Numerical Modeling of Fluid Behavior on the Body of a Concrete Double-Arched Dam Considering the Interaction of Water and Structure under Impact Loads

One of the greatest issues regarding Iranian concrete dams is the lack of consideration for increasing our knowledge about them and their performance in times of accidents such as floods, earthquakes, and impact load caused by explosion waves. Some of the most significant objectives of this research are an investigation of the effect of TNT content and its distance from the concrete dam, the identification of critical points of the dam, and the impact of fluid on the amount of damage caused by the explosion to the concrete dam under impact load. The analysis used in this research is straightforward. It should be noted that the discovery of the critical points of the dam in the event of an accident, such as an explosion with complex behavior, can minimize human and financial losses. The LBE method was employed in this study. The interaction between the dam and the water behind it is one of the very considerable parameters that influence the deformation of the dam due to the hydrodynamic pressure of the water behind the dam. It is demonstrated by the results that doubling and tripling the amount of TNT leads to an increase in the pressure on the crest of the full dam by 46.63% and 64.68% respectively; besides, by multiplying the amount of TNT by four and five, the mentioned pressure increases by 70% and 75.58%, respectively

The effect of short pin fin aspect ratio on thermal characteristics of intermittent impinging jet; An experimental and numerical study

Background: Pin fins are secondary surfaces extending from an object to enhance the heat transfer rate. Pin fin is one of the most effective practical techniques used in many industrial applications and thermal treatments especially for cooling electronic devices. Also, Pulsating flow is extremely used in the machinery industry and it can improve the heat transfer. Therefore, pulsating flow is combined with an extended surface to enhance the heat transfer efficiency. Methods: The current paper investigates numerically and experimentally the intermittent impingement flow and consequence heat transfer characteristics in the presence of a pin-fin array over a flat plate. The RNG k − ɛ model is employed to simulate unsteady three-dimensional turbulent flow using CFD software. The influences of jet Reynolds number, pulsation frequency, jet-to-surface distance, and aspect ratio on the distribution of the area-time averaged Nusselt number are studied. 36 elliptical pin-fins considered at three rows on the surface, placed at r/ D = 3, 5, and 7 (36, 60, and 84 mm) from the central point of the jet. Considering the influence of the aspect ratio on the streamline and temperature patterns of the flow, numerical simulations were conducted in various pin-fin diameters of 4–12 mm. Significant findings: From the experimental data, the results indicated that there is a specific frequency that the heat transfer increases for Reynolds numbers in the range of 10,000–20,000. The results illustrated that the rate of heat transfer is reduced with rising the diameter of the pin fin for AR>1, whereas it is enhanced for AR<1. The area-time averaged Nusselt number is enhanced with rising aspect ratio at various pin fin heights. For Re=10,000, the heat transfer rate decreases with increasing the jet-to-surface distance in steady state while it increases for pulsating flow. Also, the maximum value of turbulent kinetic energy appears nearby the pin-fin owing to the formation of a horseshoe vortex. The vortex structures are strengthened and grow downstream, as the frequency increases

Aerothermal analysis of pulsed jet impinging on a flat surface with different pin configurations

In this work, the effect of a pin as a secondary surface mounted on hydrothermal behavior of impinging jet over a flat plate investigated numerically and experimentally. The transient three-dimensional turbulent flow is simulated by the Renormalization Group (RNG) k − ɛ model. The injection air is pulsed by square waves. In a radial arrangement, several differently shaped pins (i.e., circular, elliptical, and square) with the same cross-sectional areas are compared. Three Reynolds numbers (10,000, 15,000 and 20,000) and four pin-to-injection point distances (r = 2D, r = 3D, r = 4D and r = 5D) are considered. Within the experimental range, the results indicated that the use of a pulsating jet in the frequency range of 50–100 Hz enhances the rate of heat transfer. The rate of heat transfer of the square pin is less than that of the smooth surface. Based on specific performance parameters, the elliptical pin is found to be a favorable alternative configuration to a circular pin. Also, the results showed that the appropriate position to mount the pin on a flat surface at a radial distance is three times the diameter of the jet (r = 3D) for elliptical and circular pins

Image security using steganography and cryptography with sweeping computational ghost imaging

