Mathematical Research Articles

Distance Mathematics Education as a Means for Tackling Impulse Control Disorder: The Case of a Young Convict.

While distance education (DE) is often considered as a means to provide mathematical education to students in remote locations or to promote the professional development of mathematics teachers, th ...

ESTUDOS DE QSAR PARA SARS-CoV-2

The generation of mathematical models through the quantitative relationship between the chemical structure and the biological activity (QSARs) of compounds was used in this investigation Mathematical models were generated from compounds available in literature that predicting the biological activity against SARS-CoV-2 The data indicate that the parameters that most interfere and allow to validate the equations are: number of hydrogen bonding donors, maximum projection radius and length perpendicular to the minimum area This allows us to infer that there is synergism between the basic capacity of the cysteine protein action site present in the virus and the geometric conditions for the three-dimensional alignment to potential compounds with anti-SARS-CoV-2 action The authors highlight that mathematical models assist in chemical research, but do not replace evaluation of the efficacy in vitro, in vivo, pre-clinical and clinical studies, which are essential for dosage, release or authorization to use any medication or supplement © 2020 Sociedade Brasileira de Quimica All rights reserved

Modeling the wetting deformation behavior of rockfill dams

A mathematical wetting model is usually used to predict the deformation of core wall rockfill dams induced by the wetting effect. In this paper, a series of wetting triaxial tests on a rockfill was conducted using a large-sized triaxial apparatus, and the wetting deformation behavior of the rockfill was studied. The wetting strains were found to be related to the confining pressure and shear stress levels, and two empirical equations, which are regarded as the proposed mathematical wetting model, were proposed to express these properties. The stress and deformation of a core wall rockfill dam was studied by using finite element analysis and the proposed wetting model. On the one hand, the simulations of the wetting model can estimate well the observed wetting strains of the upstream rockfill of the dam, which demonstrated that the proposed wetting model is applicable to express the wetting deformation behavior of the rockfill specimen. On the other hand, the simulated additional deformation of the dam induced by the wetting effect is thought to be reasonable according to practical engineering experience, which indicates the potential of the model in dam engineering.

Design optimization in hard turning of E19 alloy steel by analysing surface roughness, tool vibration and productivity

In the present work, the optimization of machining parameters to achieve the desired technological parameters such as surface roughness, tool radial vibration and material removal rate have been carried out using response surface methodology (RSM). The hard turning of EN19 alloy steel with coated carbide (GC3015) cutting tools was studied. The main problem faced in manufacturer of hard and high precision components is the selection of optimum combination of cutting parameters for achieving required quality of surface finish with maximum production rate. This problem can be solved by development of mathematical model and execution of experiments by RSM. A face centred central composite design (FCCD), which comes under the RSM approach, with cutting parameters (cutting speed, feed rate and depth of cut) was used for statistical analysis. A second-order regression model were developed to correlate the cutting parameters with surface roughness, tool vibration and material removal rate. Consequently, numerical and graphical optimization were performed to obtain the most appropriate cutting parameters to produce the lowest surface roughness with minimal tool vibration and maximum material removal rate using desirability function approach. Finally, confirmation experiments were performed to verify the pertinence of the developed mathematical models.

Numerical analysis of thermal post-buckling strength of laminated skew sandwich composite shell panel structure including stretching effect

The computational post-buckling strength of the tilted sandwich composite shell structure is evaluated in this article. The computational responses are obtained using a mathematical model derived using the higher-order type of polynomial kinematic in association with the through-thickness stretching effect. Also, the sandwich deformation behaviour of the flexible soft-core sandwich structural model is expressed mathematically with the help of a generic nonlinear strain theory i.e. Green-Lagrange type strain-displacement relations. Subsequently, the model includes all of the nonlinear strain terms to account the actual deformation and discretized via displacement type of finite element. Further, the computer code is prepared (MATLAB environment) using the derived higher-order formulation in association with the direct iterative technique for the computation of temperature carrying capacity of the soft-core sandwich within the post-buckled regime. Further, the nonlinear finite element model has been tested to show its accuracy by solving a few numerical experimentations as same as the published example including the consistency behaviour. Lastly, the derived model is utilized to find the temperature load-carrying capacity under the influences of variable factors affecting the soft-core type sandwich structural design in the small (finite) strain and large deformation regime including the effect of tilt angle.

