Showing 62 results for Hamidi
Volume 1, Issue 2 (winter 2018)
Abstract
Dispersion type of layered clay plated in aqueous media creates different structures and affects the final properties of its suspension. On the other hand, the presence of different electrolytes in some industrial applications affects the stability of clay suspensions. Considering the application of clay nanoparticles in various industries and the importance of this subject, in this research, the effect of preparation method, nanoparticle concentration, type and ionic strength of electrolytic medium and time elapsed on the stability behavior of laponite nanoparticles suspensions were studied. The results showed that preparing of the suspensions indirectly, results in more stable samples. It was observed that with increasing of sodium chloride concentration, the repulsion between the clay plates decreased and the phase separation and instability of the suspensions increased at higher NaCl concentrations. Furthermore, it was seen that in all electrolyte media, gel-like structure develop with increasing of nanoparticle concentration. In presence of bi-valance CaCl2 salt, most of suspensions were unstable and have two phases and increasing of this salt concentration had not significant effect on their stability. In electrolyte media containing mono- and bi- valance salts (studied in this research), concentration of calcium cation determines the type of stability behavior of laponite nanoparticles suspensions.
Volume 1, Issue 4 (12-2012)
Abstract
The purpose of this study is Understanding status and relationship between empowerment and contextual performance with job satisfaction of employees of Islamic Azad University Dezful Branch. Empowerment based on Bowen and Lawler of model (1992), contextual performance based on Van Scotter and Motowidlow of model (1994) and job satisfication based on universal model of single question measured. Proportion with purpose of study, two main hypothesizes and ten secondary hypothesizes codified. Statistical social of this study was 355 personals of this university branch. Tools used in this study to collect data was questionnaire. This questionnaire has three sections that one section is job satisfication based on universal model of single question, second section is empowerment based on Bowen and Lawler of model (1992) in four dimensions which includes information sharing, trust, training and reward and third section is contextual performance based on Van Scotter and Motowidlow of model (1994), which includes two dimensions of facilitation of interpersonal relationships and dedication work. The Cronbach's alpha reliability coefficient was approved by them. Meaningful relationship and coefficient correlation between empowerment and performance and each dimensions of their with job satisfication were investigated. Then structural equation model was used to test the theoretical model and the direct and indirect effects of these factors on job satisfaction of employees were found. Results of tests impress that each of components empowerment and contextual performance with job satisfication have meaningful relationship and had seen among of dimensions of their only training with job satisfication has not meaningful relationship.
Volume 2, Issue 6 (Summer 2021)
Abstract
The present study aimed to prioritize the factors of cultural development of sports in the country from the perspective of experts. This applied research was a descriptive survey conducted by a mixed (quantitative-qualitative) method. The statistical population is in the qualitative section, staff managers, professors of sports management and university researcher who have related research work. Sampling in the qualitative part was done in the form of snowballs until the theoretical saturation was reached with experts. In the quantitative part, the samples were composed of managers and sports specialists, university professors with teaching experience in the socio-cultural field of sports, and researchers who had conducted research studies in this field 49 researcher-made questionnaires were Targeted and distributed online and in the field. In order to analyze the data, descriptive statistics were used for demographic characteristics, and inferential statistics were used by Expert choice statistical analysis software version 11 to weigh and prioritize the factors of cultural development of the sport. The results showed that the factors of cultural development of sports in the country are family priority and educational sports (0.408), responsibility and moral conscience (0.273), avoidance of moral vices in sports (0.173), and cultural customs in sports, respectively. (0.080), and cultural communications and exchanges (0.043) and cultural activities in sports (0.022). In general, it can be said that the spread of culture in the family and educational sports can directly reduce the root of moral and behavioral disorders.
Volume 3, Issue 1 (12-2003)
Abstract
An important task in the initial design stages of rapid-transit type systems or "metros" is the allocation of signals and control points. These are placed so as to achieve a specified minimum time-separation between trains (headway), whilst minimizing the amount of signaling equipment but maintaining the highest level of safety. Conventional signaling and control systems are based on the fixed-block principle, whereby the track (or guide way) is divided into sections of predetermined length. A train is only allowed to proceed into a block when that block and usually the next one is clear of traffic. With the moving-block concept, a train can follow a preceding train at a safe braking distance behind the tail of the train.
