A mathematical steel panel zone model for flanged cruciform columns

Hamed Saffari,Sina Sarfarazi,Ali Fakhraddini 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.4

Cruciform sections are an appropriate option for columns of orthogonal moment resisting frames for equal bending strength and stiffness about two main axes and the implementation is easier for continuity plates. These columns consist of two I-shaped sections, so that one of them is cut out in middle and two generated T-shaped sections be welded into I-shaped profile. Furthermore, in steel moment frames, unbalance moment at the beamcolumn connection leads to shear deformation in panel zone. Most of the obtained relations for panel zone strength derived from experimental and analytical results are on I-shaped columns with almost thin flanges. In this paper, a parametric study has been carried out using Finite Element Method (FEM) with effective parameters at the panel zone behavior. These parameters consist of column flange thickness, column web thickness, and thickness of continuity plates. Additionally, a mathematical model has been suggested to determine strength of cruciform column panel zone and has been shown its accuracy and efficiency.

Soil Infiltration Characteristics in Alternate and Conventional Furrow Irrigation using Different Estimation Methods

Hamed Ebrahimian 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.6

Field data sets for seven irrigation events during maize growing season were collected for characterizing infiltration properties invariable Alternate, Fixed Alternate and Conventional Furrow Irrigation (AFI, FFI and CFI, respectively). Three various estimationmethods; the two-point method and the INFILT and IPARM models; were used to estimate the infiltration parameters of the modifiedKostiakov equation for alternate and conventional furrows and then compared with field results. Less runoff losses and largerinfiltration were observed in alternate furrows as compared to conventional furrows due to increased lateral water movement to nonirrigatedfurrow. AFI had somewhat greater infiltration rate than FFI. The steady infiltration rate in AFI and FFI was higher than inCFI. The IPARM model had the most accurate and reliable performance relative to others in three irrigation treatments. However thetwo-point method also performed well. The INFILT model was not suitable on the experimental field studied and highlyoverestimated the infiltration for all irrigation treatments. The results indicated that measuring both advance and runoff data isnecessary to achieve reasonable and precise infiltration parameters. Having different infiltration characteristics in alternate furrows,design variables of alternate furrow irrigation will be different from conventional furrow irrigation in the same field.

Radiolucent rim as a possible diagnostic aid for differentiating jaw lesions

Hamed Mortazavi,Maryam Baharvand,Somayeh Rahmani,Soudeh Jafari,Parvin Parvaei 대한영상치의학회 2015 Imaging Science in Dentistry Vol.45 No.4

In this study, we formulate a new proposal that complements previous classifications in order to assist dental practitioners in performing a differential diagnosis based on patients’ radiographs. We used general search engines and specialized databases such as Google Scholar, PubMed, PubMed Central, MedLine Plus, Science Direct, Scopus, and well-recognized textbooks to find relevant studies by using keywords such as “jaw disease,” “jaw lesions,” “radiolucent rim,” “radiolucent border,” and “radiolucent halo.” More than 200 articles were found, of which 70 were broadly relevant to the topic. We ultimately included 50 articles that were closely related to the topic of interest. When the relevant data were compiled, the following eight lesions were identified as having a radiolucent rim: periapical cemento-osseous dysplasia, focal cemento-osseous dysplasia, florid cemento-osseous dysplasia, cemento-ossifying fibroma, osteoid osteoma, osteoblastoma, odontoma, and cementoblastoma. We propose a novel subcategory, jaw lesions with a radiolucent rim, which includes eight entities. The implementation of this new category can help improve the diagnoses that dental practitioners make based on patients’ radiographs.

A 12 bit 750 kS/s 0.13 mW Dual-sampling SAR ADC

Hamed Abbasizadeh,Dong-Soo Lee,Sang-Sun Yoo,Joon-Tae Kim,Kang-Yoon Lee 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.6

A 12-bit 750 kS/s Dual-Sampling Successive Approximation Register Analog-to-Digital Converter (SAR ADC) technique with reduced Capacitive DAC (CDAC) is presented in this paper. By adopting the Adaptive Power Control (APC) technique for the two-stage latched type comparator and using bootstrap switch, power consumption can be reduced and overall system efficiency can be optimized. Bootstrapped switches also are used to enhance the sampling linearity at a high input frequency. The proposed SAR ADC reduces the average switching energy compared with conventional SAR ADC by adopting reduced the Most Significant Bit (MSB) cycling step with Dual-Sampling of the analog signal. This technique holds the signal at both comparator input asymmetrically in sample mode. Therefore, the MSB can be calculated without consuming any switching energy. The prototype SAR ADC was implemented in 0.18-μm CMOS technology and occupies 0.728 mm2. The measurement results show the proposed ADC achieves an Effective Number-of-Bits (ENOB) of 10.73 at a sampling frequency of 750 kS/s and clock frequency of 25 MHz. It consumes only 0.13 mW from a 5.0-V supply and achieves the INL and DNL of +2.78/-2.45 LSB and +0.36/-0.73 LSB respectively, SINAD of 66.35 dB, and a Figures-of-Merit (FoM) of a 102 fJ/conversion-step.

Distributed Series Elastic Actuator

Hamed Ali Yaghini Bonabi,Majid Nili Ahmadabadi,Fariba Bahrami 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

Series elastic actuators (SEA’s) have been widely used in rehabilitation robots and haptic devices to provide sufficient compliance as well as safety, among some other properties, for performing interactive tasks. Nevertheless, SEA"s suffer from two major drawbacks; namely short bandwidth and limited rendered stiffness. In this paper, we propose a new elastic actuator concept in that a set of spatially distributed and mechanically parallel SEAs, each called a SEA component, are grouped and control a single joint. We call our system distributed series elastic actuator (DSEA). Each SEA component has its own controller but gets its set point from a load distribution system. The analytical and the simulation results show that a DSEA has wider bandwidth and better transient performance in addition to elevated rendered stiffness in comparison to its equivalent SEA. In addition, DSEAs consume less energy and require lower power as well as torque.

