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Issue Info: 
  • Year: 

    2007
  • Volume: 

    25
  • Issue: 

    1
  • Pages: 

    73-80
Measures: 
  • Citations: 

    0
  • Views: 

    941
  • Downloads: 

    0
Abstract: 

Background: In spite of many advantages in Lenke classification of adolescent idiopathic scoliosis, the latest study of Richards et al showed that the King classification is better than had been reported recently and the Lenke classification System of adolescent idiopathic scoliosis is less reliable than previously reported.Methods: In this study, we performed a multi-surgeon comparison of these two classification Systems. After teaching and discussing all available data of these classification Systems with four spine surgeons, a pilot classification was performed. Then, they independently evaluated preoperative radiographs (standing posteroanterior, lateral, and two supine side-bending views) of 99 patients with adolescent idiopathic scoliosis. The results were determined by calculating the average percentage of intraobserver and interobserver agreement. reliability was quantified using kappa statistics.Findings: The King classification demonstrated good intraobserver and interobserver reliability, with an intraobserver agreement of 85.8% (kappa coefficient, 0.80). Interobserver percentage of agreement averaged 80.8% (kappa coefficient, 0.74). The complete Lenke classification, combining curve type, lumbar modifier, and sagittal thoracic modifier, demonstrated good reliability for both intraobserver and interobserver measurements. The intraobserver percentage of agreement averaged 85.8% (kappa coefficient, 0.82). The interobserver percentage of agreement averaged 80.8% (kappa coefficient, 0.77).Conclusion: In this study, with each investigator performing the radiographic measurements, the King and Lenke classifications were almost similar (the Lenke classification had slightly better results). Such better results might be due to more training of this complex classification System. So, because of greater coverage of idiopathic scoliosis curve and usefulness of Lenke classification System, we prefer using this classification System in our center.

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Issue Info: 
  • Year: 

    1386
  • Volume: 

    1
Measures: 
  • Views: 

    1984
  • Downloads: 

    0
Abstract: 

سازمان بین المللی استاندارد از زمان تاسیس خود در سال 1942، استانداردهای بین المللی متعددی را با همکار ی متخصصان و کارشناسان برجسته جهان و همچنین کارشناسان موسسه های استاندارد کشورهای عضو این سازمان، تدوین و منتشر نموده است. هر کدام از استانداردهای انتشار یافته حیطه خاصی از عملیات و فعالیتها را پوشش داده و بر روی آن متمرکز می شود. مانند استانداردهای سیستم کیفیت، ایمنی و بهداشت حرفه ای و مدیریت محیط زیست. با وجود تشابه فراوان بین این سیستم ها، ادغام نیازمندیهای این سه سیستم بدون پیچیدگی به نظر می رسد؛ ولی این امر در عمل به سادگی میسر نیست. چرا که بایستی ابتدا برای هر سازمان فایده ها، مشکلات و مسایل حاشیه ای جهت ادغام در نظر گرفته شود. علاوه بر این، در نظر داشتن وجوه اشتراک و تفاو تها بین سیستم های مورد نظر نیز ضروری است. با این حال اگر نیازمندیهای سیستم مدیریتی مورد نظر به درستی در سازمان طرح ریزی و اجرا شده باشد و کارکنان سازمان نیز آگاهی و تعهد لازم را در ارتباط با نیازمندیهای آن داشته باشند، ادغام سیستم های مدیریتی به راحتی و بدون ایجاد اختلال در روند جاری فعالیتهای سازمان امکان پذیر خواهد بود. در این مقاله پس از بحث و توضیح پیرامون استانداردهای کیفیت، مدیریت محیط زیست و ایمنی و بهداشت حرفه ای، روشهای ادغام این سه سیستم و فواید ناشی از این ادغام عنوان خواهد شد.

