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Issue Info: 
  • Year: 

    2024
  • Volume: 

    37
  • Issue: 

    8
  • Pages: 

    1475-1485
Measures: 
  • Citations: 

    0
  • Views: 

    7
  • Downloads: 

    0
Abstract: 

This study addresses interceptor devices to improve the hydrodynamic characteristic of autonomous unmanned surface vehicle (USV). The bulb and rectangular interceptors had molded on a planning hull. This research aims to mitigate drag impact on rectangular interceptors at high speeds. According to this study, a bulb interceptor had a better impact than a rectangular interceptor. This research is based on the finite volume method (FVM) with dynamic fluid-body interaction (DFBI), which captured the ship’s dynamic trim and sinkage. The simulation used an overset mesh technique with two domains as a donor-acceptor cell. Furthermore, numerical calculations using the Reynolds-Averaged Navier-Stokes equation and the k-turbulence model predict the turbulent flow. Grid independence studies and international towing tank conference (ITTC) recommendations have been applied to ensure simulation accuracy. This study reported that the bulb interceptor had effectiveness between 9%-25% compared to the rectangular interceptor at high speed. This research showed that the bulb interceptor had better effectiveness than the rectangular interceptor.

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Issue Info: 
  • Year: 

    2024
  • Volume: 

    13
  • Issue: 

    25
  • Pages: 

    3-32
Measures: 
  • Citations: 

    0
  • Views: 

    16
  • Downloads: 

    0
Abstract: 

In this research, in order to investigate the effect of the piezoelectric patch which is used as a sensor or actuator in rotating flexible structures such as a helicopter blade, the free vibrations of the rotating rectangular sheet with and without the piezoelectric patch have been presented. First-order shear deformation theory is considered for plate displacement and piezoelectric field. Considering the effect of Coriolis acceleration, centrifugal acceleration and centrifugal in-plane forces, the equations of motion are derived from Hamilton's principle and the electromechanical couple equation is obtained from Maxwell's equation. For piezoelectric, two electrical conditions, open circuit and closed circuit, which are used in sensors and actuators, respectively, have been considered. The equations are discretized with the help of the numerical method of generalized differential squares and the matrices of inertia mass, eccentricity, Coriolis and stiffness matrix are obtained. Natural frequency values for beam and rotating plate have been compared in Abaqus software. Also, the values obtained from the numerical solution in MATLAB have been verified with articles and ABAQUS, which have high accuracy. The effect of parameters such as hub radius, rotation speed, sheet thickness, aspect ratio, piezoelectric patch thickness and applied voltage on the natural frequency of the system has also been investigated.

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Issue Info: 
  • Year: 

    2024
  • Volume: 

    13
  • Issue: 

    6
  • Pages: 

    59-73
Measures: 
  • Citations: 

    0
  • Views: 

    48
  • Downloads: 

    11
Abstract: 

The integrated design method for a missile guidance and control system is such that all the limitations of the subsystems are taken into account during the design in a bid to increase the accuracy and overall performance of the system in the final phase. This will improve efficiency, save time and implementation cost, and as a result, system performance will improve. This article describes the process of designing and simulating the performance of the neural sliding model controller, which was created to guide the missile in a two-dimensional engagement in minimizing the collision time and the miss distance to the target. In the design of the controller, a PID is first considered to evaluate the proposed controller, followed by the design of the neural sliding model controller discussed using neural networks. According to the simulations, it can be shown that the use of this proposed controller and the application of the integrated guidance and control model will reduce the final miss distance and the collision time compared to the PID controller.

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Issue Info: 
  • Year: 

    2020
  • Volume: 

    51
  • Issue: 

    8
  • Pages: 

    1895-1905
Measures: 
  • Citations: 

    0
  • Views: 

    462
  • Downloads: 

    0
Abstract: 

Climatic conditions and soil properties such as salinity are very important and influential factors in vegetation of any region. The salinity of the groundwater and the accumulation of salts in the surface layers of the soil due to evaporation and capillary rise have caused salinization in a part of Qazvin plain that has had adverse effects on the growth of plant species in an area of 60, 000 hectares. In order to control the devastating effects of Salt Marsh development in the area, interceptor drain has been constructed in the central Salt Marsh core. The purpose of this study was to analyze the Effectiveness of interceptor Drain on Soil Salinity and Vegetation Changes during 5 years with 10 exclosures. To investigate the effects of drain construction, the statistical analysis was performed in a factorial randomized complete block design. The results show that the electrical conductivity of deep soil is 18% more than the electrical conductivity of surface soil. The results of comparing the average soil electrical conductivity based on Duncan's method showed that the average soil electrical conductivity was highest in 2013 and the lowest in the fourth year after the beginning of the study. Since the main source of soil leaching in the area of excavated crops is runoff, therefore the most important cause of soil electrical conductivity variations with different years can be related to the amount of spring rainfall. The results of statistical analysis showed that the electrical conductivity of the soil decreased gradually by passing years in the constructed exclosures. The results of variance analyses of vegetation percentages in exclosures showed that the constructed interceptor drain has had a significant effect on vegetation changes during the studied years and the spatial effectiveness of the drain on vegetation changes has been 300 m.

