Principles Of Mechanics Research Articles

Influence of fire severity and concrete properties on the thermo‐hygral behavior of concrete during fire exposure

AbstractSince the world is transitioning toward performance based design, the study of thermo‐hygral behavior of concrete when subjected to real fire becomes crucial. Fire accidents have revealed that nominal fire curves cannot be applied because of varying severity of real fire. In 2008, traveling fire concept was developed in which severity is dependent on heat release rate and fire size. This study explores the effect of fire severity and other concrete properties like strength, aggregate type, and relative humidity. The proposed model has been developed by combining the principles of mechanics and thermodynamics and upon validation with the experimental results, a reasonable agreement has been observed. It can be concluded that severity of fire is directly related to thermo‐hygral behavior of concrete. On the other hand, this study also highlights the influence of type of aggregate and moisture content in addition to the traditional variables like volume fraction of solid and permeability. On studying the influence of type of aggregate, it can be concluded that recycled aggregate concrete performed better than conventional concrete. The integration of proposed model in the performance based design is a leap toward development of resilient structure subjected to dynamic fire conditions.

Geomechanics and Geology of Marine Terraces of the Crotone Basin, Calabria (Italy)

This study investigates the geomechanical behavior of five terrace orders in the Crotone Basin. The purpose is to understand the physical–mechanical parameters of these terraces to determine whether rock or soil mechanics principles should be applied for stability analysis. Samples were collected from each terrace following an extensive field survey. Laboratory analyses were conducted to measure pulse velocities, uniaxial unconfined compressive strength, and compressive strength with truncated conical platens. The findings revealed key physical–mechanical parameters of the rocks, which are crucial for stability assessments. The Crotone Basin, known for its mineral resources such as hydrocarbons and rock salts, has been studied geologically since before the 1950s, but there is a lack of geomechanical data in existing literature. Therefore, the results presented here are novel and provide a basis for future studies on the instability of rocky slopes composed of similar soft rock types. These results will aid in accurate geological–geotechnical model reconstructions. While the findings can be applied to similar cases, it is important to note that each analysis site, despite showing similar phenomena, is unique and requires individual investigation.

ИСТОРИКО-ПРАВОВОЙ АСПЕКТ ИНСТИТУТА МЕЖДУНАРОДНОГО МИРОТВОРЧЕСТВА

The article provides a retrospective analysis of the genesis of the Institute of international peace-keeping. The works of philosophers, politicians and public figures are considered in this article. The above-mentioned persons have made a significant contribution to the development of the idea of in-ternational peacemaking. The rudiments of the regulatory framework of the first international treaty are analyzed, which considered the principles of international peacekeeping and mechanisms for the prevention of military conflicts. The conclusion is formulated that the genesis of the Institute of inter-national peacemaking began with the ideas of scientists, politicians and philosophers about peace and cooperation, developed through the creation of the first international organizations and peaked with the founding of the United Nations, which became the central forum for coordinating efforts to maintain peace and security in the world community.

Predicting the translation efficiency of messenger RNA in mammalian cells.

The degree to which translational control is specified by mRNA sequence is poorly understood in mammalian cells. Here, we constructed and leveraged a compendium of 3,819 ribosomal profiling datasets, distilling them into a transcriptome-wide atlas of translation efficiency (TE) measurements encompassing >140 human and mouse cell types. We subsequently developed RiboNN, a multitask deep convolutional neural network, and classic machine learning models to predict TEs in hundreds of cell types from sequence-encoded mRNA features, achieving state-of-the-art performance (r=0.79 in human and r=0.78 in mouse for mean TE across cell types). While the majority of earlier models solely considered 5' UTR sequence, RiboNN integrates contributions from the full-length mRNA sequence, learning that the 5' UTR, CDS, and 3' UTR respectively possess ~67%, 31%, and 2% per-nucleotide information density in the specification of mammalian TEs. Interpretation of RiboNN revealed that the spatial positioning of low-level di- and tri-nucleotide features (i.e., including codons) largely explain model performance, capturing mechanistic principles such as how ribosomal processivity and tRNA abundance control translational output. RiboNN is predictive of the translational behavior of base-modified therapeutic RNA, and can explain evolutionary selection pressures in human 5' UTRs. Finally, it detects a common language governing mRNA regulatory control and highlights the interconnectedness of mRNA translation, stability, and localization in mammalian organisms.

