Cure Kinetics and Inverse Analysis of Epoxy-Amine Based Adhesive Used for Fastening Systems

Thermosetting polymers are used in building materials, for example adhesives in fastening systems. They harden in environmental conditions with a daily temperature depending on the season and location. This curing process takes hours or even days effected by the relatively low ambient temperature necessary for a fast and complete curing. As material properties depend on the degree of cure, its accurate estimation is of paramount interest and the main objective in this work. Thus, we develop an approach for modeling the curing process for epoxy based thermosetting polymers. Specifically, we perform experiments and demonstrate an inverse analysis for determining parameters in the curing model. By using calorimetry measurements and implementing an inverse analysis algorithm by using open-source packages, we obtain 10 material parameters describing the curing process. We present the methodology for two commercial, epoxy based products, where a statistical analysis provides independence of material parameters leading to the conclusion that the material equation is adequately describing the material response.

Ferromagnetic Hysteresis by Heisenberg Partition Function and Its Processing Methods in Nanoparticle Magnetization Modeling

The Heisenberg {\it ab initio} theory of magnetization is developed to apply for multilayer nanoparticles. The theory is based on distribution and partition functions modification with account the difference between exchange integral and closest neighbour numbers, that change the system of resulting transcendental equation for magnetization and its reversal to form either a paramagnetic type curve or hysteresis loops patterns. The equations are obtained within the Heisenberg partition function construction by Heitler diagonalization of energy matrix via irreducible representations of permutation symmetry group. A combination with the Gauss distribution gives the explicit expression for the partition function in the asymptotic limit] at large spin range in terms of transcendent function. The exchange integral, as a parameter of the equation of state (material equation) is evaluated from Curie temperature value by means of a formula derived within the presented theory. Methods of data processing from the simultaneous solution of the material equation system are proposed. The multi-valued function of hysteresis loop is found by combination of graphical approach and special procedure for elimination of mistaken peaks and prolapses of the patterns. The theory and computation methods are applied to spherical particles with separate surface layers consideration. The contribution of the surface layers, that are specified by number of closest neighbors and exchange integrals into overall magnetization, is studied for two-layer and three-layer models, that are discussed and compared graphically.

#MeToo, the ICTY, and Intersectionality in Postsocialist Global Capitalism

In this essay, we theorize and analyze (some of) the intercultural and intersecting structures that undergird rape and its representation in #MeToo via testimonial examples from rape survivors at the International Criminal Tribunal for the former Yugoslavia (ICTY). While we recognize the importance of the ICTY’s ruling and of #MeToo, we remain critical of the conditions that necessitated them and that continue to mark women’s bodies as vulnerable. Utilizing both postsocialist and postcolonial feminist theory as a lens, we specifically look to how bodies are articulated both as capital/property and, in the same international judicial frame, vessels for punishment and justice. We focus on how the ICTY defined justice for rape on a mediated international stage, how identities and cultures were situated discursively in the trial, and the implications for thinking through justice for intersectionality in #MeToo. Our claim is that the symbolic and material equation of women/women’s bodies as property is foundational to the operations of capital. With this framework in mind, it may be useful to consider how undoing capital may in turn challenge the normalization of women’s precarity, victimization, and therefore, experiences of sexual violence.

Dynamic Analysis of a Viscoelastic Nanobeam

Vibration of an axially loaded viscoelastic nanobeam is analyzed in this study. Viscoelasticity of the nanobeam is modeled as a Kelvin-Voigt material. Equation of motion and boundary conditions for viscoelastic nanobeam are provided with help of Eringen’s Nonlocal Elasticity Theory. Initial conditions are used in solution of governing equation of motion. Damping effect of the viscoelastic nanobeam structure is investigated. Nonlocal effect on natural frequency and damping of nanobeam and critical buckling load is obtained.

PENERAPAN MODEL PEMBELAJARAN KOOPERATIF TIPE NUMBERED HEADS TOGETHER (NHT) UNTUK MENINGKATKAN HASIL BELAJAR SISWA PADA MATERI PERSAMAAN KUADRAT KELAS X IPA A SMA NEGERI 1 AMPIBABO

Abstrak: Tujuan penelitian ini adalah untuk memperoleh deskripsi tentang penerapan model pembelajaran kooperatif tipe Numbered Heads Together (NHT) yang dapat meningkatkan hasil belajar siswa pada Materi Persamaan Kuadrat Kelas SMA Negeri 1 Ampibabo. Jenis penelitian yang digunakan adalah penelitian tindakan kelas (PTK) yang mengacu pada desain penelitian Kemmis dan Mc. Taggart. Hasil penelitian menunjukan bahwa penerapan model pembelajaran kooperatif tipe NHT yang dapat meningkatkan hasil belajar siswa pada materi persamaan kuadrat di kelas X IPA A SMA Negeri 1 Ampibabo, dengan mengikuti fase-fase sebagai berikut: (1) penomoran, (2) mengajukan pertanyaan atau permasalahan, (3) berpikir bersama, dan (4) menjawab. Kata kunci: Numbered Heads Together, hasil belajar, persamaan kuadrat. Abstrack: The purpose of this study is to obtain a description of the application of cooperative learning model type Numbered Heads Together (NHT) that can improve student learning outcomes in the Material Equation Square X Class IPA A SMA Negeri 1 Ampibabo. The type of research used is classroom action research (PTK) which refers to the design research of Kemmis and Mc. Taggart. Based on these results, it can be concluded that the application of NHT type cooperative learning model that can improve student learning outcomes on the matter of quadratic equations in class X IPA A SMA! Ampibabo, by following the following phases: (1) numbering, (2) asking questions or problems, (3) ask students to study, and (4) answered. Keywords: Type Numbered Heads Together, Learning Outcomes, Persamaan Kuadrat

Inverse Analysis of Cellulose by Using the Energy-Based Method and a Rotational Rheometer

Biological and polymer-type materials usually show a complicated deformation behavior. This behavior can be modeled by using a nonlinear material equation; however, the determination of coefficients in such a material equation is challenging. We exploit representation theorems in continuum mechanics and construct nonlinear material equations for cellulose in an oscillatory rheometer experiment. The material parameters are obtained by using the energy-based method that generates a linear regression fit even in the case of a highly nonlinear material equation. This method allows us to test different nonlinear material equations and choose the simplest material model capable of representing the nonlinear response over a broad range of frequencies and amplitudes. We present the strategy, determine the parameters for cellulose, discuss the complicated stress-strain response and make the algorithm publicly available to encourage its further use.

CONSTRUCTIVE ASPECTS OF STABILITY RESEARCH IN SPECIAL CASES

The method of stability research of the dynamic status of system described by the material equation resolved concerning derivatives with the linear summary differential operator, limited elements of the initial conditions system and the substantial basis of numerical methods and of methods of basic researches is offered.

Researches on a Class of Reaction-Diffusion Thermo-Plastic Material Equations

This paper deals with a class of hyperbolic thermo-plastic material equation. The equation includes a reaction-diffusion-taxis partial differential equation, a reaction-diffusion partial differential equation. In the actual course of the discussion, we append a motility term in the equation. Then, the existence of unique global strong solution is proved using the theory of fractional powers of analytic semi group generators to new equation.