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نویسندگان: 

Rafiee A. | Moradi P. | Ghaderzadeh A.

اطلاعات دوره: 
  • سال: 

    1400
  • دوره: 

    51
  • شماره: 

    4
  • صفحات: 

    443-454
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    187
  • دانلود: 

    37
چکیده: 

Multi-label classification aims at assigning more than one label to each instance. Many real-world multi-label classification tasks are high dimensional, leading to reduced performance of traditional classifiers. Feature selection is a common approach to tackle this issue by choosing prominent features. Multi-label feature selection is an NP-hard approach, and so far, some swarm intelligence-based strategies and have been proposed to find a near optimal solution within a reasonable time. In this paper, a hybrid intelligence algorithm based on the binary algorithm of particle swarm optimization and a novel Local search strategy has been proposed to select a set of prominent features. To this aim, features are divided into two categories based on the extension rate and the relationship between the output and the Local search strategy to increase the convergence speed. The first group features have more similarity to class and less similarity to other features, and the second is redundant and less relevant features. Accordingly, a Local operator is added to the particle swarm optimization algorithm to reduce redundant features and keep relevant ones among each solution. The aim of this operator leads to enhance the convergence speed of the proposed algorithm compared to other algorithms presented in this field. Evaluation of the proposed solution and the proposed statistical test shows that the proposed approach improves different classification criteria of multi-label classification and outperforms other Methods in most cases. Also in cases where achieving higher accuracy is more important than time, it is more appropriate to use this Method.

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اطلاعات دوره: 
  • سال: 

    1383
  • دوره: 

    12
  • شماره: 

    23
  • صفحات: 

    32-37
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    1255
  • دانلود: 

    170
چکیده: 

مقدمه: حرکت بیمار در حین انجام اسپکت قلب میتواند باعث ایجاد نقائص کاذب در اسکن بیمار گردد. تاثیر روش های مختلف بازسازی تصویر بر روی این آرتفکت ها بررسی نشده است. تعیین ارتباط شدت و محل حرکت و یا مدت زمان آن با نقائص ایجاد شده می تواند در بررسی این نقائص کاذب و همچنین در طراحی نرم افزارهای تصحیح حرکت کمک کننده باشد. مطالعه حاضر یک مطالعه اولیه برای بررسی این نقائص در روشهای مختلف بازسازی می باشد. مواد و روش ها: اسپکت پرفیوژن قلب طبیعی از یک خانم با احتمال کم از بیماری عروق کرونری که در بررسی توسط سه متخصص پزشکی هسته ای هیچگونه حرکتی در زمان تصویر برداری نداشت و در 32 نمای 30 ثانیه ای در 180 درجه تصویر برداری شده بود مورد بررسی قرار گرفت. جابجائی اسکن اولیه در نماهای 7؛ 16 و 24 (به عنوان نواحی ابتدائی- وسط و انتهائی تصویر برداری) و با شدت های یک، دو و سه پیکسل و همچنین به مدت زمان 30 تا 90 ثانیه توسط نرم افزار Vision صورت گرفت. همچنین جابجائی اسکن در محورهایX وY و در جهات مثبت و منفی انجام گردید. جابجائی ها به دو صورت برگشت پذیر و برگشت ناپذیر انجام گرفت و مجموعا 144 اسکن جدید ایجاد شد که با دو روشIterative  نوعOrdered Subset Expectation Maximization (OSEM) وFiltered Back Projection (FBP) بازسازی شدند (288 تصویر) و مورد تفسیر نیمه کمی قرار گرفتند. یافته ها: در جابجائی های به میزان یک، دو و سه پیکسل نسبت اسکن های غیر طبیعی در روش باز سازی FBP به ترتیب 2.8%؛ 25% و 39.6% بود در حالیکه در روش OSEM به ترتیب 18.8%، 43.8% و 68.8% اسکن ها غیر طبیعی بودند (P<0.001). توافق تفسیر(Kappa) در بین دو روش بازسازی معادل 0.48 بود (P<0.001). متوسط امتیاز جذبی تجمعی هر اسکن [summed score (SS)] که نشانه ای از شدت و وسعت نقص پرفیوژن می باشد در روش بازسازی FBP، 5.25 و در بازسازی OSEM معادل 8.08 بود (P<0.05). متوسطSS در روش OSEM و در جابجائی های برگشت پذیر به مدت های متفاوت (یک؛ دو و سه نما یا 30؛ 60 و 90 ثانیه ( به ترتیب 2.52 و 6 و 8.1 بود (p<0.05). همچنین در این روش بازسازی متوسطSS در جابجائی های به مقادیر یک؛ دو و سه پیکسل به ترتیب 3.85 و 8.77 و 11.58 بود (P<0.001). در جابجائی های غیر برگشت پذیر و در هر دو روش بازسازی هیچ موردی از تصویر طبیعی گزارش نشد. نتیجه گیری: مطالعه حاضر نشان داد که در روش باز سازی OSEM نسبت به روشFBP میزان آرتفکت های ناشی از حرکت بیمار بیشتر می باشد و نیز شدت و وسعت آرتفکت های حرکتی نیز در این روش بیشتر است. همچنین شدت آرتفکت ها با افزایش مدت جابجائی بیشتر می شود.

