Creep-rupture reliability analysis

A probabilistic approach to the correlation and extrapolation of creep-rupture data is presented. Time temperature parameters (TTP) are used to correlate the data, and an analytical expression for the master curve is developed. The expression provides a simple model for the statistical distribution of strength and fits neatly into a probabilistic design format. The analysis focuses on the Larson-Miller and on the Manson-Haferd parameters, but it can be applied to any of the TTP's. A method is developed for evaluating material dependent constants for TTP's. It is shown that optimized constants can provide a significant improvement in the correlation of the data, thereby reducing modelling error. Attempts were made to quantify the performance of the proposed method in predicting long term behavior. Uncertainty in predicting long term behavior from short term tests was derived for several sets of data. Examples are presented which illustrate the theory and demonstrate the application of state of the art reliability methods to the design of components under creep

Modeling Wood Moisture Sorption Hysteresis Based on Similarity Hypothesis. Part II. Capillary-Radii Approach

The applicability of Mualem's capillary-radii model to wood moisture sorption hysteresis is evaluated. The model further simplifies the prediction of sorption hysteresis in that scanning curves can be obtained from the moisture content and relative humidity data of the boundary isotherms, with no other intermediate parameters needed. A comparison of predicted moisture contents with actual experimental data points for yellow-poplar (Liriodendron tulipifera) indicates that the model consistently underestimates the primary desorption scanning isotherms, with errors ranging from -0.01 to -1.31. These prediction errors are slightly larger than those obtained from an earlier model based on Mualem's direct similarity hypothesis

Terahertz photoconductivity and plasmon modes in double-quantum-well field-effect transistors

Double-quantum-well field-effect transistors with a grating gate exhibit a sharply resonant, voltage tuned terahertz photoconductivity. The voltage tuned resonance is determined by the plasma oscillations of the composite structure. The resonant photoconductivity requires a double-quantum well but the mechanism whereby plasma oscillations produce changes in device conductance is not understood. The phenomenon is potentially important for fast, tunable terahertz detectors

Evaluation of Three Organic Products With Three Doses for Boat Control (Phytophthora Infestans) in Potato Cultivation (Solanum Tuberosum cv. Fripapa) Riobamba Canton, Chimborazo Province

This research proposes to evaluate three ecological products with three doses for the control disease (Phytophthora infestans) in the potato crop (Solanum tuberosum cv. Fripapa) in the Riobamba canton, Chimborazo province. Three ecological products helped: Citrubact, Fosficarben, and Bioplus in high medium and low doses recommended by the producers, making applications every two weeks in this crop, to determine the best product in both the P. infestans control and performance of growing marginal rate. A design of randomized complete blocks (RCBD) in bifactorial combinations with 9 treatments, 4 replications and a control were used. As a result, the lower incidence of the disease was obtained by Fosficarben treatment in high doses (4cc/Lt) with 8.33%, due to the component ion phosphite, which has a direct effect on the fungal metabolism. The same behaviour was observed in the intensity where Fosficarben in high doses (4cc/Lt) obtained 12,83%, being the lower intensity of the research. The treatment with better performance was also Fosficarben in high doses with 21496, 80l<h/ha. According to the economic analysis the treatment composed by Citrubact in low-doses (lcc/Lt) got a higher marginal rate of return in relation to other treatments of 798.97% and a net income of 2631.28 USD and a variable cost, followed by the Bioplus treatmentdue in medium doses (4cc/Lt) with 765.14% of marginal rate. In conclusion, it is possible to control P. infestans in the potato crop by using ecological products, obtaining a good performance, a healthy product and economic income. Keywords: ecological products, potato crop, control disease. Resumen La presente investigación propone: evaluar tres productos ecológicos con tres dosis para el control de lancha (Phytophthora infestans) en el cultivo de papa (Solanum tuberosum cv. Fripapa) Cantón Riobamba, Provincia de Chimborazo. Ayudándonos de tres productos ecológicos: Citrubact. Fosficarben y Bioplus, en dosis alta media y baja recomendadas por las empresas productoras, realizando aplicaciones cada dos semanas en este cultivo, para determinar el mejor producto, tanto en el control de P. infestans, como en rendimiento del cultivo y tasa de retorno marginal. Se utilizó un diseño de bloques completos al azar (DBCA) en arreglo bifactorial combinatorio, con 9 tratamientos, 4 repeticiones y un testigo. Resultando que la menor incidencia de la enfermedad la obtuvo el tratamiento formado por Fosficarben en dosis alta (4cc/lt) con 8,33%, esto se debe a que contiene ion fosfito, que ejerce un efecto directo sobre el metabolismo fúngico. El mismo comportamiento se pudo observar en la intensidad donde Fosficarben en dosis alta (4cc/lt) obtuvo 12,83% siendo la menor intensidad del estudio. El tratamiento con mayor rendimiento también fue Fosficarben en dosis alta (4cc/lt) con 21496,80 kg/ha. En al análisis económico el tratamiento formado por Citrubact en dosis baja (1 cc/lt) obtuvo una mayor tasa de retorno marginal en relación al resto de tratamientos de 798,97%, con un beneficio neto de 2631,28 USD y un costo variable de 177,55 USD; debido a su dosis baja, es el más rentable de los tratamientos en estudio, seguido por el tratamiento conformado por Bioplus en dosis media (4 cc/lt) con 765,14% de tasa de retorno marginal. En conclusión se puede controlar a P. infestans en el cultivo de papa utilizando productos ecológicos, obteniendo un buen rendimiento, un producto sano y generando ingresos económicos. Palabras clave: productos ecológicos, cosecha de papas, control de enfermedades

