The Effect of Milling and Thermal Annealing on Microstructural and Magnetic Properties of Nanocrystalline Fe and Fe-35 wt% Co Alloys

M. Delshad Chermahini,H. Shokrollahi,S. Sharafi,M. Zanderahimi 한국자기학회 2008 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Observer-Based Control Design for a Class of Nonlinear Systems Subject to Unknown Inputs

Saleh S. Delshad,Thomas Gustafsson,Hamid Reza Karimi,Ali Zemouche 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper deals with the problem of observer-based controller design for a class of nonlinear systems subject to unknown inputs. A novel method is presented to design a controller using estimated state variables which guarantees all the state variables of the closed-loop system converge to the vicinity of the origin and stay there forever. This is done via satisfying several sufficient conditions in terms of nonlinear matrix inequalities. In light of linear algebra, particularly matrix decompositions, the achieved conditions will be converted to a Linear Matrix Inequality (LMI) problem to facilitate the procedure of computing the observer and controller gains. Finally, the effectiveness of the proposed method is illustrated by implementing on a highly nonlinear chaotic system.

The effects of cluster pruning and the K:N ratio on greenhouse tomato yield and quality

Majid Fallah,Mojtaba Delshad,Hossein Sheikhi 한국원예학회 2021 Horticulture, Environment, and Biotechnology Vol.62 No.5

Both the number of fruit in a cluster and the K:N ratio in the nutrient solution can aff ect the yield and quality of greenhousegrowntomatoes ( Solanum lycopersicum L.). To prevent the loss of photoassimilates to fruit at the end of clusters, which rarelymature and ripen, it is necessary to know the optimal number of fruit in a cluster under diff erent nutritional conditions. In thisstudy, we investigated the eff ects of cluster pruning and the K:N ratio in the nutrient solution on yield, yield components, andquality of tomato fruit grown in a greenhouse. The treatments consisted of fi ve levels of cluster pruning (control or unpruned,and retaining 4, 6, 8, and 10 fruit per cluster), and two levels of the K:N ratio in the nutrient solution (2:1 and 4:1). Underboth K:N ratios, the unpruned and ten-fruit cluster treatments had the highest yield. These treatments also had the highestunripe fruit weight. The highest ripe fruit dimensions and weight were found in four-fruit clusters fed by the solution with aK:N ratio of 2:1. Fruit fi rmness was higher than in other treatments in four-fruit clusters when the K:N ratio was 4:1. Fruitharvested from the four-fruit cluster treatment had the highest titratable acidity compared to the other treatments, while theK:N ratio did not have a signifi cant eff ect on this trait. The highest total soluble solids were found in fruit obtained fromfour-fruit clusters grown with the 2:1 K:N solution. In general, we concluded that under our growing conditions, keepingten fruit in a cluster and adjusting the K:N ratio to 2:1 in the nutrient solution is advisable for the cultivar of cherry tomatoused in this study, although some fruit quality factors may be improved when the number of fruit in clusters is manipulated.

Effects of Salt Stress on Physiological and Postharvest Quality Characteristics of Different Iranian Genotypes of Basil

Farzaneh Bekhradi,Mojtaba Delshad,Alicia Marín,Maria C Luna,Yolanda Garrido,Abdolkarim Kashi,Mesbah Babalar,Maria I Gil 한국원예학회 2015 Horticulture, Environment, and Biotechnology Vol.56 No.6

This study examined the effects of salt stress on the physiological responses and postharvest quality characteristics of fresh sweet basil (Ocimum basilicum L.). Plants were treated with 40 and 80 mM NaCl for 25 days during cultivation in 2014. Two green genotypes, Green Iranian and Genovese basil, were studied after harvest, and while two Iranian genotypes, Green and Purple Iranian basil, were compared during storage. Yield and the stem length were significantly reduced under salt stress only in the two Iranian cultivars. Salinity significantly reduced leaf thickness and the area of parenchyma cells in both Green Iranian and Genovese basil. As salt concentration increased, transpiration and the content of chlorophylls decreased significantly while the lipid peroxidation increased in the Genovese genotype. During storage at 12°C, the respiration rate of salt-stressed leaves was similar to that of control leaves. The visual quality of Purple Iranian basil was better preserved during storage than the Green Iranian basil. However, salt stress positively affected the visual quality of Green Iranian basil, decreasing darkening and maintaining the quality above the limit of marketability after 7 days of storage. The total content of phenolic acids and anthocyanins did not show significant differences between growth conditions. However, during storage of Green Iranian basil, salt stress increased the content of individual and total phenolic acids compared to the control. To summarize, the positive or negative effects of salt stress on basil depend on the degree of tolerance of the different genotypes.

Effect of Grafting on Growth, Yield and Fruit Quality of Single and Double Stemmed Tomato Plants Grown Hydroponically

Amir Rahmatian,Mojtaba Delshad,Reza Salehi-Mohammadi 한국원예학회 2014 Horticulture, Environment, and Biotechnology Vol.55 No.2

Vegetative growth traits, and fruit yield and quality of ‘Synda’ tomato plants were compared with thosegrafted onto ‘King Kong’ rootstock or self-grafted. All experimental plants were trained to have either one stem(single stemmed) or two stems (double stemmed). Values of stem diameter, leaf area, leaf and root fresh weight (FW),and root dry matter (DM) increased with grafting onto ‘King Kong’. Stem length, stem and root FW, and stem DMin double stemmed plants increased. Mean fruit weight, number of fruits, and yield were significantly increased by11, 17.8, and 27%, respectively, in the grafted plants. Number of fruits and fruit yield increased, while mean fruitweight decreased by 12%, in double stemmed plants. Contents of total soluble solids (TSS) and vitamin C increasedin the fruits harvested from the grafted plants. Grafted and double stemmed plants resulted in significant increase indry matter allocation to different tomato organs.