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نویسندگان: 

Faraji Hassan

اطلاعات دوره: 
  • سال: 

    1402
  • دوره: 

    13
  • شماره: 

    3
  • صفحات: 

    31-45
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    138
  • دانلود: 

    16
چکیده: 

A B S T R A C TFor choosing suitable place multiple Methods are introduced, which examine the qualities, Methods and patterns of location selection. The current Methods use Global approach and do not pay attention to spatial differences, environmental variation in variables, Local changes modeled by Local weighting indicators. It has been selected as a case study to evaluate the EMS center of Fars province and to evaluate the indicators of distance from the power plant, distance from logistics centers, industries, transportation terminals, hospitals, hotels and tourism, cities, rural areas and custom centers. has been used, using the AHP Method to weight the qualities, and then for Local weights, non-overlapping neighborhood filtering within a radius of 25 km are used and calculate the corresponding changes, quantity, ratio Presented in this article, the obtained weights, then the compute Local weighted layers, and then Local weight was multiplied in the normalized layers and the final layer were obtained. In the next step, it was combined and calculated to compare the data using the Global Method. The results of the two Methods were transferred to the points of the EMS and the results were analyzedExtended AbstractIntroductionIn geographical studies and spatial planning, there are different approaches to choosing the right place for all kinds of applications and uses, and a process is followed to choose the best places. This process includes stating the research problem (cognition), choosing the criteria and preferences of decision makers and how to determine the weight of indicators, combining criteria (design) and finally, choosing the best option. In the current Methods of spatial decision, the criteria are given a fixed weight, while in geographical locations, the distribution of geographical phenomena is not uniform. In this case, attention should be paid to the spatial distribution pattern of geographical phenomena based on the principle of sensitivity of the range of changes, the size of the range of changes affects the outputs, and the data with a smaller range of changes also have a lesser effect on the output. The data with a larger range of changes will have a more significant effect on the output. Therefore, in spatial analysis, indicators that have small changes are less important. Local models have been presented to model Local changes in spatial multi-criteria decision-making; in this research, the main issue is how to model the Local changes that affect the expected outputs. MethodologyThe research process is based on multi-criteria spatial decision-making Methods (national and Local). First, spatial patterns of indicators were analyzed through exploratory analyzes of ESDA spatial data. Then based on the review of the research criteria, the direct weighting Method was used to calculate the weight of the indicators, and the experts were asked to specify the weight of the criteria in the range of 1 to 10. The opinions were combined, and the final weight was obtained. First, the data were spatially modelled to model and calculate the Local weights. Then Block Statistics spatial filter without overlap was used to determine the neighborhood. The range of Local changes, maximum and minimum values, were calculated, and Local weights were obtained based on that. Finally, the information layers were descaled. After that, the unscaled criterion layers were multiplied by the national weights and the final national scores were obtained. In the next step, the data of the evaluated information layers (Local and national) were transferred to the points of emergency databases. Based on the analysis, the fit was done. Results and discussionGeneral or Global weights pay attention to the relative importance of indicators, which is the starting point for calculating Local weights. Based on the research results, the most critical indicators are industries, cities and hospitals, which are more important in the location of road emergency stations. However, in order to achieve better results, it is necessary to build a Local weight layer. The results of the research show that the indicators' weight and the difference in the criteria (general weight) are not equal in the entire geographical area, and the areas with a larger range of changes have a higher coefficient.Because, unlike general weights that are obtained based on different Methods, Local weights are estimated based on the principle of sensitivity of the range of changes and are changed spatially, and a fixed value is not considered for all areas. According to the research findings, the highest level in the general and Local evaluation Method corresponds to 0.5 to 0.7. Based on the Local (geographic) weight Method, it is less than the national or general Method in the range of 0.9 to 1. Furthermore, this is due to the more precise nature of this Method, which models the effects of Local changes. To evaluate the compliance of the emergency centers with the final maps of suitability assessment, the information on the suitability maps was transferred to the map of the emergency center points of Fars province. Based on the evaluation of 207 emergency stations, according to the general Method, 14 percent are in the high group (0.9-1), and according to the Local or geographical Method (16.9), percent are in this group. ConclusionAt the level of space and geographical regions, phenomena and geographical complications are not uniformly distributed, some phenomena have a homogeneous distribution, and some have a heterogeneous distribution. On the one hand, the phenomena and decision issues are affected by the context in which they are formed and evolve; on the other hand, these phenomena are placed in the network of mutual relations. Furthermore, the results of the set of phenomena may differ from the results of the phenomena individually and separately; in this article, an attempt has been made to address the issue that in spatial analysis and planning, it is necessary to pay attention to geographical differences in decision-making. Furthermore, it should not be evaluated in general terms of spatial decision problems; one of the Methods of modelling these differences and spatial changes is to consider the Local weight of the criteria. Based on the research findings, Local (geographical) and national analysis results are different and can better show these changes. On the other hand, the pattern of spatial differences also has its spatial pattern, and paying attention to these differences in spatial differences can be the subject of further studies. FundingThere is no funding support. Authors’ ContributionAuthors contributed equally to the conceptualization and writing of the article. All of the authors approved the content of the manuscript and agreed on all aspects of the work declaration of competing interest none. Conflict of InterestAuthors declared no conflict of interest. Acknowledgments We are grateful to all the scientific consultants of this paper.

