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نتیجه جستجو - ریاضی

تعداد مقالات یافته شده: 96
ردیف عنوان نوع
1 Locating switches
تعویض مکان-2019
In this paper, a novel problem in transshipment networks has been proposed. The main aims of this pa- per are to introduce the problem and to give useful tools for solving it both in exact and approximate ways. In a transshipment network it is important to decide which are the best paths between each pair of nodes. Representing the network by a graph, the union of thesepaths is a delivery subgraph of the original graph which has all the nodes and some edges. Nodes in this subgraph which are adjacent to more than two nodes are called switches because when sending the flow between any pair of nodes, switches on the path must adequately direct it. Switches are facilities which direct flows among users. The installation of a switch involves the installation of adequate equipment and thus an allocation cost. Furthermore, traversing a switch also implies a service cost or allocation cost. The Switch Location Prob- lem is defined as the problem of determining which is the delivery subgraph with the total lowest cost. Two of the three solutions approaches that we propose are decomposition algorithms based on articula- tion vertices, the exact and the math-heuristic ones. These two approaches could be embedded in expert systems for locating switches in transshipment networks. The results should help a decision maker to select the adequate approach depending on the shape and size of the network and also on the exter- nal time-limit. Our results show that the exact approach is a valuable tool if the network has less than 10 0 0 nodes. Two upsides of our heuristics are that they do not require special networks and give good solutions, gap-wise. The impact of this paper is twofold: it highlights the difficulty of adequately locating switches and it emphasizes the benefit of decomposing algorithms.
Keywords: Discrete location | Math-heuristic | Articulation vertex | Block-Cutpoint graph
مقاله انگلیسی
2 استفاده از رسانه های اجتماعی برای شناسایی جذابیت گردشگری در شش شهر ایتالیا
سال انتشار: 2019 - تعداد صفحات فایل pdf انگلیسی: 7 - تعداد صفحات فایل doc فارسی: 18
تکامل فناوری و گسترش شبکه های اجتماعی به افراد اجازه داده است که مقادیر زیادی داده را در هر روز تولید کنند. شبکه های اجتماعی کاربرانی را فارهم می کند که به اطلاعات دسترسی دارند. هدف این مقاله تعیین جذابیت های شهرهای مختلف گردشگری ازطریق بررسی رفتار کاربران در شبکه های اجتماعی می باشد. پایگاه داده ای شامل عکس های جغرافیایی واقع شده در شش شهر می باشد که به عنوان یک مرکز فرهنگی و هنری در ایتالیا عمل می کنند. عکس ها از فلیکر که یک بستر به اشتراک گذاری داده می باشد دانلود شدند. تحلیل داده ها با استفاده از دیدگاه مدلهای یادگیری ریاضی و ماشینی انجام شد. نتایج مطالعه ما نشانگر نقشه های شناسایی رفتار کاربران، گرایش سالانه به فعالیت تصویری در شهرها و تاکید بر سودمند بودن روش پیشنهادی می باشد که قادر به تامین اطلاعات مکانی و کاربری است. این مطالعه تاکید می کند که چگونه تحلیل داده های اجتماعی می تواند یک مدل پیشگویانه برای فرموله کردن طرح های گردشگری خلق کند. در انتها، راهبردهای عمومی بازاریابی گردشگری مورد بحث قرار می گیرند.
مقاله ترجمه شده
3 Optimization under uncertainty in the era of big data and deep learning: When machine learning meets mathematical programming
بهینه سازی تحت عدم اطمینان در عصر داده های بزرگ و یادگیری عمیق: وقتی یادگیری ماشین با برنامه نویسی ریاضی ملاقات می کند-2019
This paper reviews recent advances in the field of optimization under uncertainty via a modern data lens, highlights key research challenges and promise of data-driven optimization that organically integrates machine learning and mathematical programming for decision-making under uncertainty, and identifies potential research opportunities. A brief review of classical mathematical programming techniques for hedging against uncertainty is first presented, along with their wide spectrum of applications in Process Systems Engineering. A comprehensive review and classification of the relevant publications on data- driven distributionally robust optimization, data-driven chance constrained program, data-driven robust optimization, and data-driven scenario-based optimization is then presented. This paper also identifies fertile avenues for future research that focuses on a closed-loop data-driven optimization framework, which allows the feedback from mathematical programming to machine learning, as well as scenario- based optimization leveraging the power of deep learning techniques. Perspectives on online learning- based data-driven multistage optimization with a learning-while-optimizing scheme are presented.