A new lossless snubber for DC-DC converters with energy transfer capability

Shabnam Nasr Esfahani,Majid Delshad,Mohhamad Bagher Tavakoli 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.3

In this paper, a new passive lossless snubber circuit with energy transfer capability is proposed. The proposed lossless snubber circuit provides Zero-Current Switching (ZCS) condition for turn-on instants and Zero-Voltage Switching (ZVS) condition for turn-off instants. In addition, its diodes operate under soft switching condition. Therefore, no significant switching losses occur in the converter. Since the energy of the snubber circuit is transferred to the output, there are no significant conduction losses. The proposed snubber circuit can be applied on isolated and non-isolated converters. To verify the operation of the snubber circuit, a boost converter using the proposed snubber is implemented at 70W. Also, the measured conducted Efficiency Electromagnetic Interference (EMI) of the proposed boost converter and conventional ones are presented which show the effects of proposed snubber on EMI reduction. The experimental results confirm the presented theoretical analysis.

Design-Oriented Stress-Strain Model for FRP-Confined Lightweight Aggregate Concrete

Hooshang Dabbagh,Maysam Delshad,Kasra Amoorezaei 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.1

Despite the advantages of lightweight aggregate concrete (LWAC), its brittleness in compression has limited its vast application. Jacketing by fiber-reinforced polymer (FRP) tends to be one method to overcome this negative point. The current study attempted to recognize the FRP confinement impact on the LWAC compressive monotonic behavior. Both fine and coarse aggregates were Scoria aggregate. The variables include the type and number of FRP layers; 150 × 300 mm cylindrical specimens were wrapped with 1, 2, 3, and 4 layers of glass FRP (GFRP) and carbon FRP (CFRP) strips. An investigation was performed on the monotonic stress-strain curve belonging to LWAC confined with FRP, and key points, including ultimate stress and strain on the curve, were explored. The results revealed that the key points would significantly improve by increasing FRP layers. Although the influence of GFRP confinement on enhancing the ultimate strain appears to be more considerable than the CFRP confinement, CFRP jacketing of LWAC upgrades the ultimate strength to the higher level compared to wrapping with GFRP. Based on the interpretation of experimental results, a design-oriented stress-strain model was established to predict the monotonic compressive response of Scoria-LWAC circular specimens confined with CFRP and GFRP. The validity of the model was examined. The predicted output was appropriately in line with the experimental findings.

A new interleaved high step up converter with low voltage stress on the main switches

Babak Tohidi,Majid Delshad,Hadi Saghafi 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.4

In this paper, a new interleaved high step-up converter with low voltage stress on the switches is proposed. In the proposed converter, soft switching is provided for all switches by just one auxiliary switch, which decreases the conduction loss of auxiliary circuit. Also, the auxiliary circuit is expanded on the converter with more input branches. In the converter all main switches operate under zero voltage switching condition and auxiliary switch operate under zero current switching condition. Because of the interleaved structure, the reliability of converter increases and input current ripples decreases. The clamp capacitor in the converter not only absorb the voltage spikes across the switch due to leakage inductance, but also improve voltage gain. The proposed converter is fully analyzed and to verify the theoretical analysis, a 100 W prototype was implemented. Also, to show the effectiveness of auxiliary circuit on conduction EMI, EMI of the proposed converter comprised with hard switching counterpart.

Observer Design for a Class of Nonlinear Delayed Systems with Unknown Inputs and Markovian Jump Parameters

Amir Hossein Abolmasoumi,Saleh S. Delshad 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

The problem of full-order observer design for a class of delayed nonlinear systems with unknown inputs and Markovian jumping parameters is considered. The design method is formulated as solving a set of linear matrix inequalities (LMI’s). Extending the results of nonlinear observer design to Markovian jump systems with time-varying delays is the main advantages of this paper. The sufficient LMI conditions are dependent on both the upper and lower bounds of delay. The effectiveness of the proposed method is shown via an illustrative example.

Leaf Gas Exchanges and Mineral Ion Composition in Xylem Sap of Iranian Melon Affected by Rootstocks and Training Methods

Salehi, Reza,Kashi, Abdolkarim,Lee, Jung-Myung,Babalar, Mesbah,Delshad, Mojtaba,Lee, Sang-Gyu,Huh, Yun-Chan American Society for Horticultural Science 2010 HortScience Vol.45 No.5

<P>Photosynthetic characteristics, concentrations of mineral elements in xylem sap, and some vegetative traits of ‘Khatooni’ melon were compared with those of melons grafted onto three <I>Cucurbita</I> rootstocks cvs., Ace, Shintozwa, and ShintoHongto, and trained with three methods: T1) no pinching and fruit thinning; T2) pinched to produce two lateral branches; and T3) pinched to two branches and all the flowers and lateral branches from lower nodes thinned. Internal CO2 and water use efficiency varied with rootstocks. Stem diameter of scions, aerial fresh and dry weights, mean fruit weight and yield, electric conductivity, pH, and sap volume per plant of grafted plants were higher in grafted melons than in the nongrafted ones. These traits were unaffected by training methods. Mineral concentrations varied considerably depending on the rootstocks and training methods used. Xylem sap collected from the decapitated stem base of grafted melons trained with T2 and T3 methods contained a higher amount of mineral ions, especially NO3<SUP>−</SUP>, PO4<SUP>3−</SUP>, and K<SUP>+</SUP>, than did the sap from own-rooted plants. The increase in the mineral levels in sap resulting from grafting was most apparent in ‘Khatooni’ grafted onto ‘ShintoHongto’ rootstock.</P>