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

Scientia Iranica

اطلاعات دوره: 
  • سال: 

    2019
  • دوره: 

    26
  • شماره: 

    3 (Transactions D: Computer Science and Engineering and Electrical Engineering)
  • صفحات: 

    1601-1607
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    290
  • دانلود: 

    0
چکیده: 

This paper studies the problem of Simultaneous Sparse Approximation (SSA). This problem arises in many applications that work with multiple signals maintaining some degree of dependency, e. g., radar and sensor networks. We introduce a new Method towards joint recovery of several independent sparse signals with the same support. We provide an analytical discussion of the convergence of our Method, called Simultaneous Iterative Method (SIM). In this study, we compared our Method with other group-sparse reconstruction techniques, namely Simultaneous Orthogonal Matching Pursuit (SOMP) and Block Iterative Method with Adaptive Thresholding (BIMAT), through numerical experiments. The simulation results demonstrated that SIM outperformed these algorithms in terms of the metrics Signal to Noise Ratio (SNR) and Success Rate (SR). Moreover, SIM is considerably less complicated than BIMAT, which makes it feasible for practical applications such as implementation in MIMO radar systems.

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نویسندگان: 

Moccari m. | LOTFI T.

اطلاعات دوره: 
  • سال: 

    2021
  • دوره: 

    15
  • شماره: 

    2
  • صفحات: 

    0-0
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    31
  • دانلود: 

    0
چکیده: 

This paper deals with the study of relaxed conditions for semi-Local convergence for a general Iterative Method, k-step Newton's Method, using majorizing sequences. Dynamical behavior of the mentioned Method is also analyzed via Julia set and basins of attraction. Numerical examples of nonlinear systems of equations will be examined to verify the given theory.

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اطلاعات دوره: 
  • سال: 

    1401
  • دوره: 

    52
  • شماره: 

    3
  • صفحات: 

    205-215
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    136
  • دانلود: 

    23
چکیده: 

Distance-based clustering Methods categorize samples by optimizing a Global criterion, finding ellipsoid clusters with roughly equal sizes. In contrast, density-based clustering techniques form clusters with arbitrary shapes and sizes by optimizing a Local criterion. Most of these Methods have several hyper-parameters, and their performance is highly dependent on the hyper-parameter setup. Recently, a Gaussian Density Distance (GDD) approach was proposed to optimize Local criteria in terms of distance and density properties of samples. GDD can find clusters with different shapes and sizes without any free parameters. However, it may fail to discover the appropriate clusters due to the interfering of clustered samples in estimating the density and distance properties of remaining unclustered samples. Here, we introduce Adaptive GDD (AGDD), which eliminates the inappropriate effect of clustered samples by adaptively updating the parameters during clustering. It is stable and can identify clusters with various shapes, sizes, and densities without adding extra parameters. The distance metrics calculating the dissimilarity between samples can affect the clustering performance. The effect of different distance measurements is also analyzed on the Method. The experimental results conducted on several well-known datasets show the effectiveness of the proposed AGDD Method compared to the other well-known clustering Methods.