Keywords: Data-driven optimization | Decision making under uncertainty | Big data | Machine learning | Deep learning
مقاله انگلیسی
4 Analysis of automotive gearbox faults using vibration signal
تحلیل خطای گیربکس اتومبیل با استفاده از سیگنال لرزش-2019
The objective of this work is to identify the presence of damages and to diagnose the damaged component in automotive gearboxes by comparing the vibration signals of the damaged and undamaged systems. The vibration signals were obtained in the gearboxes test bench taking into account ten samples approved by subjective method (based on human hearing) and three gearboxes damaged (two with bearing damaged and one with gear tooth damaged). The signals were obtained through five accelerometers positioned in the samples and each test comprises ten different steps with different coupling configurations of the gears. Different signal analysis techniques based on wavelet transform, mathematic morphology and energy (entropy) were used to verify the presence of damage in the systems. The presence of damage to the systems is verified directly by comparing the energy levels and entropy of the signals of the damaged and undamaged systems for the ten steps tests. A signal processing technique combining pattern spectrum and selective filtering in certain frequencies ranges was used for identification of component failures. This technique will, further on, be part of a diagnostic and quality control system that will be able to evaluate and identify the damaged component at the automotive gearbox.
Keywords: Automotive gearbox | Damage | Mathematical morphology | Wavelet | Entropy
مقاله انگلیسی
5 Application of machine learning to laboratory safety management assessment
کاربرد یادگیری ماشین در ارزیابی مدیریت ایمنی آزمایشگاهی-2019
This paper proposes a new method to evaluate laboratory safety management based on machine learning that aims to address the shortcomings of traditional laboratory safety evaluation methods, including poor accuracy, large influence of human factors, and lack of a unified evaluation system. In this paper, the safety data of laboratories in Southwest University were collected using a safety checklist, and the weight of each factor affecting laboratory safety was analyzed using a Fuzzy Analytic Hierarchy Process (FAHP). The simulation results showed that the model gave a more accurate and reasonable safety risk level of the laboratory, verified the rationality and feasibility of the established method, and realized potential loopholes in the process of laboratory management and college students operations. According to the evaluation results, the machine learning principle and the existing maintenance knowledge of the evaluation knowledge base are applied to provide effective measures and suggestions for users to complete the process of risk assessment. Through risk assessment, the professional skill and the incident control could be improved. The model was easy to operate and has a good application value for ensuring the personal and property safety of laboratory users.
Keywords: Machine learning | Fuzzy mathematics | Laboratory safety management evaluation | Risk reduction
مقاله انگلیسی
6 Transportation problems for intermodal networks: Mathematical models, exact and heuristic algorithms, and machine learning
مشکلات حمل و نقل برای شبکه های intermodal: مدل های ریاضی ، الگوریتم های دقیق و اکتشافی ، و یادگیری ماشین-2019
This paper presents a combinatorial problem called a pick-up routing problem with a three-dimensional (3D-PRP) loading constraint, clustered backhauls at the operational level, and train loading at the tactical level for an intermodal transportation network. A two-phase approach, called clustering first, packing- routing second, is proposed for use during the first stage. The clustering of backhauls is carried out using the k-means algorithm. A hybrid approach is provided, which combines the packing of orders by first solving a 3D loading problem for each cluster using machine learning with a best-fit-first strategy, with routing using a genetic algorithm. During the second stage, the train-loading problem is solved using a mixed integer programming approach to minimise the total costs by incorporating various cost types, in which detention and demurrage costs are taken into account. All solution approaches are computationally evaluated on real-world data provided by an international logistics firm and new randomly generated instances. Comparisons are carried out using both exact solution methods and heuristic approaches, and the proposed approach was shown to be more effective for real-world problems.
Keywords: Intermodal transportation | Pick-up routing with three-dimensional | loading | Train loading | Heuristic approach | Mathematical model, Machine learning
مقاله انگلیسی
7 A linearized model for academic staff assignment in a Brazilian university focusing on performance gain in quality indicators
یک مدل خطی سازی شده برای تخصیص ستاد علمی در یک دانشگاه برزیلی تمرکز کننده روی بهره عملکردی در شاخص های کیفیت-2018
Private Higher Education Institutions (HEI) often have shares in stock markets to attract investment. A key element for a good appreciation on the market is a good evaluation in performance indicators of academic quality. In Brazil a main component of such academic quality indicators is directly computed after the assignment of faculty members to courses. We develop mathematical models to support decision making in the assignment of faculty members to courses in a private HEI in Brazil. It turns out that the original problem is a nonlinear integer programming problem, and to deal with large instances found in practice we propose to use a linearized model instead. We conduct computational experiments with two main purposes: to evaluate the quality of the solutions obtained with the linear integer model when compared to the ones obtained with the original nonlinear integer model, and to evaluate the potential of gains with the linear integer model when compared to actual assignments. In the latter case numerical results on real instances from the HEI under study show the proposed approach effective to improve the indicators of the HEI due to a better assignment of faculty members to courses than observed in practice.
