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Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Issue Info: 
  • Year: 

    1391
  • Volume: 

    12
  • Issue: 

    1
  • Pages: 

    269-280
Measures: 
  • Citations: 

    0
  • Views: 

    3942
  • Downloads: 

    0
Abstract: 

هدف اصلی در این مقاله حل معادلات انتگرال- دیفرانسیل فردهلم خطی با تاخیر زمانی از مراتب بالا است. روش مبتنی بر بسط لژاندر با استفاده از نقاط هم محلی گاوس- لژاندر می باشد. در این روش سری لژاندر قطع شده جواب معادله را در نظر گرفته و معادله انتگرال- دیفرانسیل خطی و شرایط داده شده را به یک معادله ماتریسی تبدیل می کنیم، سپس با استفاده از نقاط هم محلی گاوس- لژاندر، معادله ماتریسی تبدیل به یک دستگاه از معادلات جبری خطی با ضرایب مجهول بسط لژاندر می شود که از حل دستگاه، ضرایب بسط لژاندر تابع جواب به دست می آید. در آخر کارایی روش را با مثال هایی مورد تجزیه و تحلیل قرار می دهیم.

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

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Author(s): 

TAVASOLI H.

Issue Info: 
  • Year: 

    2012
  • Volume: 

    12
  • Issue: 

    1
  • Pages: 

    281-294
Measures: 
  • Citations: 

    0
  • Views: 

    1456
  • Downloads: 

    0
Abstract: 

Mortality forecasts are nowadays widely used to create and modify retirement pension schemes, disability insurance systems and other social security programmers. Experience shows that static life tables overestimate death probabilities. The reason for this overestimation is that static life tables, through being computed for a specific period of time, cannot take into account the decreasing mortality trend over time. Dynamic life tables overcome this problem by incorporating the influence of the calendar when graduating mortality.In this paper, we first apply the Lee-Carter model for estimation of mortality rate. Then, we use parametric and semi parametric bootstrap prediction intervals for mortality trend. Finally, these methods are applied for analysis of mortality data of Iran.

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

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    12
  • Issue: 

    1
  • Pages: 

    295-304
Measures: 
  • Citations: 

    0
  • Views: 

    2225
  • Downloads: 

    0
Abstract: 

Boundary value problems (BVPs) are one of the most important fields in engineering and mathematical physics. In self-adjoint case of these problems, there are some facilities to solve them, such as eigenvalues of adjoint equations are real numbers and associated eigenfunctions make an orthogonal basis system. In this paper a new method for investigation of self-adjoint B.V.Ps including ordinary differential equations (O.D.Es) is introduced. Based on this method, at first, some necessary conditions are obtained by making use of fundamental solutions of adjoint equations. Then an algebraic system is made by this necessary conditions and boundary conditions of given boundary value problem. Finally, by making use of Lagrangian identity and boundary values of unknown function, sufficient conditions for having a self-adjoint problem are presented.

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

View 2225

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    12
  • Issue: 

    1
  • Pages: 

    305-312
Measures: 
  • Citations: 

    0
  • Views: 

    1063
  • Downloads: 

    0
Abstract: 

Spatial generalized linear mixed models are usually used for modeling non-Gaussian and discrete spatial responses. In these models, spatial correlation of the data can be considered via latent variables. Estimation of the latent variables at the sampled locations, the model parameters and the prediction of the latent variables at un-sampled locations are of the most important interest in SGLMM. Often the normal assumption for latent variables is considered just for convenient in practice. Although this assumption simplifies the calculations, in practice, it is not necessarily true or possible to be tested. In this paper, a closed skew normal distribution is proposed for the spatial latent variables. This distribution includes the normal distribution and also remains closed under linear conditioning and marginalization. In these models, likelihood function cannot usually be given in a closed form and maximum likelihood estimations may be computationally prohibitive. In this paper, for maximum likelihood estimation of the model parameters and predictions of latent variables, an approximate algorithm is introduced that is faster than the former method. The performance of the proposed model and algorithm are illustrated through a simulation study.

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

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Issue Info: 
  • Year: 

    1391
  • Volume: 

    12
  • Issue: 

    1
  • Pages: 

    313-326
Measures: 
  • Citations: 

    0
  • Views: 

    949
  • Downloads: 

    0
Abstract: 

در این مقاله سه نوع از مسائل معکوس سهموی از نوع هدایت گرمایی و تشعشع گرمایی به روش تجزیه آدومیان بررسی می شود و برای حل این نوع مسائل معکوس از یک شرط فوق اضافی در یک نقطه داخلی ناحیه مفروض مساله استفاده می شود. این روش با سرعت همگرایی بالا، تقریب عددی از جواب دقیق مساله بدون نیاز به خطی سازی یا گسسته سازی می دهد. در واقع روش تجزیه آدومیان، نیاز به حل کردن هر سیستم خطی یا غیرخطی از معادلات جبری را از بین می برد. نتایج عددی به دست آمده از این روش حاکی از دقت و سرعت بالای این روش است .

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

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Author(s): 

MAHMOODI RISHAKANI AKBAR | |

Issue Info: 
  • Year: 

    2012
  • Volume: 

    12
  • Issue: 

    1
  • Pages: 

    327-338
Measures: 
  • Citations: 

    0
  • Views: 

    964
  • Downloads: 

    0
Abstract: 

Modular multiplication modulo a power of two is one of the operators that is used in cryptography specially symmetric cryptography. In this paper we investigate the statistical and algebraic properties of this operator from the cryptographic viewpoint. At first we compute the distribution of the output of modular multiplication modulo a power of two and the distribution of its component Boolean functions. Then after presenting a criterion for measuring the imbalance of maps, we obtain the imbalance of this operator and its component Boolean functions. At last we investigate the algebraic degree of the component Boolean functions of this operator and present a lower bound for the degree of these functions.

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

View 964

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Issue Info: 
  • Year: 

    1391
  • Volume: 

    12
  • Issue: 

    1
  • Pages: 

    339-354
Measures: 
  • Citations: 

    0
  • Views: 

    979
  • Downloads: 

    0
Abstract: 

بخش مهمی از مسائل قابل هدایت در مهندسی، از جمله مهندسی شیمی، مسائل کنترلی از نوع تنظیم کننده هستند. از طرفی روش های گرادیان مزدوج تعمیم یافته و روش نشاندن قابلیت های توانمندی در حل این مسائل دارند. این مقاله با معرفی الگوریتم آنها برای حل مسائل کنترل بهینه، به مقایسه این دو شیوه کارا، از نظر تحلیلی و عددی خواهد پرداخت. همچنین چگونگی کاربرد آنها در محاسبه مسیر و کنترل بهینه یک مخزن هم زده شده پیوسته راکتور شیمیایی را که تا کنون از این دو شیوه حل نشده اند، بیان و بررسی می نماید. در این راستا با بیان مثال های عددی، مقادیر بهینه همراه با مسیر و کنترل بهینه حاصل از این روش ها، مقایسه خواهند شد.

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

View 979

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