Synthetic JETs, whose size and weight can be reduced easily, have become an attractive alternative to continuous JETs. Many experimental and numerical studies have been conducted on synthetic JETs to investigate their fundamental flow characteristics, including JET structure, for applied research such as boundary layer control and enhanced fluid mixing. However, few studies have focused on fluid transportation devices using synthetic JETs as a driving source. Therefore, several issues concerning fluid transport characteristics still need to be resolved. In addition, although optimum operation of devices using synthetic JETs is essential for their practical use, few studies have focused on this issue. The present study experimentally demonstrates the influence of the dimensionless stoke L on the performance characteristics of a synthetic JET FAN under Reynolds number Re = 1800 and the same FAN geometry; here, the stroke l is nondimensionalized by the primary slot width b. Furthermore, numerical simulations are conducted to complement the experiment. Velocity and pressure measurements are performed using a hot-wire anemometer, differential pressure manometer, and pressure transducer. The influence of the dimensionless stroke L on the performance/efficiency curves, static pressure distribution on the duct surface, and unsteady flow characteristics are investigated. Moreover, the flow field inside the duct is observed through numerical simulation. The results show that the performance characteristics and pressure recovery process depend on the dimensionless stroke L, and an optimum range of dimensionless stroke L exists for operation.

The mechanical ventilation smoke management system involves the use of supply FAN, JET FAN, and exhaust FANs, which are activated at different times after a fire is extinguished. This paper numerically investigates the effect of the priority and delay of smoke management systems on smoke distribution and visibility in a car park after a fire, using Fire Dynamic Simulation Code 6.7.6. The flow rates of the exhaust FAN, supply FAN and JET FAN are 1.9 m³/s, 1.43 m³/s, and 1.67 m³/s, respectively. The fire, located near the supply FANs, is modeled as a rectangle with dimensions of 2.0 × 0.8 m² and a power of 1.6 MW, lasting for one minute from ignition to extinguishment. Polyurethane is assumed as the flammable material. The priority and delay of the smoke management systems are evaluated through four scenarios over a period of 420 seconds. The results show that visibility reaches acceptable levels in all scenarios at all locations after 420 seconds. Additionally, the results indicate that the visibility of the upper half is highest for scenario a, at around 15 m. However, the visibility of the lower half is highest for scenario d, ranging between 20 and 30 m. It can be concluded that delaying the activation of smoke management systems is an effective strategy for facilitating smoke removal and fresh air intake.

The domain of Very Large Scale Integrated (VLSI) circuit testing has experienced advancements in methodologies for fault detection, which are crucial for addressing the complexities of modern applications. Traditional testing techniques frequently fall short in achieving precise fault localization, highlighting the necessity for the development of enhanced methodologies. This paper endeavors to investigate the implementation of an optimized test generation algorithm aimed at improving testing efficiency and increasing fault coverage. In this study, we utilized a (PSO)-enhanced FAN (FAN-out-oriented algorithm) applied to ISCAS'89 benchmark circuits. The optimization process involved refining the decision trees utilized in the FAN algorithm through a rigorously defined cost function, which strikes a balance between accuracy, complexity, and operational efficiency. The results indicate improvement in both fault coverage and detection efficiency. Furthermore, the optimization process resulted in a reduction of required test vectors, thereby enhancing testing efficiency, particularly in high-volume production environments. The study also introduces the development of diagnostic metrics that provide deeper insights into circuit failures and proposes design-for-testability techniques to improve reliability. The integration of PSO within the FAN algorithm not only facilitates the generation of robust test solutions but also produces high-quality test vectors.

in this research, their effects on the flight of airplanes were investigated. The study area is the country of Iran, and the flight routes of Kermanshah, Ahvaz and BandarAbbas to Tehran. The research data includes maps of the Vertical Transect (profile) of the JET stream, the daily average of the Zonal wind (U-Wind) and meridional wind (V-Wind) components for the winter period of 2018 through NOAA/NCEP environmental databases. Also, flight route information was received from FlightRadar24 and Flightaware systems. First, by using Vertical Transect maps, the days containing strong U-Wind were extracted, and the average position of the core of the JET Streams in the Zonal and meridional wind components, the Tropospheric level of 200 HP was detected. The list of flights was prepared, and the Zonal Wind maps were produced. Finally, the height of the flights was compared with the level of the currents of the JET Streams, and the influence or lack of influence of the JET Streams on the flights was studied. According to the results of the research, all the JET Streams caused turbulence for all flights, and they caused a decrease in the speed of flights between Ahvaz and BandarAbbas to Tehran and an increase in the speed of flights between Kermanshah and Tehran according to the direction and type of JET Streams. It was also found that all the JET Streams had a speed of more than 90 knots, so the capacity to create tension and turbulence such as CAT was seen in them