In this paper, the transient performances of the two signaling systems are compared. A multi-train simulator which was originally developed at Birmingham University (U.K.) with a fixed-block algorithm, has been adopted and modified to accommodate the moving block algorithm. Both signaling systems were applied to Singapore Mass Transit Railway (MTR) and the results were compared in terms of train movement and transient performances including headway and station delay under safety and speed restrictions. Results have shown that with a pure moving-block system a considerable improvement in transient performance can be achieved.
Volume 3, Issue 1 (12-2003)
Abstract
In this paper, behavior of teleoperation systems with modeling error and delay time error in Smith predictor is discussed. In teleoperation systems, modeling error is inevitable. This paper discusses stability of teleoperation systems with modeling error. First, error of delay time in teleoperation systems by using of Internet as communication channel is considered and the performance of Smith predictor in teleoperation systems with delay time error is discussed. Next, a new structure for teleoperation system is proposed. An adaptive filter is integrated into the new structure for determination of delay time in communication channel. The new structure augments wave variables and Smith predictor to provide an effective method for teleoperation systems. Along with the adaptive filter, this new structure is shown to overcome instability due to the variability of the delay times. Simulations results show significant improvements in the system performance.
Volume 3, Issue 4 (12-2017)
Abstract
Background: Enterobious vermicularis (E. vermicularis) is one the most common parasitic infection among children.
Objectives: The present study aimed to determine the prevalence rate of enterobiasis among preschool children in Mazandaran province, northern Iran.
Materials and Methods: In this cross–sectional study, 653 preschool children were recruited via the cluster sampling method during April 2013 to Feb 2014. A questionnaire was administrated to parents by an interviewer and determined children’s socio-demographic characteristics, personal hygiene, and healthy behaviors. The Graham technique was applied for diagnosis. Data were analyzed using logistic regression model and chi-square test.
Results: In a total of 653 examined subjects, the prevalence rate of E. vermicularis was 19.4%, among which 40.9% were male, and 59.1% were female. The highest and lowest prevalence rates of E. vermicularis were found in Neka (61.4%) and Tonekabon (1.6%) districts, respectively. A significant association was found between infection and residency, parental occupations, parental education, number of family members, changing underwear, sterilization of linen clothing, taking daily bath, boiling or ironing clothes.
Conclusions: The high prevalence rate of E. vermicularis infection in this study proves the stability status of enterobiasis in this area, posing a risk for children there. Systematic control of infection in children is proposed.
Volume 4, Issue 1 (9-2004)
Abstract
In this paper, we try to use modeling based on singular perturbation theory, in order to control satellite attitude during the wide rolling angle maneuvering through nonlinear H∞ control strategy. Differential equations describing dynamics of the satellite are presented first, and by choosing the appropriate dynamic model for actuators and based on the standard singular perturbation model, the closed-loop system is created. Next, this model is put into the appropriate form to solve H∞ problem. Then, after solving the HJI equation, the control law is determined. Simulation results for a nominal satellite control based on our approach are finally presented.
Volume 4, Issue 4 (Fall 2018)
Abstract
Aims: The aim of this study was species identification and analysis of species of Leishmania isolated from clinical samples.
Materials & Methods: The samples were collected from patients that were infected from different parts of Iran. After microscopic examination, we used PCR method for the ITS1 (internal transcribed spacer 1) RFLP method (digestion with and for phylogenetic construction, DNA sequencing of
Findings: Two samples from Khorasan province (Mashhad) were Leishmania (L. ), while others were Leishmania major (L. ). L. more variable compared with L. . The molecular sequencing differences between L. to geographical distribution. Based on the results of PCR product in the gel electrophoresis and DNA sequencing for L. L. , the DNA sizes were between 350 and 369bp. The RFLP for L. L. and one respectively. The sequences all samples from central parts are the same, but there is difference with the samples isolated from of Iran.
Conclusion: The sequences of of Leishmania major separated from Damghan and Esfarayen are different from other samples. Similarity of DNA sequences of North-East part of Iran of L. from central parts was 99%. The similarity of two isolates of L. 96%. The most similarity of Leishmania isolated was 95% with Indian isolate and the most similarity for Leishmania major was 99% with Friedlin strain.
Volume 7, Issue 4 (Fall 2019)
Abstract
Aims: Test anxiety is a significant and scary distressing feeling that appears before, during, or even after the exam.
The current study aimed to predict test anxiety in high school female students based on their spiritual well-being and mindfulness.