Divergence-type 2+1 dissipative hydrodynamics applied to heavy-ion collisions

We apply divergence-type theory (DTT) dissipative hydrodynamics to study the 2+1 space-time evolution of the fireball created in Au+Au relativistic heavy-ion collisions at $\sqrt{s_{NN}}=$200 GeV. DTTs are exact hydrodynamic theories that do no rely on velocity gradient expansions and therefore go beyond second-order theories. We numerically solve the equations of motion of the DTT for Glauber initial conditions and compare the results with those of second-order theory based on conformal invariants (BRSS) and with data. We find that the charged-hadron minumum-bias elliptic flow reaches its maximum value at lower $p_T$ in the DTT, and that the DTT allows for a value of $\eta/s$ slightly larger than that of the BRSS. Our results show that the differences between viscous hydrodynamic formalisms are a significant source of uncertainty in the precise extraction of $\eta/s$ from experiments.Comment: v4: 29 pages, 12 figures, minor changes. Final version as published in Phys. Rev.

Study of the stress intensity factors in the bulk of the material with synchrotron diffraction

Artículo de Proceedings de Congreso Internacional Fatigue2017In this work we present the results of a hybrid experimental and analytical approach for estimating the stress intensity factor. It uses the elastic strains within the bulk obtained by synchrotron X-ray diffraction data. The stress intensity factor is calculated using a multi-point overdeterministic method where the number of experimental data points is higher than the number of unknowns describing the elastic field surrounding the crack-tip. The tool is tested on X-ray strain measurements collected on a bainitic steel. In contrast to surface techniques the approach provides insights into the crack tip mechanics deep within the sample.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. The authors are grateful to the ESRF for ID15 beamtime awarded under MA-1483. Financial support of Universidad de Malaga through Plan Propio, Junta de Andalucía through Proyectos de Excelencia grant reference TEP-3244, Campus de Excelencia Internacional del Mar (CEIMAR) and Ministerio de Economia y Competitividad through grant reference MAT2016-76951-C2-2-P is also acknowledged. PJW acknowledges an ERC advanced grant

Cortical Bone Thickness Assessment from Multi-frequency Ultrasound RF Data using a Convolutional Architecture with Multi-head Attention

Cortical bone thickness is an important predictor of bone strength and fracture risk, and accurate classification is crucial for the diagnosis and treatment of osteoporosis. The thinning of the cortical layer, indicative of compromised bone microarchitecture due to imbalanced formation and loss, underscores its significance. Nonetheless, quantifying bone thickness is challenging due to the diverse skeletal sites and subject variations in bone structure and properties.A potential solution lies in multi-frequency ultrasound assessment of cortical bone, enabling comprehensive property characterization across varying wavelengths and penetration depths. This research strives to establish a robust methodology for evaluating cortical bone thickness by leveraging a convolutional model with an attention mechanism to analyse multi-frequency ultrasound data

Optimizing conjunctive use under sustained yield constraints

Distributed parameter groundwater management model utilizing quadratic programming to develop a steady-state potentiometric surface is presented. Minimization of cost of meeting water needs from groundwater and alternative water sources is achieved. Drawdowns, groundwater withdrawal and recharge are all constrained. Applicable for assuring agregiorral sustained yield of groundwater