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ON THE CLOSED RANGE COMPOSITION AND WEIGHTED COMPOSITION OPERATORS
Keshavarzi, Hamzeh,Khani-Robati, Bahram Korean Mathematical Society 2020 대한수학회논문집 Vol.35 No.1
Let ψ be an analytic function on 𝔻, the unit disc in the complex plane, and φ be an analytic self-map of 𝔻. Let 𝓑 be a Banach space of functions analytic on 𝔻. The weighted composition operator W<sub>φ,ψ</sub> on 𝓑 is defined as W<sub>φ,ψ</sub>f = ψf ◦ φ, and the composition operator C<sub>φ</sub> defined by C<sub>φ</sub>f = f ◦ φ for f ∈ 𝓑. Consider α > -1 and 1 ≤ p < ∞. In this paper, we prove that if φ ∈ H<sup>∞</sup>(𝔻), then C<sub>φ</sub> has closed range on any weighted Dirichlet space 𝒟<sub>α</sub> if and only if φ(𝔻) satisfies the reverse Carleson condition. Also, we investigate the closed rangeness of weighted composition operators on the weighted Bergman space A<sup>p</sup><sub>α</sub>.
( Amin Keshavarzi ),( Abolfazl Toroghi Haghighat ),( Mahdi Bohlouli ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.9
The fact that cloud computing services have been proposed in recent years, organizations and individuals face with various challenges and problems such as how to migrate applications and software platforms into cloud or how to ensure security of migrated applications. This study reviews the current challenges and open issues in cloud computing, with the focus on autonomic resource management especially in federated clouds. In addition, this study provides recommendations and research roadmaps for scientific activities, as well as potential improvements in federated cloud computing. This survey study covers results achieved through 190 literatures including books, journal and conference papers, industrial reports, forums, and project reports. A solution is proposed for autonomic resource management in the federated clouds, using machine learning and statistical analysis in order to provide better and efficient resource management.
Fatigue Performance Analysis of Pavements with RAP Using Viscoelastic Continuum Damage Theory
Yizhuang David Wang,Behrooz Keshavarzi,Youngsoo Richard Kim 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.6
This paper presents the results of a study to evaluate the fatigue performance of pavements that contain RAP materials. The studyis based on two different accelerated loading tests conducted in the United States. Each of these two projects has correspondingpavements with and without RAP mixtures that were constructed over the same aggregate base and subgrade and subjected to thesame traffic loading and environmental conditions. The primary reason for selecting these two projects is that they exhibited oppositetrends in a comparison of the fatigue cracking performance of their pavements with and without RAP. The asphalt mixtures in the testpavements were characterized using the simplified viscoelastic continuum damage model. The fatigue cracking performance of thepavements was then modeled using the characterized material properties, in situ pavement structures and traffic loads, and climateconditions in FlexPAVE™, a three-dimensional layered viscoelastic finite element program with moving load analysis. The resultantfatigue cracking performance predictions matched the field observations well. Both the simulation results and the field observationsalso showed that the fatigue cracking performance of the asphalt mixtures that contained RAP materials differed according topavement structure and the fatigue cracking-resistant quality of the RAP mixtures.
Zare, Rezvan,Choobineh, Alireza,Keshavarzi, Sareh Occupational Safety and Health Research Institute 2017 Safety and health at work Vol.8 No.3
Background: The present study was carried out to assess the relationship between sickness absence and occupational stress, sleep quality, and amplitude and stability of circadian rhythm as well as to determine contributing factors of sickness absence. Methods: This cross sectional study was conducted on 400 randomly selected employees of an Iranian gas company. The data were collected using Pittsburgh sleep quality index, Karolinska sleepiness scale, circadian type inventory, and Osipow occupational stress questionnaires. Results: The mean age and job tenure of the participants were $33.18{\pm}5.64years$ and $6.06{\pm}4.99years$, respectively. Also, the participants had been absent from work on average 2.16 days a year. According to the results, 209 participants had no absences, 129 participants had short-term absences, and 62 participants had long-term absences. The results showed a significant relationship between short-term absenteeism and amplitude of circadian rhythm [odds ratio (OR) = 6.13], sleep quality (OR = 14.46), sleepiness (OR = 2.08), role boundary (OR = 6.45), and responsibility (OR = 5.23). Long-term absenteeism was also significantly associated with amplitude of circadian rhythm (OR = 2.42), sleep quality (OR = 21.56), sleepiness (OR = 6.44), role overload (OR = 4.84), role boundary (OR = 4.27), and responsibility (OR = 3.72). Conclusion: The results revealed that poor sleep quality, amplitude of circadian rhythm, and occupational stress were the contributing factors for sickness absence in the study population.
