Health monitoring allows small failures and damages to be identified and fixed before they turn into major and irreparable damages, to prevent loss of life and to make it possible to reinforce or improve it at the lowest cost. Currently, in the field of civil engineering, the health monitoring of structures is done in sensitive structures. One of the parts of the structure that may suffer initial damage before loading and during implementation due to difficulty in implementation is Concrete Filled Tube (CFT)columns.  One of the most likely damages in CFT columns is interface debonding damage. This damage causes the column to become weak and not benefit from the characteristics of steel and concrete together. Accordingly, in the present study, this damage and its severity in seismic (dynamic) parameters have been investigated. The results of the study show that damage causes changes in the mode shape of the structure, and it has caused a 6.38% reduction in the frequency in the first (main) mode of the structure. Also, the damping of the damaged specimen is reduced by approximately 12% compared to the healthy specimen. On the other hand, the results show that the severity of damage is very effective in changing seismic parameters. So that by doubling the damage area, the frequency decreased by approximately 0.35% and reached from 873.27 Hz to 20.870.20 Hz, but the mode shape of damage did not affect the frequency

The present article investigates effects of the multi-frequency excitation on the output power of a piezomagnetoelastic energy harvester. The piezomagnetoelastic power generator is assumed to operate in the mono-stable mode. A perturbation technique based on the method of multiple scales is employed to develop an analytical solution to nonlinear differential equations governing the system dynamics. In addition, a Runge-Kutta numerical scheme is used to solve the differential equations. It is shown that the perturbation solution is in a close agreement with the numerical solution. The system response is determined for several cases including super-harmonic, combination and simultaneous resonances. The steady-state output voltage is then obtained for each case and compared with that of a single-frequency excitation. Due to nonlinearities present in the system, a multi-frequency excitation gives rise to complicated phenomena such as combination and simultaneous resonances. It is found out that exploiting these resonances can significantly increase the amount of energy harvested.

Introduction: Usually osseointegration takes between three to six months after implant placement but patients are interested to have early loading. There are no definitive criteria for measuring bone mineral density (BMD), insertion torque (IT) (final torque force) and resonance frequency analysis (RFA) (primary implant stability) to determine exact loading time based on the relationship between the above-mentioned parameters. The aim of this study was to determine the relationship between IT, RFA and BMD in screw-type implants.Materials and Methods: This clinical trial was conducted on 18 patients who were candidates for ITI implant placement. Written consent was taken and jaw bone density was determined via a digital radiography technique before surgery. After implant placement, RFA and IT were measured. Fifty-five ITI implants of the total 62 implants placed were evaluated; the implants were 12 mm long with a diameter of 4.1 mm. Data was analyzed with Pearson’s test using SPSS.15 software (a=0.05).Results: There was a significant relationship between IT, RFA and BMD. Pearson’s test showed a correlation coefficient of 0.872 to 0.789 between the three parameters, indicating a strong relationship between them. The mean bone density was 1.468±0.042 g/cm2; the mean RFA was 66.01±2.2 ISQ and the mean IT was 34.62±3.33 N/cm2.Conclusion: Based on the results of the present study there is a significant relationship between, IT, RFA and BMD (p value=0.001).

Traditional implementation of sliding-mode controllers, based on hysteresis comparators, exhibits variable switching frequency. Such a condition makes it difficult to select the semiconductor devices, design the passive elements of dc/dc converters, and design the sensing filters usually adopted for removing the switching noise from currents and voltages. Those problems are always present in photovoltaic systems based on variable-frequency sliding-mode controllers. Therefore, this paper proposes an implementation methodology for sliding-mode controllers providing constant switching frequency, which is aimed for grid-connected photovoltaic applications. The proposed solution does not compromise the power production of the PV system, hence it provides the same PV power in comparison with the classical variable-frequency implementation. Finally, the performance and correct operation of the fixed-frequency implementation are demonstrated using both simulation and experimental results.

This paper presents a new load frequency control (LFC) design in a multi area power system by using local observers. Firstly, sliding mode observers with unknown inputs are designed for each area to estimate the state variables locally. In this stage interconnections and load variations are assumed as unknown inputs. Then, local state feedback and output integral are used to attenuate the effect of load variations in each area. Analysis and simulation results for a three-area interconnected power system show improvements on closed loop performance in comparisons with other existing methods.

