Analytical, experimental and numerical study of a graded honeycomb structure under in-plane impact load with low velocity

Given the significance of energy absorption in various industries, light shock absorbers such as honeycomb structure under in-plane and out-of-plane loads have been in the core of attention. The purpose of this research is the analyses of graded honeycomb structure (GHS) behaviour under in-plane impact loading and its optimisation. Primarily, analytical equations for plateau stress and specific energy are represented, taking power hardening model (PHM) and elastic–perfectly plastic model (EPPM) into consideration. For the validation and comparison of acquired analytical equations, the energy absorption of a GHS made of five different aluminium grades is simulated in ABAQUS/CAE. In order to validate the numerical simulation method in ABAQUS, an experimental test has been conducted as the falling a weight with low velocity on a GHS. Numerical results retain an acceptable accordance with experimental ones with a 5.4% occurred error of reaction force. For a structure with a specific kinetic energy, the stress–strain diagram is achieved and compared with the analytical equations obtained. The maximum difference between the numerical and analytical plateau stresses for PHM is 10.58%. However, this value has been measured to be 38.78% for EPPM. In addition, the numerical value of absorbed energy is compared to that of analytical method for two material models. The maximum difference between the numerical and analytical absorbed energies for PHM model is 6.4%, while it retains the value of 48.08% for EPPM. Based on the conducted comparisons, the numerical and analytical results based on PHM are more congruent than EPPM results. Applying sequential quadratic programming method and genetic algorithm, the ratio of structure mass to the absorbed energy is minimised. According to the optimisation results, the structure capacity of absorbing energy increases by 18% compared to the primary model

QT dispersion in patients with systemic lupus erythematosus: the impact of disease activity

<p>Abstract</p> <p>Background</p> <p>Patients with systemic lupus erythematosus (SLE) have increased cardiovascular morbidity and mortality. Although autopsy studies have documented that the heart is affected in most SLE patients, clinical manifestations occur in less than 10%. QT dispersion is a new parameter that can be used to assess homogeneity of cardiac repolarization and autonomic function. We compared the increase in QT dispersion in SLE patients with high disease activity and mild or moderate disease activity.</p> <p>Methods and Results</p> <p>One hundred twenty-four patients with SLE were enrolled in the study. Complete history and physical exam, ECG, echocardiography, exercise test and SLE disease activity index (SLEDAI) were recorded. Twenty patients were excluded on the basis of our exclusion criteria. The patients were divided to two groups based on SLEDAI: 54 in the high-score group (SLEDAI > 10) and 50 in the low-score group (SLEDAI < 10).</p> <p>QT dispersion was significantly higher in high-score group (58.31 ± 18.66 vs. 47.90 ± 17.41 respectively; <it>P </it>< 0.004). QT dispersion was not significantly higher in patients who had received hydroxychloroquine (54.17 ± 19.36 vs. 50.82 ± 15.96, <it>P </it>= 0.45) or corticosteroids (53.58 ± 19.16 vs. 50.40 + 11.59, <it>P </it>= 0.47). There was a statistically significant correlation between abnormal echocardiographic findings (abnormalities of pericardial effusion, pericarditis, pulmonary hypertension and Libman-Sacks endocarditis) and SLEADI (<it>P </it>< 0.004).</p> <p>Conclusions</p> <p>QT dispersion can be a useful, simple noninvasive method for the early detection of cardiac involvement in SLE patients with active disease. Concerning high chance of cardiac involvement, cardiovascular evaluation for every SLE patient with a SLEDAI higher than 10 may be recommended.</p> <p>Trial registration</p> <p>Clinicaltrial.gov registration <a href="http://www.clinicaltrials.gov/ct2/show/NCT01031797">NCT01031797</a></p

State-of-the-art of spatial arch bridges

The paper describes a new form of bridge called a spatial arch bridge. This bridge type was developed in response to the demand for landmark structures, which have started to appear in the modern urban landscape to provide a symbol of originality, innovation and progress. Spatial arch bridges are defined as bridges in which the vertical deck loads produce bending moments and shear forces not contained in the arch plane, owing to their geometrical and structural configuration. Moreover, the arch itself may not be contained in a plane. The different variables and geometries that create such a structural configuration have been studied and classified. A wide compilation of examples of this bridge type has been made in chronological order, according to their construction date, from Maillarts first concrete spatial arch bridges to the latest designs and materials

Epidemiological study on some environmental and management parameters affecting on WSD occurrence in Fenneropenaeus indicus and Penaeus vannamei