keywords: Academic staff assignment problem |Operations research in education |Mathematical modeling
مقاله انگلیسی
8 The mechanics of commercial banking liberalization and growth
ریاضیات آزادسازی و رشد بانکداری تجاری-2018
This paper formalizes the effects of liberalization across the border of deposit-taking and lending activities on the regime of competition in the banking market and on the rate of growth of the economy. We extend two economy based Deidda (2006)’s banking model in which originally each economy hosts at least one operating bank. We introduce two GATS-defined modes of commercial banking liberalization – namely the Commercial Presence mode and the Cross-Border mode. Additionally, we introduce the possibility of strategic behavior by competing banks in equilibrium. The extended model provides a causal link between the cost structure of the banking industry, the regime of competition in the liberalized banking sector and the rate of growth of the economy under alternative modes of liberalization. In particular, we show a threshold effect in terms of economic development: above certain economic development the banking sector operates competitively and supports an accelerating rate of growth, generating a bidirectional, self-reinforcing link between commercial banking liberalization and growth. The pace of growth is further increased, with respect to a scenario where such behavior is not present, by the presence of strategic behavior by competing banks in equilibrium.
keywords: Commercial banking| Financial service liberalization| Economic growth
مقاله انگلیسی
9 الگوریتم چند جمله ای مدل انبارداری با تاخیر کامل در سفارش و تقاضای همبسته ایجاد شده توسط فروش تقاطعی
سال انتشار: 2018 - تعداد صفحات فایل pdf انگلیسی: 6 - تعداد صفحات فایل doc فارسی: 23
در یک مقاله چاپ شده در مجله بین المللی اقتصادهای تولید (مدل و الگوریتم اکتشاف مسئله تجدید تدارکات مشترک با ترتیب بندی کامل و تقاضای همبسته، ژنگ و همکاران، صحفات33 تا 41)، نویسنده ها یک مدل مسئله تجدید تدارکات مشترک با ترتیب بندی کامل و تقاضای همبسته ایجاد شده توسط فروش تقاطعی را پیشنهاد کرده اند. این مدل به کمینه کردن یک تابع باتوجه به چندگانگی های یک چرخه سفارش یک کالای مهم تبدیل شد و یک الگوریتم اکتشاف برای راه حل های تقریبا" بهینه تولید شد. در این مقاله، ما مسئله را بررسی مجدد می کنیم و ویژگی ریاضی این مدل را جهت تولید یک الگوریتم واقعی تحلیل می کنیم. این الگوریتم می تواند به بهینگی عمومی دست یابد و پیچیدگی چند جمله ای را نشان می دهد.
کلیدواژه ها: انبارداری | مسئله تجدید تداکرات مشترک | الگوریتم چند جمله ای | تاخیر کامل در سفارش | فروش تقاطعی
مقاله ترجمه شده
10 انطباق وزنی بهینه مبتنی بر فرد برای شبکه های توزیع ناهمگن جهانی
سال انتشار: 2018 - تعداد صفحات فایل pdf انگلیسی: 17 - تعداد صفحات فایل doc فارسی: 39
مطالعه ما درباره¬ی توزیع اپیدمیک در شبکه های وزنی، جهت دار و ناهمگن است. یک مکانیسم انطباق وزنی مبتنی بر فرد پیشنهاد شد که در آن قدرت تماس افراد با توجه به سطح توزیع شبکه قابل انطباق است. فرمول کنترل بهینه به منظور اشاره به ارتباط بین سطح سرایت جهانی و هزینه انطباق وزنی محلی مطابق با توپولوژي شبکه اتصال زیرزمینی ارائه شده است. وجود راه حل برای مسئله کنترل بهینه، به اثبات رسید و با استفاده از آنالیز ریاضی دقیق به بیان صریح دست یافتیم. علاوه بر این، به طوری تقریبی به راه حل بهینه رسیدیم و بصورت انحصاری آن را با یک تابع هزینه خاص بررسی کردیم. در یک سری از آزمایش های عددی، روش پیاده سازی forward-backward برای واسنجی نتایج تئوری به دست آمده، اتخاذ شد. یافته های ما بینش های جدید راجع به رابطه بین توزیع اپیدمیک در شبکه های پیچیده ناهمگن با دینامیک پاسخ های رفتاری و هزینه های استراتژی کنترل را به همراه پیامدهای مهم توسعه آتی سیاست های بهداشت عمومی تطبیقی مربوطه؛ پوشش نمیدهد.
کلید واژه ها: توزیع جهانی| انطباق وزنی بهینه | شبکه های ناهمگن وزنی | رفتار تطبیقی | مدل ریاضی | اپیدمیولوژی
مقاله ترجمه شده
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