Variability in the measured soil‒water characteristic curve with respect to the numbers of specimens

The soil‒water characteristic curve (SWCC) defines the relationship between the amount of water in soil and soil suction. The SWCC is commonly used to estimate the hydraulic conductivity function (HCF) and the shear strength function (SSF). Therefore, an accurate determination of the SWCC is crucial for implementing the principles of unsaturated soil mechanics. The SWCC is commonly determined from a limited number of experimental data because SWCC measurements are time-consuming and costly. As a result, the minimum number of required soil specimens is crucial for a SWCC test when considering the accuracy of the determined SWCC and the experimental expenses. In this study, both engineered from sand and kaolin mixtures and residual soils from Bukit Timah Formation in Singapore are selected to prepare soil specimens for SWCC measurements. The SWCCs obtained from the specimens with engineered soil are consistent, while those from specimens with residual soil are slightly scattered. This indicates that one specimen is sufficient to determine the SWCC for engineered soil samples, while a minimum of two specimens should be prepared for the determination of SWCC for residual soil samples from Bukit Timah Formation.

Modeling of the Particle Abrasion Process and a Discrete Element Method Study of Its Shape Effect.

This study introduces a novel method for particle abrasion derived from fundamental natural phenomena and mechanical principles, allowing precise control over the degree of abrasion and more accurately mimicking natural processes. The method's validity is confirmed using a specific shape index. Through conventional triaxial tests, the mechanical behavior of granular aggregates with varying degrees of abrasion was analyzed. The findings indicate that increased particle abrasion leads to a decrease in the average coordination number and sliding amount, while the rotation amount increases. This suggests an inverse relationship between the degree of abrasion and the structural stability and interlocking of the particle aggregate. The fabric anisotropy of the system is mainly attributed to the anisotropy of the contact normal force, which decreases as particle abrasion increases. The partial stress ratio of the particle system is influenced by fabric anisotropy and remains independent of particle shape. Additionally, the internal friction angle may be overestimated in conventional triaxial tests.

State-of-the-art analysis of quantum cryptography: applications and future prospects

Quantum computing provides a revolution in computational competences, leveraging the principles of quantum mechanics to process data in fundamentally novel ways. This paper explores the profound implications of quantum computing on cryptography, focusing on the vulnerabilities it introduces to classical encryption methods such as RSA and ECC, and the emergence of quantum-resistant algorithms. We review the core principles of quantum mechanics, including superposition and entanglement, which underpin quantum computing and cryptography. Additionally, we examine quantum encryption algorithms, particularly Quantum Key Distribution (QKD) protocols and post-quantum cryptographic methods, highlighting their potential to secure communications in the quantum era. This analysis emphasizes the urgent need for developing robust quantum-resistant cryptographic solutions to safeguard sensitive information against the imminent threats posed by advancing quantum technologies.

The Multi-Modal Robot Perception, Language Information, and Environment Prediction Model Based on Deep Learning

This paper presents a deep learning-based model to enhance robot perception and prediction in complex environments. The model utilizes CNN, LSTM, and attention mechanisms to address multimodal perception and environment prediction tasks. The introduction provides background on the importance of robots in various fields and emphasizes the need for multimodal perception. The methodology section explains the working principles of CNN, LSTM, and attention mechanisms. The experimental results demonstrate significant improvements in robot perception and prediction, with low errors and high accuracy. The proposed model supports robot applications in complex environments such as autonomous navigation and human-robot interaction. It effectively handles multimodal data and enhances robot perception and prediction capabilities. The experimental results validate the model's effectiveness, providing important support for robot decision-making in complex environments.

Intensity-Product-Based Optical Sensing to Beat the Diffraction Limit in an Interferometer.

The classically defined minimum uncertainty of the optical phase is known as the standard quantum limit or shot-noise limit (SNL), originating in the uncertainty principle of quantum mechanics. Based on the SNL, the phase sensitivity is inversely proportional to K, where K is the number of interfering photons or statistically measured events. Thus, using a high-power laser is advantageous to enhance sensitivity due to the K gain in the signal-to-noise ratio. In a typical interferometer, however, the resolution remains in the diffraction limit of the K = 1 case unless the interfering photons are resolved as in quantum sensing. Here, a projection measurement method in quantum sensing is adapted for classical sensing to achieve an additional K gain in the resolution. To understand the projection measurements, several types of conventional interferometers based on N-wave interference are coherently analyzed as a classical reference and numerically compared with the proposed method. As a result, the Kth-order intensity product applied to the N-wave spectrometer exceeds the diffraction limit in classical sensing and the Heisenberg limit in quantum sensing, where the classical N-slit system inherently satisfies the Heisenberg limit of π/N in resolution.

