Dynamic Analysis Research Articles

A study on a physical based manoeuvring mathematical model for submarines

The manoeuvrability of submarines is one of the important factors from mission and safety points of view. In particular, manoeuvring motions with a large drift angle and/or angle of attack in both the horizontal and the vertical planes have different motion parameters compared to the normal manoeuvring motions. To evaluate the manoeuvrability during these types of particular motions of submarines, especially at the initial design stage, the manoeuvring hydrodynamic derivatives that are related to various manoeuvring motions must be identified.Karasuno model, which is termed a physical based model, has the advantages that it needs only model experiments for drift motion and it can provide greater accuracy under motion with large angles. Despite these advantages, this model has not been applied to other vessels excluding fishing vessels. The applicability of this method to submarines therefore should be examined. The applicability of Karasuno model for submarines is validated through a computational fluid dynamics (CFD) analysis and comparisons with experimental data in this work. The findings contribute to identifying the manoeuvring hydrodynamic forces for submarines and evaluating their manoeuvring performance. Through rigorous validation, the potential of the proposed model as a reliable tool for predicting and analyzing submarine maneuvering motions is demonstrated.

The influence of length under blast load on the propagation mechanism of interconnected cracks

In order to study the influence of interconnected defects on the rock breaking effect under blast load, the relevant explosion experiment was carried out by prefabricating interconnected cracks on plexiglass plates (PMMA), and the propagation mechanism of interconnected cracks under blast load was studied from the length level. The dynamic caustic line system and finite element analysis software were combined to analyze the stress intensity factor, propagation velocity of the interconnected crack tip, and full-field stress of the specimen; the results show that with the radial stress wave propagation direction as the axis of symmetry, the two interconnected cracks with symmetrical angles but different lengths are under the action of blast load; there is a certain competition between the two cracks; the longer cracks are more likely to initiate and propagate, and the shorter cracks almost do not propagate. In addition, in terms of energy accumulation at the tips of the two cracks, the longer crack has a certain inhibitory effect on the shorter crack, and when the length of the longer crack remains unchanged, the inhibition effect weakens with the increase of the length of the shorter crack, and when the length of the shorter crack remains unchanged, the inhibitory effect increases with the increase of the length of the longer crack. After the crack initiation of the longer crack, the relationship curve between the stress intensity factor and the crack propagation velocity and time of the longer crack tip decreases first, and then the relationship curve rises to the peak as the energy of the tip of the shorter crack is transferred to the longer crack, and then the oscillation decreases, while the stress intensity factor and crack propagation rate of the shorter side crack tip show an overall downward trend. The numerical simulation is used to supplement the analysis of the stress propagation in the full-field of the specimen, which corroborates with the experiment results. The experimental study provides a theoretical basis for the analysis of the propagation mechanism of interpenetrating cracks under blast load in practical engineering.

Effect of Ni-RGO nanosheets on the creep behavior of Sn–Ag–Cu composite solder joints

Creep damage of Sn–Ag–Cu micro-joints is inevitable in service, even at room temperature. In this study, Ni-decorated reduced graphene oxide (Ni-RGO) nanosheets were rationally selected as a promising reinforcement in Sn-3.0Ag-0.5Cu (SAC305) solder to improve creep resistance. Tensile creep tests were conducted on the Ni-RGO reinforced SAC305 micro-joints under 8–14 MPa stress at 100–150 °C by dynamic mechanical analysis (DMA) equipment. Micrography and fractography were observed using FESEM. The stress exponent (n) increased from 5.83 to 6.37, and the activation energy (Q) rose from 68.80 to 75.41 kJ/mol as 0.10 wt% Ni-RGO nanosheets were added into the SAC305 solder, indicating the occurrence of diffusion mechanism. By adding a trace amount of Ni-RGO nanosheets (no more than 0.10 wt%), the crack initiation was prone to occur at the wave-valley of the continuous scallop shaped interface, where the diffusion of vacancies occurred, resulting in hybrid-fracture features of quasi-cleavage and dimples. It can be concluded that the inclusion of trace amounts of Ni-RGO nanosheets can enhance the creep resistance of SAC305 micro-joints during service.