An experimental study on the effect of a novel nature-inspired 3D-serrated leading edge on the aerodynamic performance of a double delta wing in the transitional flow regime

Hamed Khodabakhshian Naeini,Mahdi Nili-Ahmadabadi,김경천 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12

This study examines the effect of nature-inspired leading edge 3D serration on the aerodynamic performance of a 65/35-degree double delta wing. Force measurement experiments were conducted on a smooth-surface model and a model equipped with various combinations of serrated pieces in the leading edge area. Four symmetric different positions were examined in a low-speed wind tunnel. The transitional flow regime was applied with Reynolds numbers of 2×10 5 and angles of attack (AOA) of 0 to 36 degrees. Compared to the clean model, there is a notable enhancement in the maximum lift coefficient, especially for the pieces located at the apex and kink angle locations. However, when changing the combination of serrated leading edge (SLE) elements, a decline in C L can be seen at some AOAs, and adding more SLE pieces is not always useful. A drag reduction is also achieved by installing these elements, which provided a higher lift-to-drag ratio for all AOAs. Finally, the serrated leading edge postponed the stall angle of the double delta wing.

The Effect of Strategic Orientation on Market Performance: Study of the Mediators

Hamed Rahimpour Langroudi,Moslem Sharifi,Hossein Rahimpour Langroudi 한국유통과학회 2019 The Journal of Industrial Distribution & Business( Vol.10 No.4

Purpose - This study investigates the effect of strategic orientation on market performance with emphasis on the mediative role of innovation capability, economic value and relational value in food producer companies. Research design, data, and methodology – In this descriptive study, a population of 244 managers and employees of Food industry companies in Tehran were investigated. The respondents filled a questionnaire on strategic orientation, innovation capability, economic value, relational value and market performance, during January to August 2018. Reliability and validity were evaluated by Cronbach’s alpha coefficient and confirmatory factor analysis. To analyze the data, Spearman's correlation coefficient and structural equation modeling were used by SmartPLS software. Results - Effects of competitor’s orientation and technology orientation on all three intermediary variables were positive and significant. The effect of customer orientation on innovation and economic value was positive and significant, but the effect of customer orientation on the value of the relationship was insignificant. Furthermore, entrepreneurial orientation has a positive and significant effect on innovation capability. The effects of three mediator variables on market performance are positive and significant. Conclusions - As the relationship between the mediator variables and market performance were positive and significant, companies should have a comprehensive plan of focus on strengthening these variables.

Stable Assist-as-Needed Controller Design for a Planar Cable-Driven Robotic System

Hamed Jabbari Asl,윤정원 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.6

Robot-assisted rehabilitation systems have shown promising advantages over traditional therapist-basedmethods. The type of the controller has an important role in the efficiency of such systems. In this regard, thispaper presents a new assist-as-needed (AAN) controller for 4-cable planar robots. The main purpose is to designa bounded-input AAN controller with an adjustable assistance level and a guaranteed closed-loop stability. Theproposed controller involves the advantages of both the model-based and non-model-based AAN controllers, and inthis way can increase the efficiency of rehabilitation. The controller aims to follow a desired trajectory by allowingan adjustable tracking error, which enables the human subject to freely move the target limb inside this error area. This feature of the controller gives an important advantage over the existing model-based controllers. The controlleralso compensates for the dynamic modeling uncertainties of the system through an adaptive neural network. Theadaptive term includes a forgetting factor to adjust the assistance level of neural network term. The stability of theclosed-loop system is analysed, and the uniformly ultimately bounded stability is proven. The effectiveness of theproposed control scheme is validated through simulations conducted for gait rehabilitation.

Primary Analysis of Information Distribution at Walkbase Company: Developing an Information Strategy

Hamed Ahmadinia,Muhaimin Karim,Edward Ofori 한국유통과학회 2015 The Journal of Industrial Distribution & Business( Vol.6 No.4

Purpose Currently, organizations – must have a plan to achieve their future objectives. In this case, an information strategy facilitates greater success when planning for the future in any organization. Research design, data, and methodology – The core objective of the project was to explore the information infrastructure of Walkbase in a discursive manner. We started the project by providing a description of the firm, which facilitates retail outlets using in-store analytical devices. Results – We conclude that the management of Walkbase revised its current information structure to implement a more structured one that might be included in a long-term investment. On such an occasion, management can prioritize the component to develop first. Conclusions – Along with our results, we also described the business, its products, its facilities, and how it can serve different industries. Finally, we left the prioritization decision within the framework’s components to top management.

Grain Growth in Nanocrystalline Iron and Fe-Al Alloys

Hamed Mirzadeh,Amir Zomorodian 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.1

The effects of the annealing temperature and time, cryomilling in liquid nitrogen, and the addition of aluminum powder on the thermal stability and grain growth behavior of nanocrystalline iron were modeled using the Artificial Neural Network (ANN) technique. The developed model can be used as a guide for the quantification of the grain growth by considering the effects of annealing temperature and time. The model also quantified the effect of Al on the thermal stability of cryomilled nanocrystalline Fe. The model results showed that the cryomilling of Fe has a tangible effect on the stabilization of the nanostructure.