A new device and calibration method for the fracture energy testing of single-particle impact

This study presents a piezoelectric fast load cell (PFLC) as a novel device for testing single particle fracture energy under impact and proposes a collision model for measurement and calibration. The research examined various models, modifying the long-rod model to create a more practical short-rod model describing the contact dynamics during collision processes. Through back-calculating the Young's modulus of glass beads, the optimized measurement settings are calibrated for practical use based on the short-rod model, which is corroborated by comparison with fracture probabilities obtained from the drop weight tests and PFLC. It was verified that the observed fracture characteristics of ore align with established principles of fracture mechanics, validating the testing approach. The PFLC offers a cost-effective and compact substitute to classic ultra-fast load cell (UFLC), potentially enhancing the adoption of advanced comminution models like the Tavares Model.

Analysis of Mechanical Damage in Dance Training Under Artificial Intelligence Behavior Constraints

This study focuses on the application of artificial intelligence behavior constraints in the analysis of mechanical injuries in dance training, aiming to accurately analyze and effectively prevent mechanical injuries during dance training through the introduction of artificial intelligence technology. Dance, as a highly dependent art form on physical skills, often comes with a certain risk of mechanical injury during its training process. In this study, we first reviewed the relevant theories of mechanical injuries in dance training and analyzed the inherent relationship between dance movements and mechanical injuries. Subsequently, we utilized artificial intelligence technology to conduct behavior constraint analysis on the dance training process. By constructing a dance action recognition model, we achieved real-time monitoring and evaluation of dance training actions. On this basis, we further utilize the principles of mechanics to quantitatively analyze dance movements and extract key factors that affect mechanical damage. Through in-depth analysis and comparison, this study found that mechanical injuries in dance training are mainly influenced by various factors such as movement standardization, training intensity, and individual differences. We applied the theory of sports biomechanics to study sports dance injuries and analyzed the causes of athlete injuries. By exploring more scientific training methods and means, the correlation coefficients between main joint muscle strength, proprioception, tibialis anterior muscle imbalance response time, and rotational stability were measured to study proprioception training suitable for sports dance, adhering to the principle of gradual progression. In future sports dance rotation training, corresponding training should be carried out according to the characteristics of different rotation steps, providing reference for strengthening leg training and ankle training.

Design of plastering device of plastering machine

Abstract The plastering machine can effectively improve the plastering efficiency, and the plastering process mainly includes filling the mortar, plastering, floating mortar, and compacting mortar. All of these function is completed by a plastering device. The diversity and complexity of the device increase the production cost and the weight of the whole machine. In order to guarantee the plastering quality and optimize the institution, this thesis designs a plastering device that integrates mortar supply, plastering, surface flattening, and compacting functions. The working process of the plastering mechanism includes upward plastering and downward flattening, mainly achieved by the rotation motion of the hopper. The contour shape of the hopper was designed using the principle of cam mechanism, and the upward plastering and self-locking of the hopper after reaching the top were designed using the principle of connecting rod mechanism. The hopper is supported by two pneumatic springs. The flipping force of the pneumatic springs during the upward plastering and downward plastering processes was analyzed and calculated, which provides the basis for choosing the power of the driving motor.

Selective detection of MnO4- in non-standard explosives by nitrogen-doped carbon quantum dots-copper complexes (NCQDs@Cu)

Nitrogen-doped carbon quantum dots (NCQDs) with bright yellow fluorescence (quantum yield of 27.3 %) were synthesized via a solvothermal method using 2,3-diaminopyridine as the carbon and nitrogen source and ethanol as the solvent. Subsequently, the NCQDs were reacted with Cu2+ in an aqueous solution, forming nitrogen-doped carbon quantum dots-copper complexes (NCQDs@Cu) with great potential for selective determination of MnO4- ions. The aqueous solution of NCQDs@Cu exhibiting a very weak fluorescence (quantum yield of 2.2 %) demonstrated a significant enhancement (quantum yield of 10.0 %) upon interaction with MnO4-(Turn-on). Furthermore, this enhancement remained unaffected by the interfering conventional or unconventional explosives, inorganic ions, and oxidants. Moreover, a good linear relationship existed between the fluorescence intensity of the NCQDs@Cu and the concentration of the permanganate ions in a range of 0 to 5 μmol/L with a detection limit of 32.4 nmol/L. Additionally, the study investigated the underlying principles of the detection mechanism using advanced technologies such as X-ray photoelectron spectroscopy(XPS), The Fourier-transform infrared (FTIR), ultraviolet visible spectrometer (UV–Vis), fluorescence spectrometer and other methods. Finally, the NCQDs@Cu were successfully applied for detecting MnO4- in simulated and actual unconventional explosives, demonstrating a good correlation with standard methods. Therefore, the developed NCQDs@Cu can be used for rapid on-site inspection in explosive incident scenarios. This new method of using carbon dots-metal complexes as fluorescent probes will also provide new ideas for researchers.