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Issue Info: 
  • Year: 

    2024
  • Volume: 

    56
  • Issue: 

    2
  • Pages: 

    291-304
Measures: 
  • Citations: 

    0
  • Views: 

    11
  • Downloads: 

    0
Abstract: 

The operation of protection Systems has a considerable impact on power System reliability. The main reason for cascading outages is protection System misoperation. Protection Systems affect power System reliability from two perspectives: First, incorrect operation of the protection System due to the failure of any of its components that causes failure to operate or undesired tripping. Second is the incorrect operation of the protection System due to the incorrect setting of relays. In the second case, the protection System is healthy, and incorrect operation is only the result of the erroneous setting of relays. In this paper, an analysis of power System reliability regarding failure and incorrect settings of the protection System is paid. This paper proposes an eight-state Markov model for a transmission line and its protection System incorporating protection System miscoordination distingue from failure to operate and undesired trip. The situation of network lines in the period of simulation time has been determined by the sequential Monte Carlo method, and the reliability indices such as Loss of Load Probability (LOLP), Loss of Load Expectation (LOLE), Expected Energy Not Supplied (EENS), and Expected Frequency of Load Curtailment (EFLC) are calculated. The proposed model is applied to a 6-bus IEEE RBTS network, and the reliability indices are calculated and compared from both perspectives to show the importance of the proposed model.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

SINGH C.J. | JAIN M.

Issue Info: 
  • Year: 

    2000
  • Volume: 

    13
  • Issue: 

    4
  • Pages: 

    17-22
Measures: 
  • Citations: 

    0
  • Views: 

    332
  • Downloads: 

    132
Abstract: 

This investigation deals with transient analysis of cold standby System with n units. Chapman-Kolmogorov equations are developed for repair facility with two repairmen and solved by using matrix technique. Availability and reliability factors have been obtained with probability of the System. A particular case has also been discussed.

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Journal: 

VIRTUAL

Issue Info: 
  • Year: 

    621
  • Volume: 

    1
  • Issue: 

    1
  • Pages: 

    49-64
Measures: 
  • Citations: 

    0
  • Views: 

    69
  • Downloads: 

    0
Abstract: 

In this paper, a Multivariate-Multistage Quality Control (MVMSQC) procedure is investigated, hi this procedure discriminate analysis, linear regression and control chart theory are combined to control the means of correlated characteristics of a process, which involves several serial stages. Furthermore, the quality of the output at each stage depends on the output of the previous stage as well as the process of the current stage. The theoretical aspects and the applications of this procedure are enhanced and clarified and its performance is evaluated through a series of simulated data. Both in-control (type one error) and out-of-control (type two error) Average Run Length (ARL) studies are made and the performance of the MVMSQC methodology is discussed.

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Issue Info: 
  • Year: 

    2001
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    97-108
Measures: 
  • Citations: 

    1
  • Views: 

    118
  • Downloads: 

    0
Keywords: 
Abstract: 

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Author(s): 

Palizi S. | Toufigh V.

Issue Info: 
  • Year: 

    2022
  • Volume: 

    38
  • Issue: 

    3-1
  • Pages: 

    89-100
Measures: 
  • Citations: 

    0
  • Views: 

    92
  • Downloads: 

    32
Abstract: 

Wood is one of the oldest materials that has always been known as a construction material. Despite its widespread application and unique properties, it has weaknesses such as relatively brittle behavior, especially in bending. In order to improve its performance and boost its features or strengthen wooden structural members, one solution is to employ FRP component, which is widely used as a rehabilitation tool. The lightness and ease of application for different materials such as concrete, wood, and steel have made it possible to increase the strength and ductility of structural elements. In this study, the few models that were available for the wood-FRP System were collected, and the uncertainty of six variables, as the most effective parameters in the strength of this System, was selected for reliability analysis. Also, during the steps, three live to dead load ratios equal to 0.75, 1, and 1.25 were assumed as the design loads. What was achieved during this research was that during the design process of wood-FRP, uncertainties had a significant impact on the reliability of existing models. Some models could be reliable enough to be applied for design purposes; however, uncertainties seriously affect the reliability of some models. Accordingly, the average reliability index of all six available models decreased from 4.88 in case one fails to consider uncertainties to 2.71 with uncertainties of the models. Among the five existing models presented in previous studies, the Palizi and Toufigh model with an average reliability index of 3.61 was the best-proposed model, which is in good agreement with the acceptable index of existing structural design criteria. It is worth noting that various variables affect the reliability of this System. However, in this study, only the uncertainty of the six variables of modulus of elasticity, thickness, length, and width of FRP, along with wood width and its compressive strength, was considered. Other sources of uncertainties may be considered while analyzing this System in future studies.

