A Multi-Objective Optimization Approach for Multi-Head Beam-Type Placement Machines

This paper addresses a highly challenging scheduling problem in the field of printed circuit board (PCB) assembly systems using Surface Mounting Devices (SMD). After describing some challenging optimization sub-problems relating to the heads of multi-head surface mounting placement machines, we formulate an integrated multi-objective mathematical model considering of two main sub-problems simultaneously. The proposed model is a mixed integer nonlinear programming one which is very complex to be solved optimally. Therefore, it is first converted into a linearized model and then solved using an efficient multi-objective approach, i.e., the augmented epsilon constraint method. An illustrative example is also provided to show the usefulness and applicability of the proposed model and solution method.PCB assembly. Multi-head beam-type placement machine. Multi-objective mathematical programming. Augmented epsilon-constraint method

Exploring field scale salinity using simulation modeling, example for Rudasht area, Esfahan Province, Iran

Salinity / Simulation models / Soil-water-plant relationships / Soil properties / Climate / Irrigated farming / Water quality / Iran / Esfahan Province / Rudasht Area

Residues and dissipation kinetics of two imidacloprid nanoformulations on bean (Phaseolus vulgaris L.) under field conditions

The current study investigates the dissipation kinetics of two imidacloprid (IMI) nanoformulations (entitled: Nano-IMI and Nano-IMI/TiO2) on common bean (Phaseolus vulgaris) seeds under field conditions and compares them with 35% Suspension Concentrate (SC) commercial formulation. To do so, it sprays P. vulgaris plants at 30 and 60 g/ha within green bean stage, sampling them during the 14-day period after the treatment. Following extraction and quantification of IMI residues, dissipation data have been fitted to simple-first order kinetic model (SFOK) and to first-order double-exponential decay (FODED) models, with 50% and 90% dissipation times (DT50 and DT90, respectively) assessed along the pre-harvest interval (PHI). With the exception of Nano-IMI at 60 g/ha, other decline curves are best fitted to the FODED model. In general, dissipation is faster for Nano-IMI (at 30 g/ha: DT50 = 1.09 days, DT90 = 4.30 days, PHI = 1.23 days; at 60 g/ha: DT50 = 1.29 days, DT90 = 4.29 days, PHI = 2.95 days) and Nano-IMI/TiO2 (at 30 g/ha: DT50 = 1.15 days, DT90 = 4.40 days, PHI = 1.08 days; at 60 g/ha: DT50 = 0.86 days, DT90 = 4.92 days, PHI = 3.02 days), compared to 35% SC (at 30 g/ha: DT50 = 1.58, DT90 = 6.45, PHI = 1.93; at 60 g/ha: DT50 = 1.58 days, DT90 = 14.50 days, PHI = 5.37 days). These results suggest the suitability of Nano-IMI and Nano-IMI/TiO2 application at both rates in terms of their residues on P. vulgaris seeds

Materials Selection and Processing Techniques for Small Spacecraft Solar Cell Arrays

Body mounted germanium substrate solar cell arrays form the faces of many small satellite designs to provide the primary power source on orbit. High efficiency solar cells are made affordable for university satellite programs as triangular devices trimmed from wafer scale solar cells. The smaller cells allow array designs to pack tightly around antenna mounts and payload instruments, giving the board design flexibility. One objective of this work is to investigate the reliability of solar cells attached to FR-4 printed circuit boards. FR-4 circuit boards have significantly higher thermal expansion coefficients and lower thermal conductivities than germanium. This thermal expansion coefficient mismatch between the FR-4 board and the components causes concern for the power system in terms of failures seen by the solar cells. These failures are most likely to occur with a longer orbital lifetime and an extended exposure to harsh environments. This work compares various methods of attaching solar cells to printed circuit boards, using solder paste alone and with a silicone adhesive, and considering the application of these adhesives by comparing the solder joints when printed by screen versus a stencil. An environmental test plan was used to compare the survivability and performance of the solar arrays

Effect of personality type on internet anxiety in Kerman Dental School students (2015-2016)