Synthetic, self-oscillating vocal fold models for voice production researcha).

Sound for the human voice is produced by vocal fold flow-induced vibration and involves a complex coupling between flow dynamics, tissue motion, and acoustics. Over the past three decades, synthetic, self-oscillating vocal fold models have played an increasingly important role in the study of these complex physical interactions. In particular, two types of models have been established: "membranous" vocal fold models, such as a water-filled latex tube, and "elastic solid" models, such as ultrasoft silicone formed into a vocal fold-like shape and in some cases with multiple layers of differing stiffness to mimic the human vocal fold tissue structure. In this review, the designs, capabilities, and limitations of these two types of models are presented. Considerations unique to the implementation of elastic solid models, including fabrication processes and materials, are discussed. Applications in which these models have been used to study the underlying mechanical principles that govern phonation are surveyed, and experimental techniques and configurations are reviewed. Finally, recommendations for continued development of these models for even more lifelike response and clinical relevance are summarized.

Effect of extrusion cooking on physical and thermal properties of instant flours: a review

The production of instant flour constitutes a fast-expanding sector, and, this is an innovative area, that is being modified adjusting continually its methodologies to enhance production efficiency, optimizing its resources, fostering innovation in its applications, and increasing its economic income. Among the methods widely cited for precooked flours production are spray drying, drum drying, and extrusion cooking, the latter emerging as a high-potential and versatile solution to produce such commodities. In this regard, a comprehensive understanding of the extrusion process, its mechanical principles, and its effects on the physical characteristics of extruded raw materials is necessary. Analyzing process parameters (specifical mechanical energy and mean residence time) is essential to achieve the desired outcomes. Furthermore, it was analyzed the effect of the process modification conditions (temperature, screw speed, and moisture content) on the physical characteristics of the extruded instant flours. This review offers insights into the most reported system parameters as Specifical Mechanical Energy (SME), Pressure, Torque and, physical properties assessed in different instant flour obtained by extrusion such as Water Absorption Index (WAI), Water Solubility Index (WSI), Swelling Power (SP), Rehydration Capacity, Wetting Capacity, Sinking, Dispersibility, Pasting properties, Thermal properties, and Color. The review summarized and discussed the behavior of the hygroscopic properties and the water affinity of different instant flours obtained by extrusion.

Mechanical Behavior of Frozen Soil Subjected to Freeze–Thaw Cycle Under Cyclic Impact Load and Passive Confining Pressure

In this study, the effects of freeze–thaw cycles and cyclic impacts on frozen soil were systematically investigated. With an increase in the number of freeze–thaw cycles, the peak stress of frozen soil decreased until a stable state was achieved. Moreover, subjecting frozen soil to an increased number of cyclic impacts led to notable alterations in mechanical characteristics, including peak stress, critical strain and dynamic elasticity modulus. Both the freeze–thaw cycles and cyclic impacts were identified as primary damage mechanisms in understanding frozen soil degradation processes. Damage resulting from these impacts conformed to the Weibull distribution pattern. Damages induced by freeze–thaw cycles, individual impacts and cyclic impacts were integrated into the Zhu–Wang–Tang viscoelastic model (ZWT model). Relying on principles of elastic mechanics, the role of confining pressure on frozen soil was examined and subsequently integrated into an improved ZWT model. To evaluate the model’s effectiveness, its predictions were compared with experimental results.

Design of 2-DOF Thrust vector control system for Rockets and Missiles

This paper outlines the development and implementation of a Thrust Vector Control (TVC) system tailored specifically for solid propellant rocket engines, aimed at enhancing the portability of hybrid and liquid propellant rocket systems. The proposed system ensures trajectory stability and rapid response to flight emergencies by effectively addressing external perturbations like wind. Key components are Gyroscopic (GYRO) sensors, good micro-controller, and Servo motors, collectively referred to as Thrust vectoring components, which dynamically adjust thrust direction opposite to the rocket's trajectory to maintain stability. Drawing from an extensive literature review analyzing existing TVC system designs, with a focus on thrust characteristics and engine combustion timings, the design integrates considerations of geometric properties, kinematics, forces, energy requirements, safety, cost, and control methods, aligning with both mechanical and avionic design principles. The anticipated outcome is an advancement in rocket propulsion technology, characterized by improved angular speed control, trajectory linearity, and rapid response capabilities.

How Well Can Quantum Embedding Method Predict the Reaction Profiles for Hydrogenation of Small Li Clusters?