In this article, the sliding mode control of frequency load control of power systems is studied. The study area consists of a system of water and heat. First, a mathematical model of the proposed system disturbances is made and then sliding control mode for frequency load control is provided. By the system simulation and sliding mode control, it can be shown that the damping of oscillations is well led.

This paper presents an empirical mode decomposition (EMD) based adaptive filter (AF) for channel estimation in OFDM system. In this method, length of channel impulse response (CIR) is first approximated using Akaike information criterion (AIC). Then, CIR is estimated using adaptive filter with EMD decomposed IMF of the received OFDM symbol. The correlation and kurtosis measures are used to select the useful IMF component from among available IMFs. Conventional AF uses random initial weight vector. The novelty of the proposed method is that it uses decimated version of one of the decomposed IMFs of received OFDM symbol as initial weight vector. This makes the proposed EMD based AF method converge to minimum mean square error (MMSE) in less number of iterations resulting in almost 50% saving of computations. The simulation studies in terms of bit error rate (BER) and mean square error (MSE) calculations established the efficacy of proposed method; and comparative studies under different modulation schemes and fading conditions revealed improved performance.

Seismic imaging is highly dependent on the quality of seismic data. Structural and stratigraphic interpretation of seismic sections that contain the least amount of noise is much easier. Reflection seismic data are often associated with noise. Coherent noise is a major category of noise that accompanies seismic data, and has the same trend in different seismic traces of the data. Ground roll is one of the main coherent noises that has a low frequency, high amplitude and low velocity. Various methods, such as frequency filters and frequency-wavenumber filter, have been used for ground-roll attenuation. Different advantages and disadvantages are mentioned for each of the methods. In this paper, we have used time – frequency transform and variational mode decomposition to attenuate the ground-roll.

In this study, a robust controller for voltage regulation of a POESLL converter operated in continuous conduction mode is presented. The POESLL converter is a DC/DC converter with a high voltage gain. DC/DC converters are used in telecommunication systems, power sources and industrial applications. Owing to the switching operation, the structure of the POESLL converter is non-linear. In addition, because of the load and input voltage variations, the structure of the POESLL converter is time-varying. In order to regulate the output voltage of the POESLL converter, a non-linear controller is required. The proposed controller is developed based on constant frequency sliding mode method. The sliding mode controllers can cope with the non-linear and time-varying structure of the DC/DC converters. The performance of the proposed controller is studied in PSIM software. A laboratory model of the proposed controller has been implemented. In this paper, design, simulations and experimental results are presented to show the effective performance of the proposed controller for voltage regulation of the POESLL converter.

Introduction: Patent ducfus arteriosus (PDA) is the persistence of a normal fetal structure between left pulmonary artery and descending aorta. Persistence of this fetal structure beyond 10 days of life is considered abnormal. In this study we compared M-Mode and Doppler echocardiography in diagnosis of PDA in children at Aliasghar Hospital in Zahedan and Children hospital in Bandar Abbas for one year. methods: We selected 62 patients that were suspicious to have PDA on physical examination. It should be mentioned that we omitted patients with other cgngenital cardiac abnormalities such as truncus arteriosus, ASD, VSD and AZSD. Our patients were below 15years old. Before echocardiography, physical examination, CXR and ECG were done for the patients. Then, they were evluated with both M-Mode and Doppler Echocardiography and finally results were statistically analyzed.Results: Out of 62 patients, 34 were female and 28 were male. 51.6% patients were less than one year old and others were older. 85% of patients had cardiac murmur on physical examination and in 50% of them pulmonary component of second heart sound was increased. Peripheral pounding pulses were present in 85% of patients. In chest X-Ray, 82.3% of patients had increased cardiothoracic ratio and pulmonary vascular markings were increased in 85.5% of them. On ECG, 58.1 % of patients had signs of right and left or bilateral ventricular hypertrophy. Pulmonary hypertension was also seen in 51.6% of patients. PDA was diagnosed with M-Mode echocardiography in 56 patients (90.3 %) and with Doppler echocardiography in 61 patients (98.4%). According to McNemar statistical analysis, there was not an obvious difference between these two. methods of echocardiography in PDA diagnosis (p=0.125).Conclusion: Findings of this study showed that M-Mode and Doppler echocardiography for diagnosis of PDA in children are similar and again attention to M-Mode echocardiography can be helpful in diagnosis of PDA in children especially restless infants and neonates.