Розроблення фізико-математичної моделі скочування бутів гірської породи з породних відкосів

Розроблення фізико-математичної моделі скочування бутів гірської породи з породних відкосів

Disorder for deficit attention by hyperactivity and inclusion in education

If a teacher does not know what Attention Deficit hyperactivity Disorder (ADHD) is, he will not be able to detect if it exists in the classroom, this is the most common neuropsychiatric condition in young children, symptomatically evolutionary disorder, manifesting itself differently according to age. It is common in boys who, in girls, among the most visible expressions are: behavioral problems (does not obey, does not work, nor let work), difficult concentration, learning difficulties in areas such as mathematics and especially in the language (writing and reading) which causes poor school performance. This research is intended to make an introduction to what ADHD is and its focus on the educational area, contributing meaningful information that helps teachers to establish strategies that allow the inclusion of those who are affected.

Post-buckling analysis of Mindlin Cut out-plate reinforced by FG-CNTs

In the present research post-buckling of a cut out plate reinforced through carbon nanotubes (CNTs) resting on an elastic foundation is studied. Material characteristics of CNTs are hypothesized to be altered within thickness orientation which are calculated according to Mori-Tanaka model. For modeling the system mathematically, first order shear deformation theory (FSDT) is applied and using energy procedure, the governing equations can be derived. With respect to Rayleigh-Ritz procedure as well as Newton-Raphson iterative scheme, the motion equations are solved and therefore, post-buckling behavior of structure will be tracked. Diverse parameters as well as their reactions on post-buckling paths focusing cut out measurement, CNT\'s volume fraction and agglomeration, dimension of plate and an elastic foundation are investigated. It is revealed that presence of a square cut out can affect negatively post-buckling behavior of structure. Moreover, adding nanocompsits in the matrix leads to enhancement of post-buckling response of system.

对高等数学课程教学改革的几点思考

对高等数学课程教学改革的几点思考

Dynamic analysis of functionally graded nonlocal nanobeam with different porosity models

This article presented a nanoscale modified continuum model to investigate the free vibration of functionally graded (FG) porous nanobeam by using finite element method. The main novelty of this manuscript is presenting effects of four different porosity models on vibration behaviors of nonlocal nanobeam structure including size effect, that not be discussed before The proposed porosity models are, uniform porosity distribution, symmetric with mid-plane, bottom surface distribution and top surface distribution. The nano-scale effect is included in modified model by using the differential nonlocal continuum theory of Eringen that adding the length scale into the constitutive equations as a material parameter constant. The graded material is distributed through the beam thickness by a generalized power law function. The beam is simply supported, and it is assumed to be thin. Therefore, the kinematic assumptions of Euler-Bernoulli beam theory are held. The mathematical model is solved numerically using the finite element method. Results demonstrate effects of porosity type, material gradation, and nanoscale parameters on the free vibration of nanobeam. The proposed model is effective in vibration analysis of NEMS structure manufactured by porous functionally graded materials.

An Investigation of Pedagogical Content Knowledge of Secondary School Mathematics Teachers in Relation with Triangle and Quadrilateral Concepts

Bu calismanin amaci ortaokul matematik ogretmenlerinin ucgenler ve dortgenler konusuna iliskin pedagojik alan bilgilerini; konu alani ve ogrenci bilgisi baglaminda incelemektir. Arastirma nitel arastirma yontemlerinden ozel durum yontemiyle yurutulmustur. Orneklem, 0-5 yil, 6-10 yil ve 11yil ve uzeri mesleki deneyim gruplarindan esit sayida secilen toplam 12 ortaokul matematik ogretmeninden olusmaktadir. Veriler, ucgenler ve dortgenler konusundaki cesitli senaryo durumlarini iceren 9 acik uclu soru ve yari yapilandirmis mulakatlar ile elde edilmistir. Elde edilen veriler, icerik analizi yontemiyle analiz edilmistir. Bulgular, ortaokul matematik ogretmenlerinin ucgenler ve dortgenlere yonelik pedagojik alan bilgisinin konu alani bileseninde istenilen duzeyde olmadigini; ancak ogrenci bilgisi bileseninde, konu alani bilgisi bilesenine nispeten daha iyi duzeyde oldugunu gostermektedir. Ayrica ogretmenlerin cogunun ucgenler ve dortgenler konularina yonelik konu alani bilgilerinde ortaokul ogrencileri ile benzeyen kavram yanilgilarina sahip olduklari belirlenmistir.