Materials & Methods: In this descriptive-analytic and cross-sectional study, the statistical population included all 4
th grade of girl high school students in Tehran (140,000 students). The sample concluded 312 female students of 4
th grade high schools in Tehran selected by multistage cluster sampling. The test anxiety scale developed (2004), Langer's Mindfulness scale (2004), and Well-Being scale (Paloutzian and Ellison; 1982) were completed by participants. Data was analyzed using Pearson correlation test, Enter multiple and stepwise regression.
Findings: Pearson correlation showed a significant and negative relationship between test anxiety and spiritual well-being variables (r=-0.28
; p=0.05) and also the negative relationship with mindfulness (r=-0.44; p=0.05). Regarding the results, students' test anxiety was predictable based on their spiritual well-being and mindfulness and both variables can predict 9% of the variances of changes in the test anxiety (R
2=0.09).
Conclusion: According to the results, the higher level of spiritual well-being and mindfulness, the lower level of test anxiety will be observed in students. So, it is expected that by focusing on specific techniques of mindfulness and performing activities that have a positive impact on students' spiritual well-being can reduce the level of student anxiety and, consequently, improve their academic performance.
Volume 8, Issue 1 (Winter 2020)
Abstract
Aims: One of the most common childhood disorders that cause many problems during school years is Attention Deficit Hyperactivity Disorder (ADHD). This disorder requires counseling and treatment. Therefore, the aim of this study was to determine the effect of parents’ cognitive-behavioral group counseling on learning problems and anxiety of hyperactive children in primary school.
Materials & Methods: This experimental study with pretest-posttest design with control group was conducted on 60 parents of 7 to 13-year children who were referred to Counseling Center of Education Department of Ramhormoz, Khuzestan, Iran in 2017-2018 academic year. The subjects were selected by purposive sampling method and randomly assigned into two experimental (n=30) and control (N=30) groups. The ADHD of their children was assessed using Conner’s Parents Rating Scale. In experimental group, 9 sessions of cognitive-behavioral group counseling were conducted; however, the control group did not receive the intervention. After the sessions, hyperactivity of children in both groups was evaluated with the Conner’s Parent Parents Rating Scale. Data were analyzed by SPSS 21 using multivariate analysis of covariance (MANCOVA) and univariate analysis of covariance.
Findings: By controlling the pretest effect, a significant difference was observed between the experimental and control groups in terms of learning problems (F=177.94; p<0.001) and symptoms of anxiety (F=279.56; p<0.001).
Conclusion: Cognitive-behavioral group counseling for parents can reduce the symptoms of ADHD children in primary schools.
Volume 8, Issue 2 (Spring 2020)
Abstract
Aims: The purpose of the present study was to identify the effectiveness of computer games interventions in improving attention and working memory of children with attention deficit hyperactivity disorder.
Participants & Methods: This semi-experimental study was pre-test/post-test with the control group and the statistical population was the second to sixth grade students in Najafabad City in the academic year of 2018-2019. Among them, 20 students were purposively selected based on diagnostic interview and screening score using Swanson et al. questionnaire and were randomly divided into two 10 experimental and control groups. Data were collected using SNAP-IV (Swanson, Nolan, and Pelham; 2001) questionnaire, Digit Span Backwards Task (Wechsler; 2008) and Corsi Block-Tapping Test (Corsi; 1972). Computer game interventions consisting of 20-minute in 18 sessions run just for the experimental group. Finally, data were analyzed using multivariate analysis of covariance.
Findings: Results showed that computer game interventions had a positive effect on improving spatial visual attention and working memory, but there was no significant effect on verbal memory (p<0.05). Also, 74% of the differences in the groups were due to the impact of the intervention (p<0.05).
Conclusion: According to the results, computer games as a cognitive intervention have been effective in increasing attention and spatial memory in children with attention deficit hyperactivity disorder. In addition, it is suggested that new methods such as computer games can be used to improve cognitive skills and reduce students' learning problems.
Volume 8, Issue 2 (Spring 2020)
Abstract
Aims: Having a child with autism spectrum disorder can put a lot of stress and pressure on parents and affect their quality of life, as compared to parents of normal children. In this regard, the present study aimed to identify and determine the effectiveness of group cognitive behavioral counseling of the parents of children with autism spectrum disorder on their communication interactions with children.
Participants & Methods: Population consisted of mothers of children with autism spectrum disorder in the city of Shiraz, of which 40 eligible volunteers were selected using purposeful sampling method and were randomly divided into two groups of 20 (control and experiment) in the academic year of 2018-2019. Data collected using the Child-Parent Relationship Scale (CPRS; Pianta). Having completed the questionnaires by the target population, the experiment group received the intervention training program of group cognitive behavioral counseling for 10 one-hour sessions. However, the control group received no intervention training. Multi-variate covariance analysis and SPSS 22 were used to analyze data. The significance level was considered as 0.01.
