Mixed Path Research Articles

Mixed Mode Crack Growth in Functionally Graded Material Under Three-Point Bending

Functionally graded materials, FGM, permit tailoring the material volume fractions to extract maximum benefit from their in-homogeneity. Such materials offer great potential for components, which operate under severe thermal or mechanical loadings, such as spacecraft heat shields, plasma facings for fusion reactors, crucial jet fighter structures and engine components. In the present work, polyester matrix reinforced by varying glass fiber distribution was used to obtain FGM polymeric composites. The hand lay-up technique was adopted to manufacture the FGM. The mixed mode crack path of glass fiber/polyester FGM under three point bend, 3PB, was observed. The mechanical properties, such as tensile and flexural strength were determined experimentally and numerically. Pre-cracks with different lengths and locations with seven different inclination angles were considered to study the mixed mode crack growth of FGM. For the same crack length, the present results showed that the maximum applied load increased with increasing the crack inclination angle, i.e. the mode of mixity increased to reach pure mode II. Generally, the crack path initiated from the original inclination angle and grew along a curvilinear trajectory to extend toward the upper loading point.

Análise biométrica de clones de mandioca

In the last ten years cassava roots represented the fourth most produced commodity in Brazil. Given its commercial importance, higher yields are constantly sought in breeding programs. This study was aimed at conducting a biometric analysis of cassava clones based on the estimation/prediction of genetic parameters and correlated genetic gain using mixed models and path analysis, respectively. Forty-eight clones were evaluated in a randomized block design with two replicates. The experiment was carried out in northern Minas Gerais in 2010. The agronomic characteristics evaluated were plant height (PH), fresh weight of aerial parts (FWAP), fresh root weight (FRW), fresh weight of commercial roots (FWCR), root length (RL), and root diameter (RD). These traits were evaluated at six and twelve months after planting. All traits examined were significantly affected by genotype. FWAP, RL and RD changed according the time of harvesting and RL was superior at six months. Accuracy was highest for PH (0.90) and lowest for FRW and FWCR (0.64). UFLA 42 was the most commercially productive. The trait RL exhibited the highest gain via correlated response to FWCR at twelve months after planting. At six months after planting, no traits were suitable for indirect selection. The traits PH and FWAP had little relevance as secondary components in path analysis.

Effect of Mixed Propagation Path on Electromagnetic Fields at Ground Surface Produced by Electrojet

The effect of a mixed propagation path on the ground-surface electromagnetic fields generated by an electrojet is evaluated. To this aim, the finite element method is used for two-dimensional modeling of the problem. Results are first obtained for the case of horizontally stratified ground and compared with those obtained by the use of the complex-image method. Then, the ground-surface electromagnetic fields are calculated for two types of the mixed propagation path, namely the vertically horizontally multilayer ground and the ocean–land propagation path. It is shown that such paths can affect the electromagnetic fields at the ground surface. This effect is more pronounced for the case of the ocean–land propagation path.

An inverse eigenvalue problem for pseudo-Jacobi matrices

In this paper, the theory on direct and inverse spectral problems for Jacobi matrices is revisited in a kind of pseudo-Jacobi matrices J(n,r,β) with a mixed path as its graph in the non-self-adjoint setting. In this context, a sign change in one of the nondiagonal entries of the matrix yields strong perturbations in its spectral properties. The reconstruction of a pseudo-Jacobi matrix from its spectrum and the spectra of two complementary principal matrices is investigated. An algorithm for the reconstruction of matrices from prescribed spectral data is provided and illustrative numerical experiments are performed.

Performance Evaluation of Advanced Relaying Protocols in Large Wireless Networks

This paper studies the performance of some state-of-the-art cooperative full-duplex relaying protocols in the context of a large wireless network modeled using stochastic geometry tools. We investigate the outage behavior for different cooperative schemes, namely decode-and-forward, noisy-network coding, and mixed noisy-network coding, considering fading, path loss, and interference from other sources and relays. Due to the high complexity of the network topology and the protocols considered, a closed-form analysis is not possible, so our study is performed through extensive but careful numerical simulations, sweeping a large number of relevant parameters. Several scenarios of particular interest are investigated. In this way, insightful conclusions are drawn regarding the network regimes in which relay-assisted cooperation is most beneficial and the potential gains that could be achieved through it.