For the first time white spot disease (WSD) was reported in shrimp farms of khoozestan province, in southwest of IRAN in 2002. Then in 2005 the neighbor province, boushehr, was contaminated. In 2008 WSD outbreak reported in sistan-bloochestan province in southeast of Iran. In 2015 all of southern shrimp farms of country except Hormozgan, the middle southern province, which has remained free of WSD, are being contaminated. White Spot disease suspended shrimp culture in thousands hectares of shrimp farms. Considering that white spot disease has not been observed in Hormozgan province yet, the question is; to what extent environmental and management factors participated in preventing WSD outbreak or cause WSD outbreak. In this study (20102012), the effects of environmental factors and management, stressors that decrease immune system function of shrimp are discussed. In addition, the role of pathogen as the main factor of outbreak is discussed. The goal of this study is to define environmental parameters and management practices associates with outbreak of white spot disease in affected provinces and discover reasons of being Hormozgan province free of this disease. In this study the role of the local environmental factors and management practice stressors in susceptibility to WSD was determine. Both the effects of environmental factors in water of ponds including total ammonia, nitrogen, dissolved oxygen, pH, salinity, transparency, and temperature and management issues related to biosecurity are studied. There were overlaps on physical and chemical parameter values obtained in clear areas with contaminated areas .Results of the data analysis suggest that lack of association with WSD incidence was 7 times greater than WSD incidence despite of disease outbreak in sistan-bloochestan province, so other sources of white spot disease virus incidence was suspected in affected areas. Histopathological examinations and polymerase chain reaction (PCR) tests during project performance did not reveal white spot disease virus evidences in post larvae examined from khoozestan province stocked in farms but disease outbreak was happened in that farms , so we suspected to management practice include feed , pond preparation and carrier of disease. Recorded values of temperature and salinity in some months during inspection in Hormozgan province specified stressful condition that may lead to WSD outbreak, however the disease did not appear. Therefore the hypothesis that the water physical and chemical conditions are reasons to prevent disease outbreak in Hormozgan province is being rejected. The policy of Hormozgan’s fishery authorities, to replaced Fenneropenaeus indicus with specific pathogen free Litopenaeus vannamei, that is more resistant to some of diseases, before incidence of WSD in farms and to before being endemic in the Hormozgan province, made an advantage compare to affected southern provinces that introduced Litopenaeus vannamei after WSD prevalence to their farms. However it does not guarantee to maintain current trend of being Hormozgan province farms free of white spot disease. Therefore establishing the principals of biosecurity are strongly emphasized. Strategies taken by the proficient authorities in preparation of SPF shrimp broodstock can be the most important factor in preventing WSD. Regarding biosecurity principals purchased feed must be free of shrimp head powder. Construction the new shrimp farms should be as far as it could be away from contaminated areas

Evaluación de modelos para estimar la infiltración y rugosidad del riego por surcos

Several methods have been proposed for estimating infiltration and roughness parameters in surface irrigation using mathematical models. The EVALUE, SIPAR_ID, and INFILT models were used in this work. The EVALUE modeluses a direct solution procedure, whereas the other two models are based on the inverse solution approach. The objective of this study is to evaluate the capacity of these models to estimate the Kostiakov infiltration parameters and the Manning roughness coefficient in furrow irrigation. Twelve data sets corresponding to blocked-end and free drainingfurrows were used in this work. Using the estimated  parameters and the SIRMOD irrigation simulation software, the total infiltrated volume and recession time were predicted to evaluate the accuracy of the mathematical models. TheEVALUE and SIPAR_ID models provided the best performance, with EVALUE performing better than SIPAR_ID for estimating the Manning roughness coefficient. The INFILT model provided lower accuracy in cut-back irrigation than in standard irrigation. The performance of SIPAR_ID and INFILT in blocked-end and free draining furrows was similar.En el riego por superficie se han propuesto varios m&eacute;todos basados en modelos matem&aacute;ticos para estimar los&nbsp; par&aacute;metros de infiltraci&oacute;n y rugosidad. En este trabajo se han utilizado los modelos EVALUE, SIPAR_ID e INFILT. El modelo EVALUE utiliza un procedimiento de soluci&oacute;n directa, mientras que los otros dos se basan en un enfoque de soluci&oacute;n inversa. El objetivo de este estudio fue evaluar la capacidad de estos modelos para estimar los par&aacute;metros deinfiltraci&oacute;n de Kostiakov y el coeficiente de rugosidad de Manning en el riego por surcos. Se utilizaron en doce evaluaciones de riego por surcos, bien bloqueados en el extremo o bien con desag&uuml;e libre. Utilizando los par&aacute;metros estimados y el software de simulaci&oacute;n de riego por gravedad SIRMOD, se predijeron el volumen total infiltrado y el tiempo de receso para evaluar la precisi&oacute;n de los modelos&nbsp; matem&aacute;ticos. Los modelos EVALUE y SIPAR_ID proporcionaronel mejor rendimiento, dando mejores resultados EVALUE que SIPAR_ID para estimar el coeficiente de rugosidad de Manning. El modelo INFILT fue menos preciso en el riego con recorte de caudal que en el riego est&aacute;ndar. El rendimiento de SIPAR_ID e INFILT fue similar en los surcos bloqueados en el extremo y con desag&uuml;e libre

A Study of the Formation of Velocity Counter Lines and Secondary (Spiral) Flows in Different Cross Sections of Divergent, Convergent and Uniform Arcs

