Damage localization by wavelet analysis of uniform load surface

This paper presents a new technique for identifying damages in beam-type structures based on wavelet analysis of uniform load surface (ULS). Having come into focus in the field of damage detection, wavelet analysis revealed itself as a practical and state-of-the-art signal processing method for discerning abnormalities of mode shapes of structures, where the irregularities are considered as the indications of cracks. ULS is beneficial in terms of participating lower mode shapes and better immunity to noise. Continuous wavelet transform (CWT) is employed to analyze the ULS in order to find the damage site. The proposed method does not require any prior knowledge of the structure and combines the synergistic advantages of ULS technique and CWT to provide more accurate results in the face of high signal to noise ratio. A numerical study is conducted and three kinds of wavelets are utilized to evaluate the technique, namely symmetrical 4, Gaussian 4 and bior 6.8. The procedure is also experimentally investigated using a free-free beam structure

Modal behaviour of vertical axis wind turbine comprising prestressed rotor blades: a finite element analysis

Pre-stressing is a concept used in many engineering structures. In this study prestressing in the form of axial compression stress is proposed in the blade structure of H-Darrieus wind turbine. The study draws a structural comparison between reference and prestressed configurations of turbine rotor with respect to their dynamic vibrational response. Rotordynamics calculations provided by ANSYS Mechanical is used to investigate the effects of turbine rotation on the dynamic response of the system. Rotation speed ranging between 0 to 150 rad/s was examined to cover the whole operating range of commercial instances. The modal analysis ends up with first six mode shapes of both rotor configurations. As a result, the displacement of the proposed configurations reduced effectively. Apparent variations in Campbell diagrams of both cases indicate that prestressed configuration has its resonant frequencies far away from turbine operation speeds and thus remarkably higher safety factor against whirling and probable following failures

Using continuous wavelet transform of generalized flexibility matrix in damage identification

Generalized flexibility matrix method has recently been introduced for identifying damages with the aim of overcoming some shortcomings of the approaches based on flexibility matrix. Researchers that use flexibility matrix to detect damages in structures face truncation errors ensue from cut off higher-order mode shapes, which are difficult to measure in practice. In this paper, a new procedure is presented to detect the damage site in a beam-type structure, where generalized flexibility matrix in conjunction with continuous wavelet transform (CWT) is utilized. Since flaws and cracks cause changes in flexibility of a system, this characteristic can be used as a damage indicator. Gaussian wavelet transform with four vanishing moments as a signal processing method is implemented to find the irregularity in a vector obtained from generalized flexibility matrix which is considered as a sign of damage. This method does not need to have either prior knowledge about the intact structure or its finite element model. The proposed technique is evaluated by numerical and experimental case studies

Отношение членов реанимационной бригады и сопровождающих пациента лиц к присутствию родственников пациента первой степени родства во время сердечно-легочной реанимации в отделениях неотложной помощи

The presence of the patient’s family at their bedside during cardiopulmonary resuscitation (CPR) is one of the challenging issues that has been frequently taken into consideration. Considering the importance of this topic. The objective of the present study was conducted to determine the attitude of the CPR team members and the patient’s companions toward the presence of the patient’s first-degree relatives during CPR.Materials and methods. The descriptive-analytical cross-sectional study was conducted on 100 CPR team members of two University Hospitals and 120 near relatives of patients undergoing CPR in 2021. The data were collected by the researcher-made questionnaire and depression, anxiety, stress scale (DASS) during CPR. The collected data were analyzed by SPSS (version 22) statistical software.Results. From the perspective of both the CPR team members and the patient’s companions, the highest mean response was related to the fact that it would be better for the patient to agree on the presence or absence of their family before hospitalization and whether they have favorable conditions. The attitude toward the presence of the patient’s family during CPR was statistically significantly associated with the companions’ gender (p < 0.05) and with the experience of work and participation in CPR of the CPR team members (p < 0.05).Conclusion. Taking into account the different opinions of the CPR team members and the patient’s relatives about the presence of family during resuscitation, additional studies with a large sample size should be carried out.Присутствие семьи пациента у его постели во время проведения сердечно-легочной реанимации (СЛР) является одним из вопросов, привлекающих внимание. Настоящее исследование было проведено с целью определения отношения членов реанимационной бригады и сопровождающих пациента лиц к присутствию родственников пациента первой степени родства во время проведения СЛР.Материалы и методы. Описательно-аналитическое перекрестное исследование проведено в 2 университетских больницах с участием 100 членов команд, проводящих СЛР, и 120 близких родственников пациентов, которым проводили СЛР в 2021 г. Данные были собраны с помощью разработанного исследователем опросника и шкалы стресса, тревоги и депрессии (DASS) во время СЛР. Собранные данные были проанализированы с помощью статистического программного обеспечения SPSS (версия 22).Результаты. С точки зрения как членов команды, проводящей СЛР, так и близких пациента, наиболее значимым был вопрос о том, что самому пациенту было бы лучше договориться о присутствии или отсутствии своей семьи еще до момента госпитализации и выяснить, насколько для этого созданы благоприятные условия. Отношение к присутствию семьи пациента во время СЛР было статистически значимо связано с полом сопровождающего (р < 0,05) и с опытом работы и участия в СЛР членов реанимационной бригады (р < 0,05).Вывод. Учитывая различные мнения членов команды, проводящей СЛР, и близких пациента относительно присутствия семьи во время реанимации, следует провести дополнительные исследования с большим объемом выборки