Numerical and analytical modeling of crack path for three-dimensional mixed mode crack problem using global approach

Civil engineering and mechanical structures are usually submitted to mixed mode loading. Consequently, a mixed mode crack path process occurs. In three-dimensional crack problem, the study of this problem is very important due to multiple problems that require more understanding of the corner point effect and the local effect due to the torsion mode (mode III) and also due to the necessity to take into account thickness effect. In order to study the mixed mode loading for three-dimensional crack problem, a new three-dimensional contour integral entitled M3D integral is modeled using global approach. Combining real and virtual mechanical displacement fields, this new integral is used to separate numerically mode I, mode II and mode III in the mixed mode ratio. In earlier research works, Moutou Pitti et al [1] have proposed a new specimen called Mixed Mode Crack Growth (MMCG), and El kabir et al [2] have studied numerically the stability of this specimen for various geometries in two-dimensional case. This work deals with numerical and analytical modeling to study the crack path stability in real three-dimensional case for mixed mode crack problem. Using MMCG specimen, the non-dependence of integration domain is presented, and the stability of the calculation of M3D Integral with respect to various geometries and thicknesses is shown for the opening mode (Mode I), the shear mode (Mode II), the out-of-plan shear mode (Mode III) and also for the mixed mode ratio by computing the energy release rate versus the crack length. Finally, the analytical generalization of the M3D-integral is done. That will allow to take into account the mixed-mode crack growth analysis coupling mechanical and thermal loads.

Triaxial experimental study of concrete with control of one stress and two strains

The behaviour of cubic concrete specimens (100 × 100 × 100 mm) subjected to a mixed path of both stress and strain loading was investigated. The specimens were statically loaded in a true triaxial apparatus. Three different values of the minimum principal stresses were chosen (10, 15 and 20 MPa). In addition, for each value of the minimum principal stress, three or four strain rate ratios between the x-axis and the y-axis were used (0·25, 0·5, 0·75 and 1·0). The first and second peak stresses occurred in the maximum principal strain axis (y-axis) and the intermediate principal strain axis (x-axis), respectively. The maximum principal stress and the intermediate principal stress did not always exist in a fixed axis, which is related to the strain rate ratios. Some damage formed due to previous load histories, including the peak stress of the y-axis, results in a decreased load carrying capacity in the x-axis. Therefore, the peak stress of the intermediate principal strain axis (x-axis) was lower than that of the maximum principal strain axis (y-axis). Moreover, the y-axis strain corresponding to the first peak stress and the x-axis strain corresponding to the second peak stress were essentially equal. It was found that there is a limit state in concrete: if the strain difference between y- and z-axes and between x- and z-axes is large enough, the load carrying capacities of the y- and x-axes are the same, with the value related to the minimum principal stress and independent of the strain rate ratio.

HPV status is associated with fatigue and inflammation in patients with squamous cell carcinoma of the Head and Neck from pre to up to 3 Months Post IMRT

This longitudinal study examined associations among HPV, inflammation and fatigue in head and neck cancer (HNC) patients receiving intensity-modulated radiation therapy (IMRT). Consented patients were followed pre-, one-month and three-month post-IMRT. Fatigue was assessed by the Multidimensional Fatigue Inventory-20. Plasma interleukin-1receptor antagonist (IL-1ra) and soluble tumor necrosis factor receptor2 (sTNFR2) were determined using Magnetic Luminex Screening Assay; acute phase proteins (CRP) were determined using a standard turbidimetric assay. Mixed effect modeling and path analysis were used to examine the associations. Ninety-four patients with newly diagnosed, locally advanced non- metastatic HNC were enrolled from 2012 to 2015; majority received concurrent chemoradiotherapy (CRT). Fifty-three percent of them were HPV+. HPV+ patients were more likely to be male, have no history of tobacco use, have higher BMI, be diagnosed with oropharyngeal cancer, and receive CRT. HPV+ patients had significant lower fatigue, and lower inflammation as represented by CRP (p

Network Pricing of Congestion-Free Networks: The Elastic and Linear Demand Case

In this work, we address the problem of maximizing the revenue raised from tolls set on a multicommodity transportation network, taking into account that users are assigned to cheapest paths, and that demand is a linearly decreasing function of total path cost (initial cost of carrying the products plus toll). We propose for its numerical solution three mixed quadratic formulations, either in arc or path flow space. Similar to what was achieved in the fixed demand case, we analyze the structure and properties of the problem, including its theoretical complexity. On the computational side, we analyze the sensitivity of central processing unit time with respect to two key parameters, namely, demand elasticity and percentage of toll arcs.