Mathematical model of passenger catamarans optimization for a given sea route

Представлены результаты исследования потенциально эффективных маршрутов скоростных пассажирских катамаранов в Социалистической Республике Вьетнам. Разработана математическая модель определения количества катамаранов и оценки целесообразности их закрепления за конкретной линией перевозок. Проанализированы оптимальные варианты расстановки судов по выбранным маршрутам с учетом сезонности и региональных особенностей перевозок, рассмотрена возможность развития морских перевозок за счет новых направлений, позволяющих повысить интенсивность и объемы туристических пассажиропотоков. Усовершенствована методика оценки экономической эффективности скоростных пассажирских катамаранов в части учета динамики распределения пассажиропотока в течение года, определения коэффициентов загрузки судов пассажирами в зависимости от количества посадочных мест и судов на линии, актуализированы расчеты построечной стоимости катамарана и эксплуатационных расходов. Установлено, что в зависимости от выбора экономических критериев результаты оптимизации проектных характеристик скоростных пассажирских катамаранов отличаются. Ключевые слова: Социалистическая Республика Вьетнам, скоростные пассажирские катамараны, оптимизация проектных характеристик, количество судов, перспективные маршруты

Research on the Strategy of Applying Mathematics to Promote Information Application

Research on the Strategy of Applying Mathematics to Promote Information Application

Structural lightweight concrete containing expanded poly-styrene beads; Engineering properties

Light-Weight Concrete containing Expanded Poly-Styrene Beads (EPS-LWC) is an approved structural and non-structural material characterized by a considerably lower density and higher structural efficiency, compared to concrete containing ordinary aggregates. The experimental campaign carried out in this project provides new information on the mechanical properties of structural EPS-LWC, with reference to the strength and tension (by splitting and in bending), the modulus of elasticity, the stress-strain curve in unconfined compression, the absorbed energy under compression and reinforcement-concrete bond. The properties measured at seven ages since casting, from 3 days to 91 days, in order to investigate their in-time evolution. Mathematical relationships are formulated as well, between the previous properties and time, since casting. The dependence of the compressive strength on the other mechanical properties of EPS-LWC is also described through an empirical relationship, which is shown to fit satisfactorily the experimental results.

Research Slightly double fuzzy continuous functions via $e$-open sets P. Periyasamy 1 , A. Vadivel 2 *, G. Saravanakumar 3 and V. Chandrasekar 4 Malaya Journal of Matematik : Special Issue, Issue 1, 2020, Pages:570-575 DOI: 10.26637/MJM0S20/0109 | Full Article PDF | PDF size (1,412.53 KB) Research An $O(n)$-time algorithm to compute minimum $k$-hop connected dominating set of interval graphs

Research Slightly double fuzzy continuous functions via $e$-open sets P. Periyasamy 1 , A. Vadivel 2 *, G. Saravanakumar 3 and V. Chandrasekar 4 Malaya Journal of Matematik : Special Issue, Issue 1, 2020, Pages:570-575 DOI: 10.26637/MJM0S20/0109 | Full Article PDF | PDF size (1,412.53 KB) Research An $O(n)$-time algorithm to compute minimum $k$-hop connected dominating set of interval graphs

Buckling of carbon nanotube reinforced composite plates supported by Kerr foundation using Hamilton’s energy principle

This paper investigates the buckling behavior of carbon nanotube-reinforced composite plates supported by Kerr foundation model. In this foundation elastic of Kerr consisting of two spring layers interconnected by a shearing layer. The plates are reinforced by single-walled carbon nanotubes with four types of distributions of uniaxially aligned reinforcement material. The analytical equations are derived and the exact solutions for buckling analyses of such type\'s plates are obtained. The mathematical models provided, and the present solutions are numerically validated by comparison with some available results in the literature. Effect of various reinforced plates parameters such as aspect ratios, volume fraction, types of reinforcement, parameters constant factors of Kerr foundation and plate thickness on the buckling analyses of carbon nanotube-reinforced composite plates are studied and discussed.