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Issue Info: 
  • Year: 

    2008
  • Volume: 

    19
  • Issue: 

    1
  • Pages: 

    123-131
Measures: 
  • Citations: 

    0
  • Views: 

    1391
  • Downloads: 

    0
Keywords: 
Abstract: 

Packing rectangular shapes into a rectangular space is one of the most important discussions on Cutting & Packing problems (C&P); such as: cutting problem, bin-packing problem and distributors pallet loading problem, etc. Assume a set of rectangular pieces with specific lengths, widths and utility values. Also assume a rectangular packing space with specific width and length. The objective function is, to pack the pieces into the space in Order to get the maximum sum of utility value of the packed pieces. To generate the related packing pattern this paper proposes a new formulation metl10dbased on the column generation, approach. In this method one each cycle of the algorithm; a one-dimensional pattern is generated based on the shadow prices 'Of the Simplex method. The set of generated one-dimensional patterns are used: to construct the two-dimensional packing pattern. Also, the proposed model and the present models in the.state-of-1beart have been compared.

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Issue Info: 
  • Year: 

    2020
  • Volume: 

    10
  • Issue: 

    34
  • Pages: 

    37-52
Measures: 
  • Citations: 

    0
  • Views: 

    907
  • Downloads: 

    0
Abstract: 

Soil salinity and soil salinization as one of the problems facing agriculture and natural resources are of great importance which needs to be prevented with proper knowledge. In this regard, it is important to obtain information about soil salinity and vegetation, such as their amount and distribution. The use of satellite data enables extensive study of soil salinity and vegetation. Since vegetation in most arid and semi-arid regions is strongly influenced by soil properties such as salinity, therefore, this study investigated the effects of interceptor Drain on soil salinity and vegetation changes using remote sensing capabilities in a 15-year interval. Results showed that construction interceptor Drain in Salt Marsh Qazvin plain had no effect on soil salinity changes and vegetation cover. According to the results of correlation test between measured soil elements and satellite image bands, bands 5 and 7 were highly correlated with soil SAR (Sodium Adsorption Ratio) index prior to drainage construction and thus, the two bands after drainage construction had a significant correlation with soil EC (Electrical Conductivity) index. In fact, indices including red and infrared bands showed a significant relationship with soil salinity parameters. Also the results of correlation test of remote sensing indices and ground data in the salinity area showed that SI (Salinity Index) index had a highly significant correlation with soil salinity data.

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Issue Info: 
  • Year: 

    2013
  • Volume: 

    7
  • Issue: 

    1
  • Pages: 

    31-45
Measures: 
  • Citations: 

    1
  • Views: 

    504
  • Downloads: 

    164
Abstract: 

Background: The Long-lasing insecticide impregnated nets (LLINs) is considered as an effective tools for malaria vector control. The aim of this study was to evaluate the residual efficacy of alpha-cypermethrin long lasting impregnated nets (LLIN-interceptorÒ) against Anopheles stephensi using tunnel test.Methods: The wash-resistance of interceptorÒ nets were assessed under laboratory conditions using tunnel test.Females of An. stephensi were released into the tunnel and then they were provided blood meals from guinea pigs.Bed nets were washed according to the standard procedure up to 20 times. The bioefficacy indicators such as inhibition of bloodmeal from experimental animal, knockdown, irritancy rate, survival rate, entry index and mortality were calculated.Results: It induced 90-100% mortalities in the population of An. stephensi up to 15 washes. The KT50 values reduced from 73.47 to 26.30 minutes in unwashed in comparison to one washed, respectively. The mean of mortality rate of blood-feeding inhibition and entry indexes was reached to 91.6%±2.8, 87.0±3.4 and 24.9±2.8 respectively after 20 washing.Conclusion: This net could provide a good personal protection against malaria vectors and could induce relatively high mortality, inhibit the blood-feeding as well as reduce the entry rates of female mosquitoes even after several washes.

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    12
  • Issue: 

    3
  • Pages: 

    143-163
Measures: 
  • Citations: 

    0
  • Views: 

    37
  • Downloads: 

    6
Abstract: 

We first prove that there always exists a maximal rectangularly dualizable graph for a given rectangularly dualizable graph and present an algorithm for its construction. Further, we show that a maximal rectangularly dualizable graph can always be transformed to an edge-irreducible rectangularly dualizable graph and present an algorithm that transforms a maximal rectangularly dualizable graph to an edge-irreducible rectangularly dualizable graph.

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Author(s): 

AKBARZADEH S.