Findings: The group cognitive behavioral counseling for mothers of children with autism spectrum disorder was effective on communication interaction with children and improved it (p= 0.001). Regarding the assessed effect, it should be noted that the degree of changes, according to eta coefficient (effect rate) was 23.3%.
Conclusion: According to the findings, group cognitive behavioral intervention method can be effective on improving parenting for children with autism spectrum disorder.
Volume 8, Issue 3 (Summer 2020)
Abstract
Aims: This study was done to investigate the Effectiveness cognitive effect of visual and auditory memory on improving cognitive flexibility of children with Attention Deficit / Hyperactivity Disorder.
Participants & Methods: This study was a quasi-experimental one which was done by pretest-posttest with control group. The statistical population of this study was all students with Attention Deficit / Hyperactivity Disorder in Kermanshah in the academic year of 2018-2019. The sample consisted of 34 people who were selected by randomized sampling and replaced in two equal groups of experimental (17 subjects) and control group (17 subjects). The research tools were: SWAN Qquestionnaire and Stroop Color-word Test. Data was analyzed using mean and standard deviation of Levine test and homogeneity of slope from regression and covariance analysis for study the research hypotheses.
Findings: The results of this study showed that cognitive effect of visual and auditory memory could improve the cognitive flexibility with effect size 0.45 in children with Attention Deficit / Hyperactivity Disorder at the significant level (P<0.01)
Conclusion: It can be concluded that cognitive of visual and auditory memory training may enhance certain skills in ADHD children, but more research is required to generalize the positive effects of these programs to the other clinical features of ADHD.
Volume 8, Issue 4 (Fall 2020)
Abstract
Aims: Adolescents who have been deprived of family support for various reasons are more likely to be in vulnerable groups in society, resulting in more risky behaviors. This study aimed to determine the effectiveness of psycho-drama in reducing high-risk behaviors in unsupervised adolescent boys.
Materials & Methods:
This study was a quasi-experimental pretest-posttest design with a control group. The statistical population consisted of unsupervised teenage boys between the ages of 12-13, who were studying in the sixth grade in Zanjan in the 2018-2019 academic year. 40 students were selected by purposive sampling and substituted in two equal groups as experimental and control groups. The main tool was the Youth Risk Behavior Surveillance System (2013). Psychodrama intervention was performed for 9 sessions (each session 90 minutes) for the experimental group, but the control group received no intervention. At the final session, both experimental and control groups received a posttest. Data were analyzed using analysis of covariance by SPSS23.
Findings: Results showed a significant difference between the two groups in the posttest phase (p<0.05). Psychodrama decreased high-risk behaviors in the experimental group. The percentage of these changes based on the Eta-square was 41.3%. Also, according to the results, Eta-square of components was 37% for the smoking, 32% for the alcohol; 17.9% for the psychotropic; 36.3% for aggressive behaviors,35.3% for thinking and committing suicide, 30.5% for escape component, and 35.5% for relationship the opposite sex (p<0.05).
Conclusion: According to the findings, it can be concluded that psychodrama is an effective adjunctive therapy to reduce the symptoms of high-risk behaviors of unsupervised adolescent boys, and it is recommended to counselors in preventing psychological damage in schools.
Volume 9, Issue 1 (12-2009)
Abstract
In this paper linear aeroelastic analysis of a swept wing with two degrees of freedom in an incompressible flow is investigated in time - domain. The equations of the motion of an elastic wing are derived from Lagrange’s equations in time - domain. The wing is modeled as a cantilever beam rigidly connected to the root. Considering assumed modes of cantilever beam, aerodynamic forces and moments acting on the wing are derived using strip - theory in an unsteady incompressible potential fluid flow. The governing aeroelastic equations of the system have been introduced in dimensionless form. These equations are solved via a numerical method. Comparisons between obtained results and both available experimental data and the results of some cited references indicate a close agreement.