Surface modification strategies for improved cellulose nanocrystal integration in 3D-Printed bio-based acrylate matrix

The current application of renewable resources in vat photopolymerization (VP) 3D printing is rather limited, emphasizing the importance of incorporating bio-based materials into additive manufacturing (AM). In this study, VP 3D printing technology was applied to create composites (derived from soybean oil-based resin) reinforced with cellulose nanocrystals (CNC). Two distinct modifications for CNC, i.e., the acrylation and functionalization with methyl methacrylate, were selected to achieve strong bonding with the UV-curable acrylate matrix. With the use of 0.1 wt% of modified CNC, the resins retain remarkable performance and support the creation of high-resolution prints. The successful integration of modified CNC showed significant improvements in tensile and flexural properties, e.g., elongation at break increased by 75 % and 295 %, respectively. The addition of modified CNC fillers also increased tensile strength by 147 % and flexural strength by 121 %. Fourier-transformation infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA) testified to the enhanced interface between filler and matrix. The morphological features and print quality were examined with microscopic analysis, UV-VIS spectroscopy, and colorimetry. The resin showed exceptional printing resolution, characteristic of VP printing, and yielded double bond conversion rates greater than 70 %. The findings presented here indicate that the addition of 0.1 wt% of modified CNC to bio-based resins results in an exceptional increase in the mechanical performance and dimensional stability of printed materials.

Reconsidering Museums’ Climate and Seasonal Adjustment for Vulnerable Artifacts

ABSTRACT The paper provides new experimental evidence for vulnerable artifacts on the dependence of failure strain on the loading rate corresponding to typical environmental loads lasting between hours and months. Animal glue-based ground was chosen for this study as an easily available, hygroscopic and brittle material as well as due to its abundance in collections and its relevance when discussing the risk of mechanical damage to objects. Gesso specimens were tested using dynamic mechanical analysis and tensile testing at different frequencies, under a variety of loading rates and temperatures. The time-temperature superposition principle was used to predict the material response to slow deformations (lasting hours to months) that are otherwise inaccessible on laboratory timescales. The results demonstrate that brittle materials such as animal glue-based grounds do not benefit from longer cycles of applied loads as failure strain is not time-dependent within the investigated timescale.

Experimental investigation on the thermal characteristics of Kevlar/hemp intraply hybrid composites: Influence of various weaving designs

In this work, several weaving designs of intra-ply woven fabric Kevlar/hemp fiber (KHE) reinforced epoxy hybrid composites are developed and their thermal characteristics are examined. Thermogravimetric analysis showed that intra-ply hybrid of plain and basket weave designs possessed highest thermal stability. The different weaving patterns of KHE hybrid composites have no effect on the glass transmission temperature (Tg) value as inferred from the differential scanning calorimetry results. The thermomechanical analysis clearly demonstrates the superior dimension stability of the hybrid composites with basket weave. Dynamic mechanical analysis reveals that twill weave KHE have exhibited the maximum storage modulus (2021 MPa), loss modulus (210 MPa) and lower tan delta (0.3090) values compared to all other composites. Based on the obtained results, it is denoted that all the fabricated KHE hybrid composites displayed improved thermal performance. It may be suitable for applications in thermal insulation panels, fire-resistant clothing, and automotive underbody shields.

Olfactory sampling volume for pheromone capture by wing fanning of silkworm moth: a simulation-based study

Odours used by insects for foraging and mating are carried by the air. Insects induce airflows around them by flapping their wings, and the distribution of these airflows may strongly influence odour source localisation. The flightless silkworm moth, Bombyx mori, has been a prominent insect model for olfactory research. However, although there have been numerous studies on antenna morphology and its fluid dynamics, neurophysiology, and localisation algorithms, the airflow manipulation of the B. mori by fanning has not been thoroughly investigated. In this study, we performed computational fluid dynamics (CFD) analyses of flapping B. mori to analyse this mechanism in depth. A three-dimensional simulation using reconstructed wing kinematics was used to investigate the effects of B. mori fanning on locomotion and pheromone capture. The fanning of the B. mori was found to generate an aerodynamic force on the scale of its weight through an aerodynamic mechanism similar to that of flying insects. Our simulations further indicate that the B. mori guides particles from its anterior direction within the ~ 60° horizontally by wing fanning. Hence, if it detects pheromones during fanning, the pheromone can be concluded to originate from the direction the head is pointing. The anisotropy in the sampling volume enables the B. mori to orient to the pheromone plume direction. These results provide new insights into insect behaviour and offer design guidelines for robots for odour source localisation.