Issue Info: 
  • Year: 

    2013
  • Volume: 

    13
  • Issue: 

    6
  • Pages: 

    43-51
Measures: 
  • Citations: 

    0
  • Views: 

    680
  • Downloads: 

    0
Abstract: 

Due to the energy concerns, it is always desired to run the mechanical elements under optimized operating conditions. Many lubricated mechanical elements such as gears, rolling element bearings, cam and followers etc. usually operate under mixed-lubrication regime. In this regime, both the lubricant film as well as the asperities contribute in carrying the load. The life span of these elements is divided into two regimes: running-in and steady-state. In this research an efficient model has been presented to predict the variation in asperities height during running-in. The predicted results are verified with experimentally-obtained published data. A parametric study on the effect of operating conditions such as load and speed as well as initial surface roughness and material hardness on the roughness variation during running-in has been conducted.

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Issue Info: 
  • Year: 

    2016
  • Volume: 

    29
  • Issue: 

    6
  • Pages: 

    1438-1446
Measures: 
  • Citations: 

    0
  • Views: 

    1759
  • Downloads: 

    637
Abstract: 

Introduction: Labyrinth weirs compare with straight weirs had required less freeboard in upstream so they are more appropriate for the irrigation networks. So they could maked more space to sotrage water and restrained foold with higher discharge. Labyrinths weirs have three generally form triangles, trapezoidal and rectangular that Tullis et al. (15) presented formula (3) for discharge coefficient of labyrinth weirs (triangles and rectangular) and a few studiescarried out on rectangular shape and its hydraulic characteristics are not specified.Therefore main aim of this paper study and characterized hydraulic characteristics of rectangular labyrinth weirs by using laboratory data.Materials and Methods: In this study rectangular labyrinth weir discharge and coefficient discharge relationships used dimensional analysis and experiment on hydraulic modeling, constant coefficient was defined.Laboratory flume is shown in Figure 2 (0.5 m wide x 12 m long x 0.8 m deep). Models was made from clear plexiglass plate with 10 cm thickness thatcuted using leaser device and the crest manualy shaped quadrant with radius 10 cm, all models using silicon glue install in the flume. The upstream depth readership by point gauge that installed in upstream of models. Discharge calcutaed byupsterm depth of triangular weir that installed in down stream of flume. Data were analyzed by SPSS software and to compare relationships with each other used two parameter root mean square error and correlation coefficient and charts darw in Excel Results and Discussion: discharge coefficient formula (11) carried out by using SPSS software that compared with formula (3). Results showed (Tables 2 and 3) that the correlation coefficient of formula (11) was more than a formula (3) and formula (11) RSME was less than formula (3) RSME except in first and fifth hydraulic model (rectengular1 and 5) that they were almost equal. So the formula (11) was more accurate than a formula (3) to peredict discharge of flow in flume. In previous step we used all data, we saw flourmloa (11) had more accurate then we diceded data divided in to three groups: high change, length change and all that calculated correlation coefficient and RSME for formula (11) to figure out which group have more accurate, results was brought in table 4. The result showed that constant coefficient of formula (11) yields from all data was useful for the design proposed. Plotted discharge changes against H/P for rectangular labyrinth and straight weirs in Figs.3 and 4. In constant discharge and high with raising length weir, decreased depth of flow over the weir because the effective weir length was raised and the ratio of distributed length to apex length (b) was decreased. As well as in constant H/P and high weir with raising apex length, discharge was increased that similarity of the results of Tullis et al. (15) and Khode et al. (8). In length, and the ratio H / P constant with increasing height in the discharge coefficient due to submergence reduce local side Jt Hay reduce interference, but increases with increasing height from 0.20 to 0.25m m discharge coefficient decreases as flow rate and Weber number decreased as a result of the effect of surface tension and increased resistance to flow. In length, and the ratio H / P fixed amount of overflow discharge increases with increasing height as the ratio H / P value of the denominator increases and therefore increases the total height of the water upstream. For design overflow rectangular labyrinth weirs recommends0.20£H/P£0.40that maximum aeration and discharge coefficient in this range is the result of Hay and Taylor (7) and Darvas (4) is consistent. In discharge and fixed weir height and maximum height of the water upstream directly at least equal to 1.8 of the overflow stright weirs. So for the areas where there is a height restriction of water upstream, the water level upstream of rectangular labyrinth weirs less direct overflow weirs requires the use of this is recommended.Conclusion: The results showed the relationship (11) that uses most of effective parameters has more accurate results and proposed for design aim. In constant water head upstream discharge of labyrinth weir maximum 2.6 times more than straight weir discharge and in constant discharge water head upstream of straight weir 1.8 times more than upstream labyrinth weir water head so use a labyrinth weir appropriate for areas that have head and discharge restrictions. Best range of ratio H/P for of design was 0.20 to 0.40 and maxim coefficient discharge happened in this range.

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