Quantum computing leverages the principles of quantum mechanics in novel ways to tackle complex chemistry problems that cannot be accurately addressed using traditional quantum chemistry methods. However, the high computational cost and available number of physical qubits with high fidelity limit its application to small chemical systems. This work employed a quantum-classical framework which features a quantum active space-embedding approach to perform simulations of chemical reactions that require up to 14 qubits. This framework was applied to prototypical example metal hydrogenation reactions: the coupling between hydrogen and Li2, Li3, and Li4 clusters. Particular attention was paid to the computation of barriers and reaction energies. The predicted reaction profiles compare well with advanced classical quantum chemistry methods, demonstrating the potential of the quantum embedding algorithm to map out reaction profiles of realistic gas-phase chemical reactions to ascertain qualitative energetic trends. Additionally, the predicted potential energy curves provide a benchmark to compare against both current and future quantum embedding approaches.

Research on the Mechanism of the Skidding Device of Bulk Grain into Silo

In the field of handling, storage and transportation, chutes are used to transfer bulk solids between conveyors and warehouses. In these systems, traditional analytical methods based on the principles of continuum mechanics approximate an accelerated flow that contains the physical body solid properties obtained from standardized tests. Because it is difficult to physically observe the flow inside the transfer structure, there have been few studies to validate the method at full scale. In contrast, discrete element modeling (DEM) allows flow visualization through a transfer chute and qualitative and quantitative analysis if accurate simulation parameters are selected. In order to adapt to the needs of modern intelligent warehousing, we reduced the grain crushing and damage in the process of grain storage. To design and investigate the motion performance of grain particles in a sliding dustpan, this paper utilizes rocky simulation technology, combined with the corresponding bench experiments, to study the impact of the angle arrangement of the dustpan, and to verify the results of the simulation analysis based on the stress–strain analysis of the particle impact. It was found that when the angle of the dustpan arrangement was 40 degrees, the flow of all particles had a better performance in terms of pass ability and energy loss. In the continuous cycle obtained from the simulation, the particle group state at each moment is almost the same as the particle characteristics in the experiment, indicating that the angle of the bucket has an effect on the particle permeability. In this paper, the results of the study on the state of the grain group on the silo device will provide a useful reference for the design of a grain silo device.

Size effect analysis of mode I fracture performance of hot mix asphalt

The diameters of asphalt concrete cylindrical specimens typically measure either 100 mm or 150 mm, as these are the standard sizes for almost all conducted tests. However, the impact of specimen size on the fracture performance of asphalt mixtures has not been extensively explored. This study aimed to address this gap by performing laboratory tests on semi-circular bending (SCB) specimens. These tests were designed to apply the Size Effect Law (SEL) in evaluating the fracture performance of two asphalt mixture types (AC10 and AC16) at −10 ℃. The experiment selected four different diameters (76 mm, 100 mm, 125 mm, and 150 mm) and two notch-radius ratios (α0 = 0.2 and 0.4) to investigate the relationship between the specimen dimensions and both the nominal stress and fracture toughness (KIC). Results indicated that the nominal stress and KIC adhered to the SEL. It was observed that both aggregate gradation and notch-radius ratio (α0) significantly influenced the SEL’s effect on nominal stress. An increase in α0 from 0.2 to 0.4 shifted the fracture failure towards a more linear elastic fracture behavior. Specifically, the coarser gradation in AC16, compared to AC10, predisposed the fractures towards linear elastic behavior. Moreover, an increase in α0 notably augmented the brittleness number. For specimens with identical dimensions and α0, AC16 exhibited higher D/D0 values, indicating a stronger alignment with Linear Elastic Fracture Mechanics (LEFM) principles for the tested specimen sizes compared to AC10. As the size of the specimen increased, there was a gradual rise in KIC, with the enlargement from 76 mm to 150 mm resulting in KIC increases of 25.2 % and 12 % for α0 values of 0.2 and 0.4, respectively, in the AC10 mixture. Conversely, the AC16 mixture saw respective enhancements of 15.8 % and 7.6 % for the same α0 values. The influence of α0 on the apparent fracture toughness became less pronounced with its increase; KIC gradually decreased for AC10, yet increased for AC16 with rising α0 levels. For the same asphalt mixture type, KIC was found to escalate with both D/D’0 and α0. At an α0 of 0.4, the disparities between KIc and KIcm, – expressed as (KIcm- KIc)/ KIcm, – stood at 13.9 % and 9.2 % for AC10 and AC16, respectively, with a diameter of 150 mm. Based on these findings, it is recommended to utilize an SCB specimen with a diameter of 150 mm and an α0 of 0.4 for fracture performance testing, as these parameters appear to provide the reliable assessment of the materials’ fracture behavior.