Kinetics prediction of normal knee and undergone total knee arthroplasty during squatting based on extreme gradient boosting

Following an arthroplasty, biomechanical evaluation of the knee joint is crucial because it plays a significant role in patient rehabilitation and physician follow-up. The sixty-two subjects, consisting of 31 with normal knees and 31 who had undergone total knee arthroplasty, evaluated the kinetics of the knee joints during squatting using inverse dynamics analysis. Artificial intelligence based on the XGBoost model was also used to predict kinetics data during group squatting. The result revealed that the maximum force, moment, and quadriceps force in the normal knee were higher than in the TKA group during squatting. The maximum resultant joint force magnitude in the normal and TKA groups revealed an average of 4.35 ± 1.00 and 3.08 ± 1.20 times body weight, respectively. Kinetics of the knee joint in a normal knee significantly differed (p < 0.05) from undergoing TKA, especially in the AP-direction force. Additionally, the resultant moment that included the quadriceps muscle force in the normal group was higher than in the TKA groups. The extreme gradient boosting algorithm (XGBoost) model has prediction performance metrics, which are considered to have high correlation performance in the case of kinetics.

Dynamic analysis of planetary gear transmission based on Lagrange interpolation polynomials

Abstract This paper proposes a novel dynamic model considering manufacturing errors and eccentricity errors to analyze the dynamics of planetary gear transmission (PGT). The dynamic model is established based on the fractional-order calculus (FOC) and solved by an enhanced fourth-order Lagrange interpolation polynomials (LIP) method. Three numerical examples and the vibration experiments of planetary gear transmission are employed for verification. The comparison results indicate that the proposed solution method has higher solution accuracy and efficient than the existing algorithms in solving fractional equations, and the relative errors of the proposed solution method in three examples are 0.32%, 0.78% and 0.16%, respectively. The proposed dynamic model of PGT has better agreement with the experimentally measured signal compared with the integer-order dynamic model, and the maximum error and average error of the characteristic frequency amplitude between the proposed dynamic model and the measured signal are 4.76% and 3.57%, respectively. The proposed method contributes to the theoretical foundation for the signal monitoring of PGT.

Exhaustive Enumeration of Spatial Prime Structures

Prime structures are link chains with 0 DoF (degrees of freedom), not including subchains with 0 or fewer DoF, which are expected to be used in systematic kinematic and dynamic analyses of link mechanisms. This paper describes the exhaustive enumeration of spatial prime structures with three–five links. There will be more types of spatial prime structures than planar prime structures due to the variety in the DoF of kinematic pairs and the existence of prime structures with idle DoF. In the enumeration, the graphs which represent the connection of links and pairs are used. The vertices of the graphs represent the links of structures, and the edges represent the kinematic pairs. To consider the pair DoF, weights are set on edges. First, the numbers of pairs are calculated using Grübler’s equation. Second, the graphs corresponding to structures are enumerated, without considering pair DoF, and the isomorphic graphs and other inappropriate graphs are eliminated. Then, the combinations of pair DoF arrangement are enumerated, and the isomorphic graphs and graphs which correspond to non-prime structures are eliminated. Finally, prime structures with idle DoF are considered. As a result, 3, 13, and 97 kinds of spatial prime structures for 3, 4, and 5 links, respectively, are obtained.

A Dynamic Analysis of a Poly-Articulated Robot

A Dynamic Analysis of a Poly-Articulated Robot

Dynamic Analysis of Physiological and Biochemical Substances in Two Types of Root Type Alfalfa during Overwintering Period

Dynamic Analysis of Physiological and Biochemical Substances in Two Types of Root Type Alfalfa during Overwintering Period

Kinetic analysis and stability evaluation of femoral neck fracture with internal fixation based on gait rehabilitation training

