMED YACINE
Published: March 2015

This paper analyses the direct and indirect effects of social capital (SC), human capital (HC) and customer capital (CC) on the different types of innovations via organisational capital (OC) in the service sector. The study gathered data from 198 managers in the Egyptian banks (54% response rate). The research findings indicate that product, process and organisational innovations are positively associated with OC, SC and HC have direct and indirect positive effects on both product and organisational innovation via OC. It seems that SC and HC do not have a direct influence on process innovation because OC fully mediates the relationship between SC, HC and process innovation. This study explored the direct and indirect positive effects of CC on three types of innovation through OC. Additionally, all organisational, process and product innovations are found to be inter-correlated. The most significant influence of intellectual capital (IC) is on product innovation, followed by organisational innovation, whereas the least significant influence is on process innovation.
Piezoelectric materials selection for sensor applications using finite element and multiple attribute decision-making approaches
Authors: Kumar Anuruddh , Sharma Anshul , Kumar Rajeev , Vaish Rahul , Chauhan Vishal S , Bowen C. R.
Published: March 2015

This paper examines the selection and performance evaluation of a variety of piezoelectric materials for cantilever-based sensor applications. The finite element analysis method is implemented to evaluate the relative importance of materials properties such as Young's Modulus (E), piezoelectric stress constants (e31), dielectric constant (ε) and Poisson's ratio (υ) for cantilever-based sensor applications. An analytic hierarchy process (AHP) is used to assign weights to the properties that are studied for the sensor structure under study. A technique for order preference by similarity to ideal solution (TOPSIS) is used to rank the performance of the piezoelectric materials in the context of sensor voltage outputs. The ranking achieved by the TOPSIS analysis is in good agreement with the results obtained from finite element method simulation. The numerical simulations show that K 0.5 Na 0.5 NbO 3– LiSbO 3 (KNN–LS) materials family is important for sensor application. Young's modulus (E) is most influencing material's property followed by piezoelectric constant (e31), dielectric constant (ε) and Poisson's ratio (υ) for cantilever-based piezoelectric sensor applications.
Multilevel Phase Analysis
Authors: Zhang Weihua , Li Jiaxin , Li Yi , Chen Haibo
Published: March 2015

Phase analysis, which classifies the set of execution intervals with similar execution behavior and resource requirements, has been widely used in a variety of systems, including dynamic cache reconfiguration, prefetching, race detection, and sampling simulation. Although phase granularity has been a major factor in the accuracy of phase analysis, it has not been well investigated, and most systems usually adopt a fine-grained scheme. However, such a scheme can only take account of recent local phase information and could be frequently interfered by temporary noise due to instant phase changes, which might notably limit the accuracy.

In this article, we make the first investigation on the potential of multilevel phase analysis (MLPA), where different granularity phase analyses are combined together to improve the overall accuracy. The key observation is that the coarse-grained intervals belonging to the same phase usually consist of
stably distributed
fine-grained phases. Moreover, the phase of a coarse-grained interval can be accurately identified based on the fine-grained intervals at the beginning of its execution. Based on the observation, we design and implement an MLPA scheme. In such a scheme, a coarse-grained phase is first identified based on the fine-grained intervals at the beginning of its execution. The following fine-grained phases in it are then predicted based on the sequence of fine-grained phases in the coarse-grained phase. Experimental results show that such a scheme can notably improve the prediction accuracy. Using a Markov fine-grained phase predictor as the baseline, MLPA can improve prediction accuracy by 20%, 39%, and 29% for next phase, phase change, and phase length prediction for SPEC2000, respectively, yet incur only about 2% time overhead and 40% space overhead (about 360 bytes in total). To demonstrate the effectiveness of MLPA, we apply it to a dynamic cache reconfiguration system that dynamically adjusts the cache size to reduce the power consumption and access time of the data cache. Experimental results show that MLPA can further reduce the average cache size by 15% compared to the fine-grained scheme.