The Cortisol Awakening Response Mediates the Relationship Between Acculturative Stress and Self-Reported Health in Mexican Americans.

The assessment of acculturative stress as synonymous with acculturation level overlooks the dynamic, interactive, and developmental nature of the acculturation process. An individual's unique perception and response to a range of stressors at each stage of the dynamic process of acculturation may be associated with stress-induced alterations in important biological response systems that mediate health outcomes. Evidence suggests the cortisol awakening response (CAR) is a promising pre-clinical biomarker of stress exposure that may link acculturative stress to self-reported health in Mexican Americans. The aim of the current study was to examine whether alterations in the CAR mediate the relationship between acculturative stress and self-reported health in Mexican Americans. Salivary cortisol samples were collected at awakening, 30, 45, and 60min thereafter, on two consecutive weekdays from a sample of adult Mexican Americans. Acculturative stress and self-reported health were assessed. Data were aggregated and analyzed (n=89) using a mixed effects regression model and path analysis. Poorer self-reported health was associated with attenuated CAR profiles (primarily due to a diminished post-awakening rise in cortisol) predicted by both moderate and high levels of exposure to acculturative stress. Stress-induced alterations in the CAR mediated the relationship between exposure to acculturative stressors and self-reported health. Findings demonstrate that different levels of acculturative stress are associated with distinct CAR profiles and suggest the CAR is one possible biological pathway through which exposure to culturally unique stressors may be linked to health disparities.

Path Loss Channel Model for Inland River Radio Propagation at 1.4 GHz

In this paper, a propagation path loss model for inland river is proposed by three improvements compared with the Round Earth Loss (REL) model for open-sea environment. Specifically, parameters optimization uses Okumura-Hata model in dB scale to replace the equation transformed from the free space loss in REL model; secondly, diffraction loss caused by the obstacles (e.g., large buildings, bridges, or some other facilities near the river bank) is also taken into account; mixed-path methodology as another improvement is used for Inland River (IR) model because the actual propagation environment between transmitter (TX) antenna and receiver (RX) antenna contains both land part and water part. The paper presents a set of 1.4 GHz measurements conducted along the Yangtze River in Wuhan. According to the comparison between path loss models and experimental results, IR model shows a good matching degree. After that, Root Mean Square Error (RMSE), Grey Relation Grade and Mean Absolute Percentage Error (GRG-MAPE), Pearson Correlation Coefficient, and Mean Absolute Percentage Error (PCC-MAPE) are employed to implement quantitative analysis. The results prove that IR model with consideration of mixed path and deterministic information is more accurate than other classic empirical propagation models for these scenarios.

Thermal Cycling Behavior of Thermal Barrier Coatings with MCrAlY Bond Coat Irradiated by High-Current Pulsed Electron Beam.

Microstructural modifications of a thermally sprayed MCrAlY bond coat subjected to high-current pulsed electron beam (HCPEB) and their relationships with thermal cycling behavior of thermal barrier coatings (TBCs) were investigated. Microstructural observations revealed that the rough surface of air plasma spraying (APS) samples was significantly remelted and replaced by many interconnected bulged nodules after HCPEB irradiation. Meanwhile, the parallel columnar grains with growth direction perpendicular to the coating surface were observed inside these bulged nodules. Substantial Y-rich Al2O3 bubbles and varieties of nanocrystallines were distributed evenly on the top of the modified layer. A physical model was proposed to describe the evaporation-condensation mechanism taking place at the irradiated surface for generating such surface morphologies. The results of thermal cycling test showed that HCPEB-TBCs presented higher thermal cycling resistance, the spalling area of which after 200 cycles accounted for only 1% of its total area, while it was about 34% for APS-TBCs. The resulting failure mode, i.e., in particular, a mixed delamination crack path, was shown and discussed. The irradiated effects including compact remelted surface, abundant nanoparticles, refined columnar grains, Y-rich alumina bubbles, and deformation structures contributed to the formation of a stable, continuous, slow-growing, and uniform thermally grown oxide with strong adherent ability. It appeared to be responsible for releasing stress and changing the cracking paths, and ultimately greatly improving the thermal cycling behavior of HCPEB-TBCs.

In unison: First- and second-order information combine for integration of shape information.