To explore the biomechanical effects of different internal fixation methods on femoral neck fractures under various postoperative conditions, mechanical analyses were conducted, including static and dynamic assessments. Ultimately, a mechanical stability evaluation system was established to determine the weights of each mechanical index and the evaluation scores for each sample. In static analysis, it was found that the mechanical stability of each model met the fixation requirements post-fracture. During the healing process, the maximum stress on the hollow nail slightly increased, and stress distribution shifted from multi-point to a more uniform single-point distribution, which contributes to fracture healing and reduces the risk of stress concentration. In dynamic analysis, resonance points frequently occurred at low frequencies. With increasing walking speed, the maximum stress increased significantly. At slow speeds, the maximum stress approached the material's yield limit. Under cyclic dynamic loading, the number of cycles barely met the requirements of the healing period, and increasing walking speed may lead to fatigue fractures. The evaluation model established in this study comprehensively considers different mechanical performances in static and dynamic analyses. Based on various mechanical analyses and evaluation systems, the applicability of internal fixation treatment plans can be assessed from multiple dimensions, providing the optimal simulated mechanical solution for each case of femoral neck fracture treatment.

Dynamic time warp of emotions in patients with cutaneous T-cell lymphoma treated with corticosteroids

BackgroundA substantial number of patients treated systemically with synthetic glucocorticoids undergo emotional disturbances during treatment. Patients with cutaneous T-cell lymphoma frequently experience skin inflammation and itching and often require glucocorticoid treatment. ObjectiveThis case-series study aimed to examine how emotional and skin-related symptoms interact throughout glucocorticoid treatment. MethodsFive cutaneous T-cell lymphoma patients undergoing systemic glucocorticoid treatment completed daily ecological momentary assessments for on average 30 assessments. Fluctuations in their emotions and symptoms were analyzed using undirected and directed dynamic time warp analyses, and were visualized in symptom networks. ResultsTowards the end of the glucocorticoid treatment, a decline was found in positive psychological symptoms. Idiographic dynamic time warp analyses revealed highly variable symptom networks. Directed time-lag group-level analyses revealed irritability, enthusiastic, and excited as variables with highest outstrength, in which mainly decreasing levels of positive emotions were associated with a higher likelihood of experiencing increases in itchy skin and skin problems the next day. ConclusionThe end of glucocorticoid treatment, potentially via the induction of hypocortisolism, seems to coincide with decreased energy, motivation, and enthusiasm. Itch and skin problems could be a consequence of low positive emotions the day before.

Dynamic elicitation and forecasting innovation requirement of smart product-service system via user-manufacturer value co-creation perspective using multi-source data

Achieving greater efficiency and lower resource consumption is a constant pursuit for successfully developing smart product-service system (PSS). Conducting dynamic requirements analysis is increasingly important in the process while the value co-creation of smart PSS stakeholders has not been sufficiently considered. This study adopts a user-manufacturer value co-creation perspective to explore smart PSS dynamic requirement elicitation and forecasting. Using multi-source data of user online reviews, historical descriptive texts and patent abstracts, this study dynamically elicits the smart PSS innovation requirements using dynamic topic model (DTM) and bidirectional encoder representation from transformers (BERT). Furthermore, the key innovation requirements of smart PSS are identified by integrating their importance and satisfaction values into a dynamic importance-performance analysis (DIPA). Then, the trend of smart PSS key innovation requirements is predicted by the grey forecasting model to determine the smart PSS improvement direction. An empirical study of smartwatch service system is conducted to validate the proposed approach. By blending both user and manufacturer requirements, this study provides a novel framework for dynamic requirement elicitation and forecasting of smart PSS based on multi-source data. It contributes to facilitating the value co-creation during smart PSS development to optimize manufacturer’s R&D resource allocation and enhance user experience.

Uncovering the key features of iron metabolism in Pakistan from 2005 to 2020: A dynamic material flow analysis

Iron is a crucial metal for Pakistan's growth, especially in its infrastructure and industrial sectors. However, the key features of iron metabolism are still unclear in this country, which makes it difficult to prepare appropriate iron management policies. In order to fill this knowledge gap, we employ a dynamic material flow analysis method to uncover the key features of iron metabolism in Pakistan for the period of 2005–2020. The result shows that a total of 2.057 Mt of iron ore was extracted during this study period. Pakistan heavily relied on importing iron resources to meet its demand, mainly from China (13.14 %), Japan (6.86 %), the United Arab Emirates (6.24 %), and the United Kingdom (6.27 %). Meanwhile, China (43.5 %) and the United Arab Emirates (19.82 %) are the top two buyers of Pakistan's iron-related products. In addition, our results indicate that iron recycling was insufficient in Pakistan, with a recycling rate of only 15 %. Finally, several policy recommendations are proposed by considering the Pakistan's reality in order to enhance the overall iron resource efficiency.

