فهرست مطالب dariush jalili

Real-time hybrid simulation (RTHS) is a form of testing where the physical component of structure communicate with numerical model which simulates the behavior of the rest of the structure. Interface forces between the experimental and computational substructure are imposed by an actuator. The resulting displacement and velocity of the experimental substructure are fed back to the computational engine to determine the interface forces applied to the computational and experimental substructures for the next time step. In this paper, the RTHS technique is used to conduct experiments with a numerically simulated structure and physically tested tuned liquid damper (TLD). One very important factor which causes instability in RTHS is the actuator's inability to perform the commands from the simulator in real-time. In RTHS, an actuator dynamic is approximated by a pure time-delay, and the time-delay in the closed loop system causes inaccuracy results or even instability. Therefore, Delayed Differential Equation (DDE) is used to determine the critical time-delays depending on the TLD parameters. Then, the compound stability condition is investigated for a general case and the results show that the mass ratio has a lower limit for low delays and upper limit for high delays to remain stable. As frequency and amplitude ratios increase, the margin of stability for the mass ratio increases.

Nowadays, issues related to soil erosion are one of the most critical issues and one of the major concerns in watershed management. Accordingly, knowledge on soil erosion process at watershed scale needs proper, suitable, accurate, and desirable temporal resolution data collection using appropriate device. An innovative device is designed and manufactured through this research for automatic sampling and measuring suspended sediment concentration. This aimed at a better understanding of the processes of soil erosion and sediment yield through better time-distributed measurements. The background of studies and research related to the project has been reviewed worldwide and based on previous experiences, manufacturing the mechanical part of the system was carried out and completed. Also, the necessary laboratory practices for designing, formulating, and simulating the electronic parts were performed. Numerous tests and attempts were made to optimize the mechanical and opto-electronic parts based on determining different arrangements and sources of light. The field test of the device in several rivers in the northern Iran indicated a high agreement of more than 93.25% between the observed and estimated suspended sediment concentrations. The designed sampler is expected to provide suitable estimates on concentration of suspended sediment in the dominant range in watercourses with acceptable, affordable cost and energy, particularly in special conditions such as floods, in the entire day and night hours, and even for remote areas.

Soil improvement is an appropriate option that is often the most economical method to solve the geotechnical problems. When due to the results of geotechnical studies, the need for soil improvement to improve the soil loading, and to reduce the soil subsidence against the applied loads is detected, the required measures should be taken to prevent the destruction caused by the mentioned factors. One of the common methods for soil improvement is compression by the roller. In this study, the effect of the interaction of soil and momentum caused by the impact roller was evaluated. The results showed that by increasing the roller impact momentum, the ascending changes of the improved depth would also reduce and tend to a constant value. Also, increased coefficient of friction up to 22% can increase the soil improved depth.

Cleft lip and cleft palate are one of the most frequent congenital anomalies worldwide. This study was conducted in order to measure the frequency of cleft lip and palate among live births in Akbar Abadi Hospital. This is a descriptive study, dealing with 57526 cases of live birth out of 59477 medical files in Akbar Abadi Hospital from 2004 to 2008. All the collected data were recorded in specific data sheets. The frequency of cleft lip or palate or both was 103 cases in 57526 live births, which is 1.79 per 1000 live births. The frequency of cleft lip, cleft palate and concurrent cleft lip and palate were 0.53, 0.33 and 0.92 per 1000 live births respectively. Among the newborns with any type of this anomaly, 53 (51.5%) were males and 50 (48.5%) were females. Twenty nine neonates (28.2%) had limb anomalies, 13 (12.6%) had syndromic features, 4 (3.9%) had limb anomalies and syndromic features, and 3 (2.9%) had cardiovascular anomalies. Our study indicates a frequency of cleft lip and/or palate near to the average international figure, and close to the findings in European and East Asian countries. Furthermore, the frequency of cleft lip and palate in our study was different from American countries and India probably due to ethnic differences.