the effect of residual stress on fatigue behavior of v notched components a review

Abstract: Fatigue strength of mechanical components in the high cycle regime depends on the intensity of the residual stress field induced by non-homogeneous plastic deformation or the solidification of a local portion of material due to welding operations. In presence of geometric variations modelled as sharp V-notch angle, the residual stress distribution near the notch tip is singular and follows the same solution obtained by Williams in 1952 where the intensity of the asymptotic stress field is quantified by the notch stress intensity factor (NSIF). However, the residual stress varies during fatigue loading until a stationary value is reached. Numerical models were developed for the calculation of the residual NSIFs and their variation under fatigue loading. Taking advantage from these models, new approaches were recently developed which are able to predict the fatigue strength of pre-stressed notched components. A review of such recent advances is described in this work

Comparison of chilling and heat requirement in some peach and apricot cultivars

Bud Dormancy in deciduous fruit trees of the temperate zones is a phase ofdevelopment that occurs annually and enables trees to survive cold winters. Chilling andheat requirements for breaking dormancy and flowering were studied in five peach (Kosary,Haj Kazemi, Anjiry Asali, Anjiry Zafarany, and Zoud Ras) and four apricot (asgarabad,shamlo, shakarpare, tabarze ghermez) cultivars. Various models (two chilling hour models,the <7C and 0-7C models, and two chilling unit models, the Utah and Low Chill) were usedto measure the accumulation of chilling requirement. The heat requirements were calculatedas the growing degree hours (GDH) accumulated from breaking of dormancy to the F50 (50%of opened flowers). The cultivars studied showed a range of chilling requirements (chillunits, CU), between 746 to 868 CU for peach and 652-826 CU for apricot. The heatrequirements for peaches and apricots were between (4099 to 4543GDH) and (2987 to3465GDH) respectively. Apricot cultivars with lower chilling and heat requirements showedearlier flowering dates. Thus apricot cultivars bloomed between 15 and 16 day before peachcultivars and Heat requirements were found to be more important for regulation offlowering time than were chilling requirement in our climatic condition

Experimental and numerical investigations of fracture behavior of magnetostrictive materials

Abstract: The purpose of this work is the characterization of the fracture behaviour of giant magnetostrictive materials subjected to a magnetic field. Both experimental and numerical investigations have been performed, focusing on iron and rare earth alloys, such as the commercially named Terfenol-D. Tests have been carried out on single-edge precracked specimens subjected to three-point bending in the presence of magnetic fields of various intensities and fracture loads have been measured at different loading rates. Recent studies on local stress fields in proximity of crack and notch tips have shown that Strain Energy Density (SED), averaged in a circular control volume which includes a crack tip, could be a robust parameter in the assessment of brittle fracture resistance of several materials. Coupled-field analyses have then been performed on both plane stress and plane strain finite element models and the effect of the magnetic field on fracture resistance of Terfenol-D alloy was predicted in terms of averaged SED. A relationship between the SED's control volume size and the loading rate has also been proposed

Screening and evaluation of indigenous bacteria from the Persian Gulf as a probiotic and biocontrol agent against Vibrio harveyi in Litopenaeus vannamei post larvae

Isolation of autochthonous bacteria from marine sources as a potential probiont in biocontrolling against pathogenic Vibrio species in the shrimp culture industry was the aim of current research. A total of 198 bacterial strains were isolated from pond water, sediment, hepatopancreas and gut samples of shrimps after culturing the samples on Tryptic Soy Agar and incubated at 30 °C for 24-48 h. The isolates were tested for their antagonistic activity in contact with Vibrio harveyi. Two strains (IS02 and IS03) that isolated from the gut and pond sediment were showed antagonistic against V. harveyi. According to 16S ribosomal DNA gene sequence analysis, the strain IS02 was identified as Bacillus subtilis and IS03 as B. vallismortis. Further, the two bacterial species, B. subtilis and B. vallismortis were challenged separately for probiotic activity in the post larvae of Litopenaeus vannamei against pathogenic V. harveyi. The present study identified B. subtilis IS02 and B. vallismortis IS03 had biocontrol activity against V. harveyi in vitro and in vivo and they increase growth performance of L. vannamei in post larvae stage