The phase and morphology evolution of Y-Zr-O complex oxide dispersion-strengthened (ODS) Mo powders during mechanical alloying and annealing

Nanostructural Y-Zr-O complex oxide dispersion-strengthened (ODS) Mo alloys are designed for accident-tolerant fuel cladding. The phase and morphology evolution of ODS Mo powders during mechanical alloying (MA) and annealing were studied. The dissolution and reprecipitation mechanisms were revealed by quantitative calculation of dissolved Y and Zr amounts, thermodynamics and dynamics analysis, and phase analysis. The results reveal MA induces Mo grain refinement and a high density of dislocations in powders, facilitating the dissolution of Y2O3 and Mo2Zr and the formation of Mo supersaturated solid solution, rather than the negative mixing heat. By subtracting vacancies and oxygen effects, the dissolved amount is estimated as 2.2 at.% Y and 1.8 at.% Zr after 96 h-milling. During annealing, the Y-Zr-O complex oxide is precipitated in Mo-10 wt%Y2O3 powders above 900 °C since the introduced ZrO2 contamination during MA, and then cubic-Y2O3 beyond 1100 °C. The findings provide a scientific basis for controlling Y-Zr-O complex oxide nanoprecipitates and optimizing the service performance of Mo alloys.

Astragalin improves cognitive disorder in Alzheimer's disease: Based on network pharmacology and molecular docking simulation.

We investigate the mechanism of action of astragalin (AST) in the treatment of Alzheimer's disease (AD). Network pharmacology was conducted to analyze the relationships among AST, AD, and neuroinflammation, The APP/PS1 transgenic mice with AD were used in the experiments; to be specific, the influence of AST on the behavior of mice was analyzed by Morris water maze and eight-arm radial maze tests, the tissue inflammatory factor levels were detected by ELISA, and pathological changes were analyzed by H&E and immunohistochemical staining. Analysis results of network pharmacology suggested that AST exerted the multi-target effect on neuroinflammation in AD. Through molecular docking and dynamics analyses, COX2 might be the target of AST. Moreover, animal experimental results demonstrated that AST improved the behavior of AD mice, and enhanced the motor and memory abilities, meanwhile, it suppressed the expression of inflammatory factors in tissues and the activation of microglial cells. this study discovers that AST can suppress microglial cell activation via COX2 to improve neuroinflammation in AD.

SomaSeg: a robust neuron identification framework for two-photon imaging video

Objective.Accurate neuron identification is fundamental to the analysis of neuronal population dynamics and signal extraction in fluorescence videos. However, several factors such as severe imaging noise, out-of-focus neuropil contamination, and adjacent neuron overlap would impair the performance of neuron identification algorithms and lead to errors in neuron shape and calcium activity extraction, or ultimately compromise the reliability of analysis conclusions.Approach.To address these challenges, we developed a novel cascade framework named SomaSeg. This framework integrates Duffing denoising and neuropil contamination defogging for video enhancement, and an overlapping instance segmentation network for stacked neurons differentiating.Main results.Compared with the state-of-the-art neuron identification methods, both simulation and actual experimental results demonstrate that SomaSeg framework is robust to noise, insensitive to out-of-focus contamination and effective in dealing with overlapping neurons in actual complex imaging scenarios.Significance.The SomaSeg framework provides a widely applicable solution for two-photon video processing, which enhances the reliability of neuron identification and exhibits value in distinguishing visually confusing neurons.

Optimization design and simulation of chip-level micro-gas columnar preconcentrator structure based on ANSYS

Abstract To achieve the efficient preconcentration of measured sample gas in microfluidic chips, this paper proposes a design and simulation scheme for the chip-level micro-gas columnar pre-concentrated structure based on ANSYS software. Firstly, four kinds of chip-level micro-gas columnar preconcentrators with circular, semi-circular, triangular, and rhombic shapes were designed, and the simulation analysis of gas-phase micro-fluidic dynamics was performed on the chip-level micro-gas columnar preconcentrator by ANSYS software. The influence of different design parameters on the pre-concentrated effect of level chips micro-gas columnar preconcentrator was discussed. The simulation results show that the arrangement is a triangle arranged in reverse parallel, and the preconcentration effect of the chip-level micro gas column preconcentrator is better.