Saberhosseini, Seyed Erfan,Keshavarzi, Reza,Ahangari, Kaveh Techno-Press 2014 Geomechanics & engineering Vol.7 No.3
Estimation of fracture initiation pressure is one of the most difficult technical challenges in hydraulic fracturing treatment of vertical or horizontal oil wells. In this study, the influence of in-situ stresses and pore pressure values on fracture initiation pressure and its profile in vertical and horizontal oil wells in a normal stress regime have been investigated. Cohesive elements with traction-separation law (XFEM-based cohesive law) are used for simulating the fracturing process in a fluid-solid coupling finite element model. The maximum nominal stress criterion is selected for initiation of damage in the cohesive elements. The stress intensity factors are verified for both XFEM-based cohesive law and analytical solution to show the validation of the cohesive law in fracture modeling where the compared results are in a very good agreement with less than 1% error. The results showed that, generally by increasing the difference between the maximum and minimum horizontal stress, the fracture pressure and its profile has been strongly changed in the vertical wells. Also, it's been clearly observed that in a horizontal well drilled in the direction of minimum horizontal stress, the values of fracture pressure have been significantly affected by the difference between overburden pressure and maximum horizontal stress. Additionally, increasing pore pressure from under-pressure regime to over-pressure state has made a considerable fall on fracture pressure in both vertical and horizontal oil wells.
Human Error Analysis in a Permit to Work System: A Case Study in a Chemical Plant
Mehdi Jahangiri,Naser Hoboubi,Akbar Rostamabadi,Sareh Keshavarzi,Ali Akbar Hosseini 한국산업안전보건공단 산업안전보건연구원 2016 Safety and health at work Vol.7 No.1
Background: A permit to work (PTW) is a formal written system to control certain types of work which are identified as potentially hazardous. However, human error in PTW processes can lead to an accident. Methods: This cross-sectional, descriptive study was conducted to estimate the probability of human errors in PTWprocesses in a chemical plant in Iran. In the first stage, through interviewing the personnel and studying the procedure in the plant, the PTW process was analyzed using the hierarchical task analysis technique. In doing so, PTWwas considered as a goal and detailed tasks to achieve the goal were analyzed. In the next step, the standardized plant analysis risk-human (SPAR-H) reliability analysis method was applied for estimation of human error probability. Results: The mean probability of human error in the PTW system was estimated to be 0.11. The highest probability of human error in the PTW process was related to flammable gas testing (50.7%). Conclusion: The SPAR-H method applied in this study could analyze and quantify the potential human errors and extract the required measures for reducing the error probabilities in PTW system. Some suggestions to reduce the likelihood of errors, especially in the field of modifying the performance shaping factors and dependencies among tasks are provided.
Human Error Analysis in a Permit to Work System: A Case Study in a Chemical Plant
Jahangiri, Mehdi,Hoboubi, Naser,Rostamabadi, Akbar,Keshavarzi, Sareh,Hosseini, Ali Akbar Occupational Safety and Health Research Institute 2016 Safety and health at work Vol.7 No.1
Background: A permit to work (PTW) is a formal written system to control certain types of work which are identified as potentially hazardous. However, human error in PTW processes can lead to an accident. Methods: This cross-sectional, descriptive study was conducted to estimate the probability of human errors in PTWprocesses in a chemical plant in Iran. In the first stage, through interviewing the personnel and studying the procedure in the plant, the PTW process was analyzed using the hierarchical task analysis technique. In doing so, PTWwas considered as a goal and detailed tasks to achieve the goal were analyzed. In the next step, the standardized plant analysis risk-human (SPAR-H) reliability analysis method was applied for estimation of human error probability. Results: The mean probability of human error in the PTW system was estimated to be 0.11. The highest probability of human error in the PTW process was related to flammable gas testing (50.7%). Conclusion: The SPAR-H method applied in this study could analyze and quantify the potential human errors and extract the required measures for reducing the error probabilities in PTW system. Some suggestions to reduce the likelihood of errors, especially in the field of modifying the performance shaping factors and dependencies among tasks are provided.
Accuracy of Endoscopic Ultrasonography for Determination of Tumor Invasion Depth in Gastric Cancer
Razavi, Seyed Mohsen,Khodadost, Mahmoud,Sohrabi, Masoudreza,Keshavarzi, Azam,Zamani, Farhad,Rakhshani, Naser,Ameli, Mitra,Sadeghi, Reza,Hatami, Khadijeh,Ajdarkosh, Hossein,Golmahi, Zeynab,Ranjbaran, M Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.8
Background: Gastric cancer (GC) is one the common lethal cancers in Iran. Detection of GC in the early stages would assesses to improve the survival of patients. In this study, we attempt to evaluate the accuracy of EUS in detection depth of invasion of GC among Iranian Patients. Materials and Methods: This study is a retrospective study of patients with pathologically confirmed GC. They underwent EUS before initiating the treatment. The accuracy of EUS and agreement between the two methods was evaluated by comparing pre treatment EUS finding with post operative histopathological results. Results: The overall accuracy of EUS for T and N staging was 67.9% and 75.47, respectively. Underestimation and overestimation was seen in 22 (14.2%) and 40 (25.6%) respectively. The EUS was more accurate in large tumors and the tumors located in the middle and lower parts of the stomach. The EUS was more sensitive in T3 staging. The values of weighted Kappa from the T and N staging were 0.53 and 0.66, respectively. Conclusions: EUS is a useful modality for evaluating the depth of invasion of GC. The accuracy of EUS was higher if the tumor was located in the lower parts of the stomach and the size of the tumor was more than 3 cm. Therefore, judgments made upon other criteria evaluated in this study need to be reconsidered.