This paper investigates the influence of a weak-JET on the development of a turbulent axisymmetric strong JET. A parametric study is carried out to evaluate simultaneously the effect to the JETs-spacing (S/D=3 and S/D=7. 5) and their velocity ratios in range 0≤ λ ≤ 1. The mixing phenomenon is studied numerically by the finite volume method using the 3D-RANS second-order model, which gives a good agreement with the available data. Three distinct regions of this type of JETs interaction are evidenced. This study confirms that the JETs spacing affects strongly the converging region and has a minor effect on the combining region. It is found that the weak JET attracts the strong JET and the combining region extends from 30D to 40D where the self-similarity of a single JET is obtained. The JET width decreases when velocity ratio and JETs spacing augment. In the combining region, in comparison with the free JET, it is found that the addition of a weak-JET increases the decay rate of the centerline velocity.

Nowadays ventilation of railway tunnels in Iran with regard to their age and the need for increasing the traffic lines, especially for the west part of the country, is of paramount importance. The most important factors affecting ventilation design of these tunnels are heat and the gases produced by fuel combustion in diesel engines. The heat produced by these engines may increase the temperature of the air in tunnels so that locomotive motors are not able to operate with a reasonable efficiency. Products resulting from fuel combustion may also cause problems for the tunnel users. Therefore, ventilation of the tunnels should be designed with respect to these two aspects. The method presented in this paper, which is the first scientific and practical step in this regard, is based on using present railway transportation facilities and approaching standardization of the appropriate required air inside the tunnel. Study in of different ventilation methods shows that excavation the galleries and connected shafts the air through which may be transferred, or installation of the equipment inside the tunnel are not technically and economically desirable due to lack of geotechnical surveys and therefore knowledge about the earth materials, elongation of the proposed galleries and shafts and finally lack of the clearance in tunnel. These considerations resulted in choosing the method of installing a powerful JET FAN outside the tunnel and using the air-tight gates, one of the advantages of which is prevention of interference between the maintenance procedures with the train movement. In this paper the requirement for installation of ventilation facilities in the railway tunnels in Lorestan province in the west of Iran, with particular emphasis on the 102 Lorestan Railway Tunnel has been discussed. First of all the possibility of applying the different methods of ventilation in this tunnel was studied and according to the geometric conditions of the tunnel and topographical situation of the area, the possibility of using the hand dollies and access tunnels was disregarded. The transverse and semi transverse ventilation systems was not preferred either, due to the complexity of these systems compared to longitudinal ventilation systems.Finally application of strong FANs with 130m3/sand the 3 KPa pressure and an engine with 600 KW power along with utilization of ventilation gallery with 50 m length and 150 angle towards the main tunnel and airtight doors, has been selected as the optimal ventilation systems for this tunnel.

To understand the JET flow characteristics of turboFAN separate exhaust system, a parametric design method based on the initial Class Shape Transformation function was developed. HBPR and UHBPR turboFAN separate exhaust systems were designed. Furthermore, the JET flow characteristics of the HBPR turboFAN exhaust system under take-off condition with zero angle of attack were studied based on numerical simulation. The JET flow characteristics of the HBPR and UHBPR turboFAN exhaust system under take-off condition with high angle of attack were also simulated. The effects of angle of attack and bypass ratio on the JET flow characteristics were investigated and the related flow mechanisms were analyzed. Results show that the axisymmetric plumes of the HBPR turboFAN exhaust system are distributed around the engine axis under take-off condition with zero angle of attack. With the plug wake as the center, the core flow, the FAN/core shear layer, the FAN flow, the FAN/free stream shear layer and the free stream are wrapped around the plug wake from inside out. Vortexes appear in the lee area at the back of the cowl and JET flow under take-off condition with high angle of attack. These vortexes cause cross sectional secondary flow and expose the high-velocity core flow to the low-velocity free stream. The contact area and velocity gradient in the mixing region among the free stream, FAN flow and core flow increase. Therefore, the mixture among JET flow and free stream strengthens. So the high-velocity region, the high-vorticity region, and the high turbulence kinetic energy region shorten by 55. 1%, 47. 7% and 50. 9% respectively. The vorticity values and turbulence kinetic energy level peak on the upper side of the exhaust plumes increase by about 30% and 87% respectively. Relative to these parameters from the HBPR turboFAN exhaust system, the JET velocity peak value of UHBPR turboFAN decreases by 5. 5% under take-off condition with high angle of attack. The vorticity values and turbulence kinetic energy level reduce due to decreased velocity gradient in shear layers downstream of the nozzle exit plane. The turbulence kinetic energy level peak on the upper side of the exhaust plumes decreases by 29. 3%. The reasons are that the contact area between high-velocity core flow and the free stream decreases due to thicker FAN flow and the velocity gradient in the core flow and free stream mixing region decreases because of the lower core flow velocity.