Effect of different dietary protein levels and water salinities on biochemical heamolymph parameters of white leg shrimp (Litopenaeus vannamei) juvenile

In this study, biochemical heamolymph parameters indices of the white leg shrimp (Litopenaeus vannamei) with three dietry protein levels (25, 35 and 45%) in the three levels of water salinity(0-3, 12-15 and 32-35 ppt) was studied. For experimental 350 shrimps with the average weight of 5.55±0.18 g and length of 8.81±0.15 cm were distributed randomly in 27 ten tones (length: 600 cm, width: 170 cm and height: 100 cm) concrete tanks. Experimental group were fed to satiation 4 times a day the experimental period. The results showed that at dietary protein levels of 35 and 45% and the water salinity of 32-35 ppt the amount of protein, urea, HDL and LDL increased (p≤ 0/05). Cholesterol and triglycerides levels in treatment with dietry protein level of 45% and the salinity of 32-35 ppt had increased. The glucose level of the plasma changed only by the modification of the protein level and had a revers relation with this variable (p≤ 0/05). However, different levels of protein and salinity had no effect on the amount of hemolymph uric acid. So besed biochemical heamolymph parameters on the results of this study, in dietry protein level 35% and salinity of 32-35 ppt and at least stress in the levels

Job Stress and Work Ability Among Emergency Nurses in Isfahan, Iran

Background: Job stress is one of the most common health problems with clinical and psychological consequences, which can affect work ability among emergency nurses. Nevertheless, more studies are needed to shed light on the status of this disorder and its relevance to work ability in nurses in the emergency departments (EDs). Objectives: The current study aimed to determine job stress among emergency nurses and its association with work ability. Methods: This cross-sectional study was conducted in 2013 in hospitals affiliated to Isfahan University of Medical Sciences, Isfahan, Iran. Two hundred nurses who worked in the EDs were asked to complete a demographic questionnaire and special scales to assess their job stress and work ability. T-tests, analysis of variance, Pearson correlation coefficient and linear regression were used to analyze the data. Results: The mean job stress and work ability scores were 151.09 ± 0.01 and 26.9 ± 8.2, respectively. Fifty-five percent of the subjects had high job stress and fifty-seven percent showed low work ability. A significant indirect correlation was found between job stress and work ability scores in the subjects (P = 0.015). Conclusions: Nurses working in the EDs experience a high level of job stress and low work ability. This may decrease the quality of care and patients’ safety. Fulfilling the staff shortage in ED and improving management behaviors are important in this regard

Alterations in reproductive hormones during heat stress in dairy cattle

In dairy cows inseminated during the hot months of the year, there is a decrease in fertility. Different factors contribute to this situation; the most important are a consequence of increased temperature and humidity that result in a decreased expression of overt estrus and a reduction in appetite and dry matter intake. Heat stress reduces the degree of dominance of the selected follicle and this can be seen as reduced steroidogenic capacity of its theca and granulosa cells and a fall in blood estradiol concentrations. Plasma progesterone levels can be increased or decreased depending on whether the heat stress is acute or chronic, and on the metabolic state of the animal. These endocrine changes reduce follicular activity and alter the ovulatory mechanism, leading to a decrease in oocyte and embryo quality. The uterine environment is also modified, reducing the likelihood of embryo implantation. Systems activated by heat stress can influence reproduction at the hypothalamus, pituitary gland or gonads. However, the major impact is thought to be within the brain or at the pituitary gland. Measurement of plasma concentrations of the gonadotrophins provides a good indication of the effects at these higher levels, since the pulsatile secretion of luteinizing hormone (LH) is a reflection of the secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus. Both the secretion and actions of GnRH are influenced by the feedback actions of gonadal sex steroids and inhibin. Recent studies suggest that the use of gonadotropins to induce follicular development and ovulation can decrease the severity of seasonal postpartum infertility in dairy cows.Key words: Reproductive hormones, dairy cow and heat stress

Widespread occurrence of Tomato ring spot virus in deciduous fruit trees in Iran

Despite a long tradition of fruit-tree growing in all provinces of Iran, information on tree viruses in this country is scant. In the present study, presence of Tomato ring spot virus (ToRSV) was surveyed in various woody plants in this country by mechanical inoculation to herbaceous hosts, ELISA using a commercial antiserum, and PCR with specific primers. ToRSV was identified in the following plant-symptom combinations: Walnut with mottling, deformation, necrosis, and yellowing of main veins from Tehran Province; plum with yellowing of main veins, peach with yellowing of major veins and marginal necrosis, and hazelnut with interveinal chlorosis and marginal necrosis from Ardabil Province; apple with yellowing of main veins, mosaic and necrotic lesions, quince with large necrotic spots, and almond with leaf deformation and rosetting from Khorasan Province; and raspberry with marginal necrosis of leaf and necrotic lesions from Mazandaran Province. Mechanical inoculation from walnut, plum, peach, hazelnut, apple, quince, almond, and raspberry to Nicotiana tabacum cv. Samsun resulted in systemic infection. The virus isolates induced local lesions, leaf deformation, and necrosis in N. rustica, chlorotic local lesions on Chenopodium quinoa, and large local lesions on Gomphrena globosa. All samples were ELISA positive. PCR with specific primers resulted in the amplification of the expected fragment (490 bp). This study shows extensive occurrence of ToRSV in Iran.Keywords: Tomato ringspot virus, fruit tree viruses, Ira