Математическое моделирование динамических процессов в системе питания маршевого двигателя космических ступеней ракет-носителей на активных и пассивных участках траектории полета

Математическое моделирование динамических процессов в системе питания маршевого двигателя космических ступеней ракет-носителей на активных и пассивных участках траектории полета

Evaluation in a Differential Equations Course Supported by Online Mathematics Material in Context

La finalidad de esta investigación es evaluar, por un lado, el aprovechamiento escolar en un curso de ecuaciones diferenciales cuando se implementa material didáctico contextualizado en circuitos eléctricos con el uso de la plataforma Moodle como herramienta de apoyo y por el otro evaluarla percepción de los alumnos respecto a la utilidad de dicha plataforma. La investigación es de tipo mixta (cuantitativa y cualitativa), se fundamenta teórica y metodológicamente en la Matemática en el Contexto de las Ciencias. La evaluación cuantitativa se establece mediante un comparativo entre estudiantes de ingeniería electrónica: grupo control y grupo experimental. Los resultados indican que existe relación entre la aplicación del material didáctico con el uso de la plataforma Moodle y la obtención de mejoras en el aprendizaje de las ecuaciones diferenciales en el contexto de los circuitos eléctricos. La evaluación cualitativa se establece mediante la técnica de grupos focales donde los alumnos opinaron que la plataforma Moodle les ayuda a tener un mejor entendimiento de la materia y a desarrollar un aprendizaje autónomo.

Optimization of steel-concrete composite beams considering cost and environmental impact

In the optimized structure sizing, the optimization methods are inserted in this context in order to obtain satisfactory solutions, which can provide more economical structures, besides allowing the consideration of the factors related to the environmental impacts in the structural design. This work proposes a mathematical model for the optimization of steel-concrete composite beams aiming to minimize the monetary cost and the environmental impact, using the Harmonic Search optimization method. Discrete variables were the dimensions of the steel profiles and the thickness of the collaborating slab of the composite steel-concrete beam. The proposed model was implemented in Fortran programming language and based on improvements in the structure of the optimization method proposed by Medeiros and Kripka (2017). To prove the effectiveness and applicability of the model, as well as the Harmonic Search method, analyzes were performed with different configurations of steel-concrete composite beams, in order to provide guidelines that make the use of these systems more streamlined. In general, the Harmonic Search optimization method has proved to be efficient in the search for the optimized solutions, as well as important considerations on the optimization of the monetary and environmental costs of steel-concrete composite beams were obtained from the developed examples.

Концепция структурного закона и методология структурализма в неклассической науке

В эпистемологии закон преимущественно рассматривается в общем виде. В статье предпринята попытка обосновать, что на стадии неклассической науки сформировалась установка на открытие структурных законов во всех ее областях. Эмпирической базой статьи является анализ структурного зако-на, данный самими учеными – А. Эйнштейном, Н. Бурбаки, Ф. де Соссюром, В. Шкловским, В. Проппом, К. Леви-Строссом и др., а также оценки методологов структурализма (Р. Барта, Ж. Делёза и др.). В первые десятилетия ХХ в. исследователи (в физике, математике, лингвистике, литературо-ведении) приходят к выводу, что именно законы статики/синхронии/ст а-бильности позволяют раскрыть внутренний мир исследуемых объектов, их относительную автономию. Поиск структурных законов связан с процедура-ми деконструкции исходных объектов и их моделирования в виде языковых систем. Формальный и знаковый характер элементов, структурность как порядок их отношений позволяют выйти на теоретический уровень исследова-ния, связанный с открытием структурных законов.