A sweeping computational ghost imaging (SCGI)-based encryption system is intended for increased data security and speedier data transport. SCGI is combined with steganography and cryptography processes in this system. SCGI requires fewer shots, resulting in faster image capture, transmission, encryption, and decryption. This strategy also results in smaller, more compact data packages and higher bitrates. Least significant bit (LSB) uses steganography to conceal the hidden picture. In the case of Rivest–Shamir–Adleman (RSA) encryption, public and private keys are generated via a one-way function based on bucket values. Encryption is performed on two levels, with an asymmetric approach divided into three sub-items that significantly increase encryption. Surprisingly, the method uses fewer pictures for image reconstruction, resulting in faster image reconstruction. SCGI promises applications in an extensive number of data encryption sectors since this technology leads to smaller data packages and higher bitrates. The presented approach is examined using the number of pixel change rate (NPCR), normalized root mean square (NRMS), peak signal-to-noise ratio (PSNR), and correlation coefficient (CC), which indicates constant encryption improvement. We experimentally and situationally demonstrate our findings under eavesdropping, which prove the resistance and robustness of our methods. In optimal settings, this innovation enhances encryption by up to 90% when compared to traditional encryption methods

Association between incidence of atrial fibrillation and duration of cardiopulmonary bypass in coronary artery bypass graft surgery (CABG): a cohort study

Background: Open heart surgery is one of the most common and valuable treatment methods for cardiovascular diseases, a common side effect of which is atrial fibrillation that occurs due to various reasons. Objective: To determine the relationship between incidence of atrial fibrillation (AF) and duration of cardiopulmonary bypass (CPB) in patients after open heart surgery. Methods: The present retrospective cohort study was conducted on 330 patients in Farshchian Heart Center through census. The required data were collected from medical records of the patients undergoing coronary bypass surgery using data collection between April 2015 and March 2015. Then, data analysis was performed using SPSS software (ver.16) at error level of p<0.05. The tests used in this study included independent-samples t-test, Mann-Whitney, and chi-squared tests. Results: Based on the results, mean age of the patients was 61.76±9.2, the majority of the patients (70.1%) were male. The association between Incidence of Atrial Fibrillation and cardiopulmonary pump time (minute) was not meaningful. Incidence of atrial fibrillation had statistically significant relationship with variables of mean age, BMI, PAC, PVC, creatinine and duration of hospitalization (p<0.05); on the other hand, variables of gender, cross clamp time (minute), intubation time (hour), and clinical history had no effect on atrial fibrillation incidence rate (p>0.05). Conclusion: Since the pathogenesis of AF after cardiac surgery is believed to be multifactorial, including clinical variables and technical intraoperative factors, the relation between incidence of AF with mean age, BMI, PAC, PVC, creatinine and duration of hospitalization was significant. But AF was not related to cardiopulmonary pump time (minute). It is necessary to conduct further research on factors affecting incidence of atrial fibrillation

The Effects of Two-Week Swimming Training on Neuropathic Pain Induced by Chronic Constriction Injury and the Expression of GAD65 in Adult Male Rats

Background & Objective: Unknown mechanisms are involved in neuropathic pain. Among the non-pharmacological treatments, it seems that physical activity improves neuropathic pain. However, the possible reasons for the effectiveness of regular physical activity on neuropathic pain are unknown. Therefore, the present study was performed to determine the effects of two-week swimming training on the expression of GAD65 enzyme and P2X3 receptor in Chronic Constriction Injury (CCI) of the sciatic nerve. Materials & Methods: 40Wistar adult rats were divided into five groups randomly: 1) CCI neuropathic pain with swimming training (CCIST2); 2) CCI neuropathic pain without swimming training (CCI); 3) No CCI neuropathic pain with swimming training (ST2); No CCI neuropathic pain without swimming training (control group); 5) CCI sham surgery (Sham CCI). CCI and CCIST2 groups underwent peripheral nerve injury by four loose ligatures around sciatic nerve. Swimming program included two weeks with five sessions per week, and 30-60 min per session. The protein expressions of GAD65 enzyme and P2X3 receptor were evaluated by western blotting technique. Results: CCI surgery decreased the expression of GAD65, but two weeks swimming training increased expression of GAD65 comparing to CCI and Sham CCI groups (P&le;0.001), but P2X3 receptor expression were not significantly different among groups in lumbar segment of rats (P>0.05). Conclusion: Totally, our findings showed that two-week swimming training improves neuropathic pain possibly through maintenance of inhibitory neurons and subsequently increased GAD65, which converts glutamate excitatory neurotransmitter to GABA inhibitory neurotransmitter