The modulation of orientation around radial frequency (RF) patterns and RF textures is globally processed in both cases. This psychophysical study investigates whether the combination-a textured RF path obtained by applying an RF texture to an RF contour-is processed like a texture or a contour when making judgements about shape. Unlike RF textures, the impression of a closed flow was not required for global integration of textured RF paths, suggesting that these paths were processed as second-order, or contrast-defined contours. Luminance-defined (LD) RF paths were shown to globally integrate but with thresholds approximately half of those for the proposed second-order textured paths. The next experiment investigated whether this benefit was due to LD stimuli possessing double the amount of information (first- and second-order information). A mixed three-part contour composed of two different second-order texture components and an LD component was then employed to determine how the different cues combined. The mixed path thresholds matched predictions derived from a linear combination of first- and second-order cues. The conclusion is that the shape of isolated contours is processed using both first- and second-order information equally and that the contribution of texture is to carry additional second-order signal.

Vertical Trajectory Optimization to Minimize Environmental Impact in the Presence of Wind

The vertical trajectory optimization for the en route descent phase is studied in the presence of both along-track and cross winds, which are both modeled as functions of altitude. The flight range covers some portion of a cruise segment and ends at a meter fix. The descent trajectory is assumed as a flight idle descent. The problem is formulated as an optimal control problem with both mixed state path constraints and pure state constraints. For minimizing environmental impacts, we optimize descent trajectory with respect to two cost functionals: fuel and emissions costs. We analyze both singular arc and boundary arc using the necessary conditions of the optimality. From the analysis result, we propose the optimal trajectory generation method, in which the optimal trajectory is generated by the backward and forward integration. The trajectory from the proposed algorithm is compared with the numerical optimal solution of the original optimal control problem. The result shows that the proposed algorithm generates the same solution as the numerical optimal solution. The wind speed, windshear, and cross-wind effects on the optimal trajectory are analyzed with two aircraft type, Boeing 737-500 and Boeing 767-400.

Combining self-management cues with incentives to promote interdental cleaning among Indian periodontal disease outpatients.

BackgroundPeriodontal disease is a significant public health issue worldwide. Motivational techniques in combination with financial incentives are shown to lead to effective behavior change. The current study sought to examine whether a brief oral health promotion program (self-management cues that were based on self-efficacy and self-regulatory skills) in combination with an incentive (free dental treatment) would make a difference in the adoption of regular dental flossing in a population of Indian periodontal disease outpatients.MethodsOne hundred and twelve participants (n = 55 oral health promotion intervention group; n = 57 control group) were assigned to the intervention (self-management cues + incentive) or control groups, and follow-up assessments were performed three weeks later. Flossing frequency, behavioral intentions, and perceived self-efficacy served as dependent variables. Data were analyzed with mixed models, ANCOVAs, and path analyses.ResultsThe intervention yielded effects on flossing frequency (p < 0.01) and flossing intentions (p < 0.01) at follow-up. Women developed stronger intentions than men. Moreover, by path analysis a sequential mediation chain was found that demonstrated an indirect effect of the intervention on flossing via self-efficacy and intentions: the intervention predicted changes in self-efficacy which, in turn, were associated with changes in intentions, predicting flossing frequency at follow up, while controlling for baseline behavior, gender, and age.ConclusionsCombining incentives with minimal self-management cues has been found effective in improving interdental cleaning intentions and habits in periodontal disease patients, and the facilitating role of dental self-efficacy has been demonstrated.

Flight formation of UAVs in presence of moving obstacles using fast-dynamic mixed integer linear programming

This paper proposes the implementation of fast-dynamic Mixed Integer Linear Programming (MILP) and Path Smoother for efficient path planning of Unmanned Aerial Vehicles (UAVs) in various flight formations. The UAVs taking part in a cooperative flight are assumed to be equipped with Automatic Dependent Surveillance Broadcast (ADS-B) which enables sharing the flight information with neighboring aircraft. The design and implementation of flights for various formations have been carried out in a generic manner such that multiple UAVs with arbitrarily geographically located base stations can take part in collision-free formation flight. The paper formulates the problem of path of planning in the framework of a novel fast-dynamic MILP and proposes a cost function that minimizes time and energy consumption. The paper presents elaborate construction of constraint equations to enforce the formation to visit pre-defined way-points and avoid the collisions with any intruder aircraft. The performance of the proposed algorithm has been verified and compared with respect to the standard MILP method via a number of simulations carried out using different scenarios featuring multiple UAVs flying in various formations.

Physical fitness differences between rural and urban children from western Kenya.

