Cross-Section Configuration Coefficient in the Zhurkov’S Generalized Equation

Постановка проблемы. Исследование долговечности строительных материалов с термофлуктуационной позиции является наиболее сложным, но и в тоже время наиболее адекватным методом. Ввиду того, что данная концепция является нечувствительной к изменениям физической структуры, возникает необходимость учета не только материала, но и конфигурации конструкции. Необходимо провести сравнение механизма разрушения при различных вариантах сечения для двух структурно отличающихся элементов - поливинилхлорида (ПВХ) и древесины. Результаты. Для элементов ПВХ и дерева составного сечения в два слоя без специальных связей получен одинаковый коэффициент k = 2. Для элементов составного сечения в три слоя без специальных связей получен коэффициент с интервалом k = 3,5…5,5, что требует дальнейшего уточнения. Выводы. На основе проведенного исследования теоретически обоснованы и экспериментально выявлены закономерности деформирования и разрушения ПВХ-элементов цельного сечения и составного сечения без специального соединения в два и три слоя. Определение термофлуктуационных зависимостей позволяет приблизить теоретические представления о работоспособности строительного материала в конструкции к реальным условиям. Statement of the problem. Studying the durability of construction materials in the aspect of thermal fluctuations is the most complicated, yet the most appropriate method. Considering that this concept does not take into account the changes of the physical structure, it becomes necessary to consider not the material alone but also the configuration of the structure. Therefore it is necessary to make a comparison of two structurally different elements - PVC and wood. Results. The coefficient of the 2-layer composite cross-section (no special connection) is the same for the PVC and wood elements: k = 2. The derived coefficient of the 3-layer composite cross-section (no special connection) is within the following range: k = 3,5…5,5, which requires a more precise definition. Conclusions. Based on the above experiment, we have theoretically established and experimentally confirmed the regularities of deformation and destruction of PVC elements of the 2 and 3-layer solid and composite cross-section without a special connection. Determining the thermal fluctuation relations allows us to bring theoretical concepts of the capacity of the construction material in a structure closer to actual conditions.

Local detailed balance

We review the physical meaning and mathematical implementation of the condition of local detailed balance for a class of nonequilibrium mesoscopic processes. A central concept is that of fluctuating entropy flux for which the steady average gives the mean entropy production rate. We repeat how local detailed balance is essentially equivalent to the widely discussed fluctuation relations for that entropy flux and hence is at most ``only half of the story.''

Quantum measurement arrow of time and fluctuation relations for measuring spin of ultracold atoms

The origin of macroscopic irreversibility from microscopically time-reversible dynamical laws—often called the arrow-of-time problem—is of fundamental interest in both science and philosophy. Experimentally probing such questions in quantum theory requires systems with near-perfect isolation from the environment and long coherence times. Ultracold atoms are uniquely suited to this task. We experimentally demonstrate a striking parallel between the statistical irreversibility of wavefunction collapse and the arrow of time problem in the weak measurement of the quantum spin of an atomic cloud. Our experiments include statistically rare events where the arrow of time is inferred backward; nevertheless we provide evidence for absolute irreversibility and a strictly positive average arrow of time for the measurement process, captured by a fluctuation theorem. We further demonstrate absolute irreversibility for measurements performed on a quantum many-body entangled wavefunction—a unique opportunity afforded by our platform—with implications for studying quantum many-body dynamics and quantum thermodynamics.

Fluctuation Relations for Dissipative Systems in Constant External Magnetic Field: Theory and Molecular Dynamics Simulations

We illustrate how, contrary to common belief, transient Fluctuation Relations (FRs) for systems in constant external magnetic field hold without the inversion of the field. Building on previous work providing generalized time-reversal symmetries for systems in parallel external magnetic and electric fields, we observe that the standard proof of these important nonequilibrium properties can be fully reinstated in the presence of net dissipation. This generalizes recent results for the FRs in orthogonal fields—an interesting but less commonly investigated geometry—and enables direct comparison with existing literature. We also present for the first time a numerical demonstration of the validity of the transient FRs with nonzero magnetic field via nonequilibrium molecular dynamics simulations of a realistic model of liquid NaCl.