Volume 9, Issue 1 (Winter 2021)
Abstract
Volume 9, Issue 3 (5-2020)
Abstract
Tomato bacterial wilt and canker caused by Clavibacter michiganensis subsp. michiganensis (Cmm) is an economically important seed-borne disease in the major tomato growing regions all over the world. Also, this disease is present in northern, northwestern, and central provinces of Iran. This study aimed to isolate fluorescent pseudomonads with efficient antagonistic activity against Cmm from tomato rhizosphere and rhizoplane. In the present study, ninety six fluorescent pseudomonads were isolated from rhizosphere and rhizoplane of tomato plants using King’s medium B agar and tested for antagonistic activity against Cmm by co-inoculation culture in vitro. Seed and roots of tomato transplants were inoculated with representative antagonistic strains and planted in the soil infected by Cmm in greenhouse. The incidence and severity of the disease were assessed on tomato as well as growth parameters. Nineteen strains exhibited inhibitory activity against Cmm in vitro and two selected strains (M1R1 and H1R1) were identified as Pseudomonas putida based on their phenotypic characteristics and partial 16S rRNA gene sequences. These two strains produced siderophore and hydrogen cyanide. In greenhouse, strain M1R1 reduced the disease incidence by 30% and 40% in Superluna and Falat cultivars, respectively. Strain H1R1 reduced the disease incidence by 20% only in Falat cultivar. Strains M1R1 and H1R1 decreased the disease severity by 52.93 % and 10.60 % in Superluna and 47.90 % and 42.88 % in Falat cultivars, respectively. Strain M1R1 increased the growth parameters, including fresh and dry weight, and height of the inoculated plants significantly in comparison with control. These results indicated that rhizospheric fluorescent pseudomonads could be effective agents in the biocontrol of tomato bacterial wilt and canker disease.
Volume 9, Issue 4 (3-2020)
Abstract
The main purpose of this study is to predict the behavior of employees according to perception of possible changes in their organizational resources. This research aims to discover the latent behavioral intentions which individuals showing in common, within an organizational ecosystem through an objective approach. Using sequential exploration strategy, the research was implemented through 5 main steps and research model has been verified by means of experimental and empirical methods. The ecosystem studied in this study, was Iranian state and semi-state banks, which were precisely studied in 416 subjects. Also, in order to obtain a model for predicting the organizational behavior of employees, at first, behavioral intentions were typologized by conservation of resources approach, and then modeled with fixed and random effects in form of mixed equations. Results showed that predictions of human behaviors at the ecological level of resources have great commonalities that can be identified by a resource-based approach. The results also showed that the behavioral intentions of employees in Iranian state and semi-state banks in threatenedsocial support is to be passive, andin the presence of positive or negative perceptual interaction from leader, this tendency could change from " being passive” to "trying to retain" in both cases. Identifying the boundary points of changing behavioral intentions and the distance of employees’“behavioral intention" from these points was another finding of this study that could be a guide for regulating effective interventions of leadersin the studied ecosystem.
Volume 10, Issue 3 (Summer 2019)
Abstract
The large biological networks increase computational complexity during the execution of the algorithm and create constraints for working with such networks. By preserving the behavior and output of the main network, complexity is reduced, and the process of obtaining results and analyzing the network is quickly accomplished. Using mathematical and computational tools to simplify the biology networks provides better results in various sciences, especially in applications of biological sciences. Boolean modelling and finding adsorbents in biological networks will make it easy to display and analyze. This study was carried out through Boolean modelling on the Abscise Acid signal transduction network. Abscise Acid is one of the most important and effective regulators in plant growth. Our method started from an initial state and according to the rules of updating, found network adsorbents. Our proposed method, in contrast to other methods, will be able to simultaneously detect the absorbing points while plotting the state transition graph. In this way, finding all the system adsorbents is guaranteed.
Volume 10, Issue 4 (12-2024)
Abstract
Iranian mosquitoes (Diptera: Culicidae) include 73 species across eight genera. The fauna of mosquitoes in Guilan Province comprises 34 species classified into seven genera. A faunistic study of mosquitoes was conducted with emphasis on an aggressive biter mosquito reported by local people in Anzali and Rasht Cities of Guilan Province, northern Iran. Collections were made by hand catches using manual aspirators, light traps, BG lure traps and ovitraps during August–November 2023 in all 17 counties of the province. Species identification was carried out using morphological keys and molecular analysis of the barcode region of the cytochrome c oxidase subunit I (COI) gene. In total, 29 larvae and 896 adult specimens were collected which were not recognized as a species previously known to occur in the province. The aggressive biter mosquito was morphologically identified as Aedes albopictus (Skuse, 1895). The sequences of the barcode region of the COI gene of the species were generated for the first time in the country. This species was collected in 14 counties of the province. Thus, the mosquito fauna of Guilan Province increased to 35 species.
