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Showing 4 results for Numerical Optimization

Gholam. Hossain. Liaghat, Habib-Ala. Sorailo,
Volume 9, Issue 1 (12-2009)
Abstract

A honeycomb panel consists of an array of open hexagonal cells which their walls are perpendicular to face sheets although other panel sandwiches don’t have these perpendicular walls. Their design is often performed based on minimum weight. This research is aimed at minimizations of weight by means of computing honeycomb core girth. Weight optimization is done by means of Naive and numerical procedures. Numerical optimization is done by the sequential quadratic programming (SQP) method. Geometric parameters and optimized weight are calculated for hexagonal and square cells. Optimized weights for these two cross-sections are compared. Keywords: Honeycomb Weight Optimization, Sandwich Panels, Numerical optimization, Sequential Quadratic Programming.
Hassan Zohoor, Safoora Tahmasebi,
Volume 16, Issue 12 (2-2017)
Abstract

In recent years, knee diseases are spread especially in elderly people. Since performing daily activities such as walking and running, the knee supports the weight of the body, there is more likely to be injured. This issue is more important for elderly people who have weak muscles and almost all elderly people suffer from knee pain. One way to help this people in order to move normally is to use a wearable device to aid the knee. In this article, a passive wearable robot will be designed to improve the strength of the elderly who suffers from the knee pain. The robot uses the compliance elements to increase the power of the knee joint in parts of a cycle. This robot will be developed based on a Stephenson II six-bar mechanism. Using this mechanism has the advantage of producing the similar motion to a knee. In other words, this mechanism produces the linear and rotational motions simultaneously. Additionally, more compliance elements can be added to improve the performance of the wearable robot. The optimal dimensions of the robot will be Through the kinematics analysis and also the derivation of the dynamics equations and the numerical validations of these equations, the performance of the robot will be considered. The performance of the robot mounted on the leg is compared with the human. Obtained results show that the less power is required when a wearable robot is used. This proves the merits of the designed robot to be used for the elderly.
Afshin Kazerooni, Hossein Akbari,
Volume 17, Issue 10 (1-2018)
Abstract

In this paper the principles of simultaneous measurement of three orthogonal force vectors Fx, Fy, Fz and three orthogonal torque vectors Mx, My, Mz to design a six axis force/torque sensor are considered. At first, a new index (η) for a qualitative comparison of six-axis force/torque sensors is proposed and then, cross-coupling error of several sensors presented in previous studies is evaluated and compared by using the new index. In the following, a systematic method for designing the six-axis force/torque sensor is described using numerical optimization procedure. This method is based on interactive interface between the SQP algorithm created in MATLAB and FEM analysis in ANSYS software. The geometry of sensor structure is selected to be a modified Maltese cross type. Principle cross-coupling error is chosen as the objective function to optimize four geometrical design variables of the sensor structure. Also, strain gauge sensitivity, maximum applied stress and geometric sizes of the sensor structure as constraints are formulated in problem. Results show that principle cross-coupling error of the optimal sensor design is less than 1.49% with a high moment to force specification (0.1 N.m/N).

Volume 23, Issue 4 (12-2023)
Abstract

Introduction:
 In order to target the limited budgets of poverty alleviation programs and increase their efficiency, a wide range of targeting methods including means testing, proxy means testing, categorical targeting, geographical targeting, self-targeting, and community-based targeting has been used  in developing countries (Coady, Grosh and Hoddinott, 2004). However, targeting in Iran, in the best case, has been based on the proxy means testing. Kidd and Wylde (2011) have criticized this method due to lack of transparency and poor predictions in the field of identifying the poor. The main purpose of this article is to compare the different economic and social characteristics of Iran’s rural households with the aim of finding the best characteristics in order to target subsidies in Iran. In this context, the following questions are raised: In a situation where accurate information about household income or expenses is not available, how should households be prioritized to receive subsidies based on their characteristics? How much cash subsidy should each household receive in order to reduce the aggregate poverty? To answer these questions, by following, Kanbur (1987), Ravallion and Chao (1989), Elbers, Fujii, Lanjouw, Özler and Yin (2007), Glewwe (1992) and Araar and Luca (2019), I use a new numerical algorithm, which acts as optimal poverty group targeting. This method is conceived to find the optimal group transfers that allow the largest possible reduction in any additive poverty indexes, like the Foster, Greer, Thorbecke (FGT) class of poverty indexes.
Methodology:
This article uses a new numerical algorithm, which acts as optimal poverty group targeting. This method was first presented by Kanbur (1987), which focused on the theoretical rules of optimization. Then, based on the theoretical findings of Kanbur (1987), Ravallion and Chao (1989) have proposed numerical method that maximizes the reduction in the FGT (
α=2)  index by group transfers, subject to a fixed budget. After that, Glewwe (1992) improved it theoretically, and finally, Araar and Luca (2019) proposed the method of optimal group targeting by modifying Glewwe (1992) method. In fact, the methodology of Glewwe (1992) is a generalization of Kanbor (1987) and Ravallion and Chua (1989) Method, but the mentioned methodologies focused on a subset of poverty indicators (e.g., squared poverty gap index) for which an analytical solution was possible. Contrarily, Araar and Luca (2019) proposed a new method, which is applicable to all additive poverty indices (such as the headcount or poverty gap rates and squared poverty gap indexes).This article uses income-expenditure data of rural households of Iran in 2020, and follows Araar and Luca (2019) methodology. In addition, to check the efficiency of this method, three indicators including the quality of targeting, inclusion and exclusion errors will be used.
Results and Discussion:
In this article, economic and social characteristics of rural households in Iran were compared to targeted poverty alleviation programs. Based on the results, for the head count ratio, the targeting efficiency based on different household characteristics changes between 23.67 and 31.03 %, the population coverage rate changes between 38.93 and 100 %, and the sum of the inclusion and exclusion errors changes between 41.62 and 52.53%. Now, if the targeting is done based on the poverty gap index, the targeting efficiency will be between 42.18 and 48.02 %, the population coverage rate will be between 86.21 and 100 %, and the sum of the exclusion and inclusion errors will be between 46.96 and 52.53%. Finally, if the poverty severity index is used as the basis for targeting, the targeting efficiency will change between 53.99 and 59.51 %, the population coverage rate will change between 99.33 and 100 %, and the sum of the inclusion and exclusion errors will change between 48.92 and 52.53%. It is interesting to note that in targeting based on all three mentioned poverty indicators, the family size, number of members under 7 years old and the education of the household head are always the best characteristics for targeting poverty.
Conclusion:
The main purpose of this article is to compare the different economic and social characteristics of rural households with the aim of identifying the best characteristics in order to targeting subsidies in Iran. According to the results of this article, the characteristic that should be taken into account in targeting is the family size, which the efficiency of targeting based on this characteristic is equal to 51.59% of targeting with complete information. The rate of exclusion and inclusion errors are zero and 52.53%, respectively. Finally, in the targeting based on the family size and squared poverty gap index, the population coverage rate is 100, which is very acceptable from the social point of view.  Paying attention to the changes in the poverty indices based on the household demographic characteristics is very important, because if the family size increases, the poverty indices grow strongly. As a result, the headcount, poverty gap and squared poverty gap indexes for families with six and more people become 2.5, 3.5 and 2.4 times the same index for households with 1-2 people, respecti
vely.


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