The mechanical properties of flow are very complex in channel arcs. Therefore, dynamic numerical models of fluids are considered effective tools in predicting such flow fields. In this study, the numerical model was validated by the measures of a uniform U-shaped arc with a width of 0.6 meter. Then two similar U shaped arcs, divergent and convergent, were simulated by a three-dimensional numerical model with variable widths from 0.6 to 0.75 meters and 0.6 to 0.45 meters. Validating the numerical model by measured data in the uniform 180-degree arc showed that the model can simulate the flow field in the uniform arc very well. Results regarding several parameters such as rout of maximum velocity, maximum velocity line, water level variations, power of spiral flow, existence of a rotating cell are stated and discussed

D‌E‌V‌E‌L‌O‌P‌M‌E‌N‌T O‌F A M‌E‌T‌H‌O‌D F‌O‌R D‌E‌T‌E‌R‌M‌I‌N‌A‌T‌I‌O‌N O‌F L‌O‌C‌A‌T‌I‌O‌N O‌F M‌A‌X‌I‌M‌U‌M S‌H‌E‌A‌R S‌T‌R‌E‌S‌S I‌N R‌I‌V‌E‌R B‌E‌N‌D‌S (V‌E‌R‌I‌F‌I‌C‌A‌T‌I‌O‌N O‌F R‌E‌P‌O‌R‌T N‌O. 592, I‌R‌A‌N‌I‌A‌N E‌N‌E‌R‌G‌Y M‌I‌N‌I‌S‌T‌R‌Y

H‌y‌d‌r‌a‌u‌l‌i‌c c‌o‌n‌d‌i‌t‌i‌o‌n‌s a‌n‌d i‌d‌e‌n‌t‌i‌f‌i‌c‌a‌t‌i‌o‌n o‌f r‌e‌a‌c‌h b‌a‌s‌e‌d o‌n w‌h‌i‌c‌h m‌a‌x‌i‌m‌u‌m s‌h‌e‌a‌r s‌t‌r‌e‌s‌s o‌c‌c‌u‌r‌s a‌r‌e v‌e‌r‌y c‌o‌m‌p‌l‌e‌x p‌r‌o‌b‌l‌e‌m‌s i‌n r‌i‌v‌e‌r b‌e‌n‌d‌s. I‌n t‌h‌i‌s r‌e‌s‌e‌a‌r‌c‌h, a m‌e‌t‌h‌o‌d i‌s d‌e‌v‌e‌l‌o‌p‌e‌d f‌o‌r d‌e‌t‌e‌r‌m‌i‌n‌i‌n‌g t‌h‌e l‌o‌c‌a‌t‌i‌o‌n o‌f t‌h‌i‌s r‌e‌a‌c‌h i‌n b‌e‌n‌d‌s. I‌n a‌d‌d‌i‌t‌i‌o‌n, r‌e‌s‌u‌l‌t‌s o‌f t‌h‌i‌s m‌e‌t‌h‌o‌d a‌r‌e c‌o‌m‌p‌a‌r‌e‌d t‌o i‌n‌s‌t‌r‌u‌c‌t‌i‌o‌n‌s o‌f r‌e‌p‌o‌r‌t N‌o. 592 (p‌r‌e‌p‌a‌r‌e‌d b‌y I‌r‌a‌n‌i‌a‌n M‌i‌n‌i‌s‌t‌r‌y o‌f E‌n‌e‌r‌g‌y). D‌o‌w‌n‌s‌t‌r‌e‌a‌m o‌f t‌h‌e K‌a‌r‌k‌h‌e‌h d‌a‌m i‌s t‌h‌e c‌a‌s‌e s‌t‌u‌d‌y o‌f t‌h‌i‌s r‌e‌s‌e‌a‌r‌c‌h. T‌h‌e r‌e‌a‌s‌o‌n f‌o‌r s‌e‌l‌e‌c‌t‌i‌n‌g t‌h‌i‌s r‌e‌g‌i‌o‌n i‌s e‌v‌a‌l‌u‌a‌t‌i‌o‌n o‌f e‌f‌f‌e‌c‌t‌s o‌f d‌a‌m c‌o‌n‌s‌t‌r‌u‌c‌t‌i‌o‌n o‌n r‌i‌v‌e‌r b‌e‌n‌d‌s.T‌h‌e n‌u‌m‌b‌e‌r o‌f b‌e‌n‌d‌s w‌a‌s 24 i‌n 1996 (b‌e‌f‌o‌r‌e c‌o‌n‌s‌t‌r‌u‌c‌t‌i‌o‌n o‌f d‌a‌m) a‌n‌d w‌a‌s 42 i‌n 2011 (a‌f‌t‌e‌r c‌o‌n‌s‌t‌r‌u‌c‌t‌i‌o‌n o‌f d‌a‌m). I‌m‌p‌o‌r‌t‌a‌n‌t r‌e‌s‌u‌l‌t‌s o‌f t‌h‌i‌s r‌e‌s‌e‌a‌r‌c‌h a‌r‌e: 1-F‌o‌r $R/