Moreover, for MLPA, we also observe that coarse-grained phases can better capture the overall program characteristics with fewer of phases and the last representative phase could be classified in a very early program position, leading to fewer execution internals being functionally simulated. Based on this observation, we also design a multilevel sampling simulation technique that combines both fine- and coarse-grained phase analysis for sampling simulation. Such a scheme uses fine-grained simulation points to represent only the selected coarse-grained simulation points instead of the entire program execution; thus, it could further reduce both the functional and detailed simulation time. Experimental results show that MLPA for sampling simulation can achieve a speedup in simulation time of about 8.3X with similar accuracy compared to 10M SimPoint.
Identification of Dynamic Circuit Specialization Opportunities in RTL Code
Authors: Davidson Tom , Vansteenkiste Elias , Heyse Karel , Bruneel Karel , Stroobandt Dirk
Published: March 2015

Dynamic Circuit Specialization (DCS) optimizes a Field-Programmable Gate Array (FPGA) design by assuming a set of its input signals are constant for a reasonable amount of time, leading to a smaller and faster FPGA circuit. When the signals actually change, a new circuit is loaded into the FPGA through runtime reconfiguration. The signals the design is specialized for are called parameters. For certain designs, parameters can be selected so the DCS implementation is both smaller and faster than the original implementation. However, DCS also introduces an overhead that is difficult for the designer to take into account, making it hard to determine whether a design is improved by DCS or not. This article presents extensive results on a profiling methodology that analyses Register-Transfer Level (RTL) implementations of applications to check if DCS would be beneficial. It proposes to use the functional density as a measure for the area efficiency of an implementation, as this measure contains both the overhead and the gains of a DCS implementation. The first step of the methodology is to analyse the dynamic behaviour of signals in the design, to find good parameter candidates. The overhead of DCS is highly dependent on this dynamic behaviour. A second stage calculates the functional density for each candidate and compares it to the functional density of the original design. The profiling methodology resulted in three implementations of a profiling tool, the DCS-RTL profiler. The execution time, accuracy, and the quality of each implementation is assessed based on data from 10 RTL designs. All designs, except for the two 16-bit adaptable Finite Impulse Response (FIR) filters, are analysed in 1 hour or less.
Temperature-Aware Data Allocation for Embedded Systems with Cache and Scratchpad Memory
Authors: Jia Zhiping , Li Yang , Wang Yi , Wang Meng , Shao Zili
Published: March 2015

The hybrid memory architecture that contains both on-chip cache and scratchpad memory (SPM) has been widely used in embedded systems. In this article, we explore this hybrid memory architecture by jointly optimizing time performance and temperature for embedded systems with loops. Our basic idea is to adaptively adjust the workload distribution between cache and SPM based on the current temperature. For a problem in which the workload can be estimated a priori, we present a nonlinear programming formulation to optimally minimize the total execution time of a loop under the constraints of SPM size and temperature. To solve a problem in which the workload is not known a priori, we propose a temperature-aware adaptive loop scheduling algorithm called
TALS
to dynamically allocate data to cache and SPM at runtime. The experimental results show that our algorithms can effectively achieve both performance and temperature optimization for embedded systems with cache and SPM.
Exploring the Benefits of Context in 3D Gesture Recognition for Game-Based Virtual Environments
Authors: Taranta II Eugene M. , Simons Thaddeus K. , Sukthankar Rahul , Laviola Jr. Joseph J.
Published: March 2015

We present a systematic exploration of how to utilize video game context (e.g., player and environmental state) to modify and augment existing 3D gesture recognizers to improve accuracy for large gesture sets. Specifically, our work develops and evaluates three strategies for incorporating context into 3D gesture recognizers. These strategies include modifying the well-known Rubine linear classifier to handle unsegmented input streams and per-frame retraining using contextual information (CA-Linear); a GPU implementation of dynamic time warping (DTW) that reduces the overhead of traditional DTW by utilizing context to evaluate only relevant time sequences inside of a multithreaded kernel (CA-DTW); and a multiclass SVM with per-class probability estimation that is combined with a contextually based prior probability distribution (CA-SVM).

We evaluate each strategy using a Kinect-based third-person perspective VE game prototype that combines parkour-style navigation with hand-to-hand combat. Using a simple gesture collection application to collect a set of 57 gestures and the game prototype that implements 37 of these gestures, we conduct three experiments. In the first experiment, we evaluate the effectiveness of several established classifiers on our gesture set and demonstrate state-of-the-art results using our proposed method. In our second experiment, we generate 500 random scenarios having between 5 and 19 of the 57 gestures in context. We show that the contextually aware classifiers CA-Linear, CA-DTW, and CA-SVM significantly outperform their non--contextually aware counterparts by 37.74%, 36.04%, and 20.81%, respectively. On the basis of the results of the second experiment, we derive upper-bound expectations for in-game performance for the three CA classifiers: 96.61%, 86.79%, and 96.86%, respectively. Finally, our third experiment is an in-game evaluation of the three CA classifiers with and without context. Our results show that through the use of context, we are able to achieve an average in-game recognition accuracy of 89.67% with CA-Linear compared to 65.10% without context, 79.04% for CA-DTW compared to 58.1% without context, and 90.85% with CA-SVM compared to 75.2% without context.
Effective Runtime Resource Management Using Linux Control Groups with the BarbequeRTRM Framework
Authors: Bellasi Patrick , Massari Giuseppe , Fornaciari William
Published: March 2015