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

HEIDARI ELHAM | TAVASSOLI SAJJAD

اطلاعات دوره: 
  • سال: 

    2017
  • دوره: 

    8
  • شماره: 

    4 (30)
  • صفحات: 

    59-72
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    265
  • دانلود: 

    0
چکیده: 

Content-based image retrieval (CBIR) has been an active research topic in the last decade. In this paper we proposed an image retrieval Method using Global and Local features. Firstly, for Local features extraction, SURF algorithm produces a set of interest points for each image and a set of 64-dimensional descriptors for each interest points and then to use Bag of Visual Words model, a clustering algorithm is used to obtain the visual vocabulary and each resulted centroid represent a visual word. Then, images are viewed as BoVW represented as histogram. In order to improve retrieval performance, Global feature is extracted by HSV color feature. Finally, this approach uses the combined Local and Global features as feature vectors to provide image retrieval. The COREL image database has been used for our experimental results. The experimental results show that the performance of the combination of both Local and Global features is much higher than each of them, which is applied separately.

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اطلاعات دوره: 
  • سال: 

    1395
  • دوره: 

    16
  • شماره: 

    8
  • صفحات: 

    207-217
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    536
  • دانلود: 

    202
چکیده: 

هدف اصلی این تحقیق، مدل سازی اثر گوشه آزاد در چندلایه های کامپوزیتی متعامد و زاویه دار گرافیت/اپوکسی، با استفاده از روش حل المان محدود و بر اساس مدل سراسری- موضعی می باشد. در این مدل، ناحیه سراسری با استفاده از تئوری مرتبه اول برشی و ناحیه موضعی، در مجاورت گوشه آزاد، با استفاده از تئوری لایروایز ردی، مدل می شوند. استفاده از این روش امکان تحلیل چندلایه های ضخیم زاویه دار و متعامد را به وجود می آورد. چندلایه های متعامد و زاویه دار به ترتیب تحت بار حرارتی و کشش یکنواخت قرار گرفته و اثرات تنش های بین لایه ای لبه آزاد و گوشه آزاد مورد بررسی قرار می گیرد. اعتبارسنجی نتایج حاضر توسط نتایج در دسترس در تحقیقات پیشین صورت می گیرد که نشان دهنده تطابق خوبی است. نتایج تحقیق حاضر نشان می دهند هنگامی که چندلایه متعامد تحت بار حرارتی قرار می گیرد توزیع تنش های بین لایه ای در هر دو جهت طول و عرض چندلایه یکنواخت است. در صورتیکه برای بار کششی تک جهته تنش های بین لایه ای در دو راستای چندلایه دارای توزیع متفاوت می باشد. همچنین نتایج نشان می دهند که در چندلایه های زاویه دار تحت کشش یکنواخت با افزایش زاویه الیاف، اثر گوشه آزاد افزایش می یابد و بیشترین تنش های بین لایه ای در لایه های 30 درجه در مجاورت لبه های آزاد رخ می دهند. بعلاوه نتایج ثابت می کنند در لایه های با زاویه ی الیاف کمتر از 30 درجه، اثرات لبه آزاد و گوشه آزاد، تقریبا مشابه است. مطالعه پارامتری بر روی ضخامت و چیدمان لایه های چندلایه نشان می دهد که هر دو پارامتر بر روی تنش های بین لایه ای در گوشه ی آزاد تاثیر بسزایی دارند.

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نویسندگان: 

نشریه: 

MEDICAL EDUCATION

اطلاعات دوره: 
  • سال: 

    2019
  • دوره: 

    53
  • شماره: 

    1
  • صفحات: 

    25-31
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    56
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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نویسندگان: 

Bagheri Vakilabad Ali

اطلاعات دوره: 
  • سال: 

    2020
  • دوره: 

    17
  • شماره: 

    1
  • صفحات: 

    91-98
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    37
  • دانلود: 

    0
چکیده: 

Let $ H$ be a Hilbert space and $C$ be a closed, convex and nonempty subset of $H$. Let $T:C \rightarrow H$ be a non-self and non-expansive mapping. V. Colao and G. Marino with particular choice of the sequence  $\{\alpha_{n}\}$ in Krasonselskii-Mann algorithm, ${x}_{n+1}={\alpha}_{n}{x}_{n}+(1-{\alpha}_{n})T({x}_{n}),$ proved both weak and strong converging results. In this paper, we generalize their algorithm and result, imposing some conditions upon the set $C$ and finite many mappings from $C$ in to $H$, to obtain a converging sequence to a common fixed point for these non-self and non-expansive mappings.

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