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Writer: 

رضائی مهدی

Issue Info: 
  • Year: 

    1394
  • Volume: 

    1
Measures: 
  • Views: 

    349
  • Downloads: 

    0
Abstract: 

لطفا برای مشاهده چکیده به متن کامل (PDF) مراجعه فرمایید.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    12
  • Issue: 

    47
  • Pages: 

    145-165
Measures: 
  • Citations: 

    0
  • Views: 

    175
  • Downloads: 

    40
Abstract: 

The Big Five Inventory (BFI) is one of the most widely used personality questionnaires, but very few studies have been conducted on its psychometric properties in Iranian population. This study was carried out with the aim of studying the psychometric properties of the BFI questionnaire. For this purpose, 390 university students in Tehran (210 girls and 180 boys) with an age range of 18 to 56 years (M = 27.52; SD = 8.79) were selected using the convenience sampling method and completed BFI and NEO-FFI questionnaires. Cronbach's alpha, multitrait-multimethod matrix, and confirmatory factor analysis were used to estimate the psychometric properties of the questionnaire. The result of the confirmatory factor analysis showed that 15 of the 44 items did not have a strong factor loading (higher than 0.40) on the corresponding factors and were therefore removed from the questionnaire. The fit indices showed that the Persian version of 29 questions (BFI-29) with 5 factors has a good fit with the data. The reliability analysis also showed that the range of Cronbach's alpha coefficients of the factors is from 0.70 to 0.79. The lowest Cronbach's alpha coefficient was related to agreeableness factor and the highest was related to conscientiousness. The findings from the multitrait-multimethod matrix showed that the BFI-29 questionnaire has good convergent and divergent validity with the NEO-FFI questionnaire. In general, based on the results of the present study, it can be said that the BFI-29 questionnaire has desirable psychometric properties and whenever a short tool for personality measurement is needed, this questionnaire can be used.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    12
  • Issue: 

    2
  • Pages: 

    87-98
Measures: 
  • Citations: 

    0
  • Views: 

    2463
  • Downloads: 

    0
Abstract: 

Bayesian Networks (BNs) as a strong framework for handling probabilistic events have been successfully applied in a variety of real-world problems, but they have received little attention in the area of composite power Systems reliability assessment. reliability assessment by BN provides some additional capabilities in comparison to conventional methods, both at the modeling and at the analysis levels. At the modeling level, several restrictive assumptions, implicit in the conventional methods, can be removed. At the analysis level, a variety of applicable reliability-based analysis which is hardly achievable in conventional methods, can be conveniently performed. This paper proposes a methodology based on Minimal Cutsets (MCs) to apply BNs to composite power System reliability modeling, reliability assessment and reliability-based analysis.To have a more accurate BN model, a new method of MC determination for composite power System is proposed. Bayesian structure is extracted, based on the determined MCs. Bayesian parameters are defined based on the logical relationships of nodes. To make the proposed method applicable to large composite power Systems, virtual nodes are proposed and combined with Bayesian model. Also, a variety of reliability-based analyses are presented which are hardly achievable in conventional methods. The proposed method is validated by applying to RBTS and comparing the results with other reliability analysis methods. The proposed methodology is applied to the reliability Test System (RTS), to show its feasibility in large networks.

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