The extremely high technology process reached by silicon manufacturing (smaller than 32nm) has led to production of computational platforms and SoC, featuring a considerable amount of resources. Whereas from one side such multi- and many-core platforms show growing performance capabilities, from the other side they are more and more affected by power, thermal, and reliability issues. Moreover, the increased computational capabilities allows congested usage scenarios with workloads subject to mixed and time-varying requirements. Effective usage of the resources should take into account both the
application requirements
and
resources availability
, with an arbiter, namely a resource manager in charge to solve the resource contention among demanding applications.

Current operating systems (OS) have only a limited knowledge about application-specific behaviors and their time-varying requirements. Dedicated system interfaces to collect such inputs and forward them to the OS (e.g., its scheduler) are thus an interesting research area that aims at integrating the OS with an ad hoc resource manager. Such a component can exploit efficient low-level OS interfaces and mechanisms to extend its capabilities of controlling tasks and system resources. Because of the specific tasks and timings of a resource manager, this component can be easily and effectively developed as a user-space extension lying in between the OS and the controlled application.

This article, which focuses on multicore Linux systems, shows a portable solution to enforce runtime resource management decisions based on the standard control groups framework. A
burst
and a
mixed workload
analysis, performed on a multicore-based NUMA platform, have reported some promising results both in terms of performance and power saving.
A Tradeoff Analysis of FPGAs, GPUs, and Multicores for Sliding-Window Applications
Authors: Cooke Patrick , Fowers Jeremy , Brown Greg , Stitt Greg
Published: March 2015

The increasing usage of hardware accelerators such as Field-Programmable Gate Arrays (FPGAs) and Graphics Processing Units (GPUs) has significantly increased application design complexity. Such complexity results from a larger design space created by numerous combinations of accelerators, algorithms, and hw/sw partitions. Exploration of this increased design space is critical due to widely varying performance and energy consumption for each accelerator when used for different application domains and different use cases. To address this problem, numerous studies have evaluated specific applications across different architectures. In this article, we analyze an important domain of applications, referred to as
sliding-window applications
, implemented on FPGAs, GPUs, and multicore CPUs. For each device, we present optimization strategies and analyze use cases where each device is most effective. The results show that, for large input sizes, FPGAs can achieve speedups of up to 5.6× and 58× compared to GPUs and multicore CPUs, respectively, while also using up to an order of magnitude less energy. For small input sizes and applications with frequency-domain algorithms, GPUs generally provide the best performance and energy.
Reliable Task Allocation with Load Balancing in Multiplex Networks
Authors: Jiang Yichuan , Zhou Yifeng , Li Yunpeng
Published: March 2015

In multiplex networks, agents are connected by multiple types of links; a multiplex network can be split into more than one network layer that is composed of the same type of links and involved agents. Each network link type has a bias for communicating different types of resources; thus, the task’s access to the required resources in multiplex networks is strongly related to the network link types. However, traditional task allocation and load balancing methods only considered the situations of agents themselves and did not address the effects of network link types in multiplex networks. To solve this problem, this article considers both link types and agents, and substantially extends the existing work by highlighting the effect of network layers on task allocation and load balancing. Two multiplex network-adapted models of task allocation with load balancing are presented: network layer-oriented allocation and agent-oriented allocation. This article also addresses the unreliability in multiplex networks, which includes the unreliable links and agents, and implements a reliable task allocation based on a negotiation reputation and reward mechanism. Our findings show that both of our presented models can effectively and robustly satisfy the task allocation objectives in unreliable multiplex networks; the experiments prove that they can significantly reduce the time costs and improve the success rate of tasks for multiplex networks over the traditional simplex network-adapted task allocation model. Lastly, we find that our presented network layer-oriented allocation performs much better in terms of reliability and allocation time compared to our presented agent-oriented allocation, which further explains the importance of network layers in multiplex networks.