Introduction and objective: in recent years internet has turned to be one of the most popular global medias due to its unique qualities such as easy accessibility, utilization convenience, users’ obscurity and low cost. This study targets at examining the personality types’ effects on internet anxiety in students of dental faculty in Medical University of Kerman.Methodology: This cross-sectional study was conducted on 235 dental students who were selected through census sampling method. Data collecting tools consisted of standard internet anxiety questionnaire (including 20 items), personality type’s questionnaire (including 25 items), demographic characteristics (age, sex, entrance year) and also eight related questions via internet. The collected data were entered the computer and analyzed via SPSS statistics software version 18 and linear regression statistics test and t at the significance level of 5%.Findings: From 235 participant students in this study 141 (66.0 %) were females and the rest were males and the average of their age was 23.85 ± 5.36. the mean score of internet anxiety was 54.01 ± 8.39. According to anxiety intensity, 57 (24.3%) persons were in normal range, 176 persons (74.9%) were in mild anxiety range and 2 persons (0.8%) had sever anxiety levels. There were a significant correlation between the mean score of internet anxiety and year of education and hours spent using internet (p=0.028, p=0.017). There was significant correlation between personality type and internet anxiety as well (p= 0.016).Conclusion: Based on this study internet anxiety was lower than moderate in dental school students and type A students who have characteristics like fast and quick, nervous and hottempered, biased life style, anxious, impatient and being competitive had more anxiety.Keywords: internet, dental student, Kerman, Personality type, anxiet

Discrete least squares meshless method for modeling 2D crack problems

In this paper, Discrete Least Squares meshless method (DLSM) is developed to analyze cracked structuresin an elastostatic problem. DLSMis a new really meshless method that does not use any mesh in computation. The method is based on the minimization of the least squares functional with respect to the nodal parameters. The least squares functional are formed as the weighted summation of the residual of the differential equation and its boundaryconditions. In thismethod, the domain of problem is discretized bysome nodesthat are used to produce Moving Least Squares shape functions. This type of discretization eliminates the Finite Element Method shortcomings. In this study, diffraction method was used to produce continuous shape functions around the crack. In diffraction method, the domain of influence wrap around the crack tip and it results in continuous derivatives of shape functions. Finally, the DLSM high efficiency and accuracy is presented by comparing the analytical results with numerical ones

Predictors of time to relapse in amphetamine-type substance users in the matrix treatment program in Iran : a Cox proportional hazard model application

Background: The aim of this study was to determine which predictors influence the risk of relapse among a cohort of amphetamine-type substance (ATS) users in Iran. Methods: A Cox proportional hazards model was conducted to determine factors associated with the relapse time in the Matrix treatment program provided by the Iranian National Center of Addiction Studies (INCAS) between March 2010 and October 2011. Results: Participating in more treatment sessions was associated with a lower probability of relapse. On the other hand, patients with less family support, longer dependence on ATS, and those with an experience of casual sex and a history of criminal offenses were more likely to relapse. Conclusion: This study broadens our understanding of factors influencing the risk of relapse in ATS use among an Iranian sample. The findings can guide practitioners during the treatment program

Preliminary survey of the scale insects fauna in Kermanshah, western Iran

Στην παρούσα εργασία έγινε προσπάθεια καταγραφής των κοκκοειδών εντόμων σε καλλιεργούμενα και μη φυτά στην περιοχή Kermanshah, στο δυτικό Ιράν, την περίοδο 2007 με 2009. Περισσότερα από 63 δείγματα συλλέχθηκαν από καλλιεργούμενα και μη φυτά. Τα είδη που αναγνωρίστηκαν ανήκουν στις οικογένειες: Diaspididae (12 είδη), Coccidae (7), Pseudococcidae (4), Margarodidae (3), Eriococcidae (2) και Ortheziidae (1). Η οικονομική σημασία ορισμένων ειδών συζητάται. Η εργασία είναι μέρος μεταπτυχιακής διατριβής που δεν έχει ολοκληρωθεί και αναμένονται και άλλα είδη να βρεθούν και να καταγραφούν μέχρι την ολοκλήρωσή της.The Coccoidea on cultivated and non-cultivated vegetation in Kermanshah, western Iran, were investigated between 2007 and 2009. More than 63 samples from cultivated and non-cultivated plants were collected. The identified species mainly belonged to the following families: Diaspididae (12 species), Coccidae (7), Pseudococcidae (4), Margarodidae (3), Eriococcidae (2) and Ortheziidae (1). The economically important species are discussed. This project is part of an MSc on Coccoidea studies which has still some time to run and so we expect that more species will be found in future