Isolation, identification and characterization of new luminous bacteria from Chah Bahar Port, southern marine habitat of Iran

Coastal region of Chah Bahar port, Sea of Oman, was screened for the presence of bioluminescence bacteria for the first time. Water samples were taken from surface and subsurface layers and immediately spread on nutrient seawater complete (SWC) agar. Luminous colonies were observed after an overnight incubation at 25°C. Among twenty luminous isolates, four of them were selected for preliminary bacterial identification based on morphological and physiological characteristics. 16S rRNA genes of selected bacteria were then sequenced in order to be submitted in GenBank database as new strains and performing phylogenetic analysis. Four different submitted bacterial strains are as follow, Vibrio sp. Persian 1, Vibrio sp. Persian 2, Vibrio sp. Persian 3, and Vibrio sp. Persian 4 with accession numbers of KC505639, KC765088, KC765089, and KC896417, respectively. Light emission of isolated luminous bacteria was measured using luminometer. Vibrio sp. Persian 1 was found as the best light emitter with counts per second/OD 600 nm equal to 10 × 10^6 RLU/Sec/OD. Isolated Vibrio species were tested for their ability to form biofilm. Vibrio sp. Persian 3 showed weak ability to produce biofilm while other species were considered as moderate biofilm producers

Comprehension of complex sentences in the Persian-speaking patients with aphasia

Introduction: To study sentence comprehension in Persian-speaking Patients with Aphasia considering the factors of complexity. Methods: In this cross-sectional study, the performance of 6 non-fluent aphasic patients were tested and their performance was compared to 15 matched control group. Comprehension of semantically reversible sentences was assessed using a binary sentence-picture matching task. The stimuli were as follows: clefts; subject clefts and object clefts, also relative clauses; subject relatives and object relatives. All of them were types of movement-derived structures and also simple declarative sentences as the control task. Results: The best performance of aphasic patients were seen in the comprehension of subject clefts, although prior to this result we assumed that simple declarative sentences (in which there is no structural factor of complexity) can be understood easily. They showed the highest difficulty in the comprehension of object relatives. Furthermore, the performance of patients in the comprehension of relative clauses was significantly weaker than understanding the clefts. Conclusion: The outcomes of this study suggest that the sentence comprehension deficits of aphasic patients, in contrast to the specific deficit models, may not be related to linguistic disabilities. Moreover, the problems in the comprehension of non-canonical sentences may be related to failure in the allocation of attention. Finally, our results support the claims that neural characterization of the cognitive resources (e.g. working memory) is disrupted in sentence comprehension deficits. © 2019 Iran University of Medical Sciences. All rights reserved

The data set development for the National Spinal Cord Injury Registry of Iran (NSCIR-IR): progress toward improving the quality of care

STUDY DESIGN: Descriptive study. OBJECTIVES: The aim of this manuscript is to describe the development process of the data set for the National Spinal Cord Injury Registry of Iran (NSCIR-IR). SETTING: SCI community in Iran. METHODS: The NSCIR-IR data set was developed in 8 months, from March 2015 to October 2015. An expert panel of 14 members was formed. After a review of data sets of similar registries in developed countries, the selection and modification of the basic framework were performed over 16 meetings, based on the objectives and feasibility of the registry. RESULTS: The final version of the data set was composed of 376 data elements including sociodemographic, hospital admission, injury incidence, prehospital procedures, emergency department visit, medical history, vertebral injury, spinal cord injury details, interventions, complications, and discharge data. It also includes 163 components of the International Standards for the Neurologic Classification of Spinal Cord Injury (ISNCSCI) and 65 data elements related to quality of life, pressure ulcers, pain, and spasticity. CONCLUSION: The NSCIR-IR data set was developed in order to meet the quality improvement objectives of the registry. The process was centered around choosing the data elements assessing care provided to individuals in the acute and chronic phases of SCI in hospital settings. The International Spinal Cord Injury Data Set was selected as a basic framework, helped by comparison with data from other countries. Expert panel modifications facilitated the implementation of the registry process with the current clinical workflow in hospitals