To study the effects of urbanization on physical fitness (PF), we compare PF between urban and rural children from western Kenya. We hypothesize that active rural children are stronger, more flexible, and have greater endurance, and that PF differences are predictive of endurance running performance. We recruited an age-matched, cross-sectional sample of participants (55 males, 60 females; 6-17 years) from schools near Eldoret, Kenya. PF and anthropometrics were assessed using the FITNESSGRAM®. General linear mixed models (GLMM) and path analyses tested for age, sex, and activity group differences in PF, as well as the effects of PF variables on mile run time. On average, urban participants had greater body mass (36.8 ± 15.9 vs. 31.9 ± 10.9 kg) but were not taller than rural participants (1.4 ± 0.2 vs. 1.4 ± 0.2 cm). Greater urban body mass appears driven by higher body fat (28.2 ± 9.4 vs. 16.8 ± 4.4%), which increased with age in urban but not rural participants. GLMM analyses showed age effects on strength variables (P<0.05) and sex differences in hip flexibility, sit-ups, and mile run (P<0.05). There were few differences in PF between groups except rural participants had stronger back muscles (18.2 ± 4.5 vs. 14.18 ± 4.3 cm) and faster mile times (6.3 ± 0.7 vs. 7.9 ± 2.0 min). Body composition and abdominal strength were predictive of mile time (P < 0.06), but the path analysis revealed a network of interacting direct and indirect effects that influenced endurance performance. Although differences in endurance and body composition are marked between urban and rural groups, strength and flexibility are not always correlated with overall activity levels. Am. J. Hum. Biol. 28:514-523, 2016. © 2015 Wiley Periodicals, Inc.

3-D FDTD Simulation of the Lightning-Induced Waves on Overhead Lines Considering the Vertically Stratified Ground

In this paper, we have employed the 3-D finite-difference time-domain technique to analyze the influence of the vertically stratified conducting ground (mixed path) on the lightning-induced voltages of the overhead line at 60 and 200 m from the lightning strike point by using decomposing method. In order to analyze the effect range caused by mixed path, we assumed that the mixed path has much different conductivities with 100:1 ratio. When the conductivity near the strike point (0.1 S/m) is larger than that near the overhead line section (0.001 S/m), the induced voltage clearly increases with the increase of the closest distance from the center of the line to the interface between the two media ( dl ). However, for strike point with a less conducting earth (0.001 S/m) than the overhead line section (0.1 S/m), when dl is less than 30 m, the influence of the stratification should be considered; when dl is larger than 30 m, it can just be regarded as a homogeneous soil with the conductivity of 0.1 S/m equal to that near the overhead line. For the smaller ratio of conductivities of the mixed path, its effect on the induced voltages decreases.

The Influence of the Slope Angle of the Ocean–Land Mixed Propagation Path on the Lightning Electromagnetic Fields

In this paper, lightning electromagnetic fields in the presence of an ocean–land mixed propagation path having different configurations are evaluated using a finite-element-based full-wave approach. The simulations are conducted considering lightning strikes to ground and to the ocean. The lightning electromagnetic fields are obtained for observation points inside the ground and on the ground surface. The land–ocean interface is represented by a linearly increasing ocean depth characterized by the slope angle. Different sets of simulation results show that the electric field components (vertical and horizontal) in the immediate vicinity of the interface can be affected by the interface slope angle. The obtained results also show that, for observation points located beyond 50 m or so from the ocean, the effect of the slope angle of the ocean–land interface on the lightning electromagnetic fields can be disregarded.

On the Development of a High-Frequency Radar Cross Section Model for Mixed Path Ionosphere–Ocean Propagation

An analytic high-frequency (HF) radar cross section model for ionosphere–ocean propagation is presented. Based on earlier work, an expression for the first-order received electric field after a single scatter from each of the ionosphere and sea surface is derived and reduced to integral form. The field integrals are taken to the time domain, with the source field being that of a vertically polarized pulsed dipole antenna. Subsequently, the first-order radar cross section for the mixed path mode of ionospheric clutter is developed. The ionosphere reflection coefficient used in the analysis is assumed to be a stochastic process with an associated spectral density function to account for phase variations along the surface associated with nonuniformity of the signal path. Simulation results for the new cross section are also provided. It is shown numerically that the expected magnitude of the ionosphere clutter, under reasonable assumptions, exceeds the dominant first-order ocean clutter for the same apparent range by 50–60 dB. Further, it is spread in Doppler, depending on the ionosphere horizontal velocity and reflecting path nonuniformity. Also, this component can be presented from a certain minimum range, depending on ionosphere virtual height, to the maximum radar range.