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Reasonable size accuracy of the mechanical part may be a key for the design of the complex transmission mechanism; thus, it is very important to evaluate the size errors of each part. Taking the conjugate cam-spatial rank feeding transmission mechanism as an example, the functions, such as the near-dwelling, fast-forwarding, working feeding, slow-forwarding, far-dwelling, fast-returning, quick-feeding-back, and slow-returning, are realized with the appropriate conjugate cam governing equations. The analytical expressions of the conjugate cams and functions of the angular motion and angular velocity between the conjugate cam and crank are derived. Considering the real machining errors of part, a concept of parameter sensitivity is proposed, and the magnitude and direction of the influence of typical parameter errors on the mechanism motion transfer characteristics are evaluated by this concept. This method provides a reliable reference for the precision design of mechanical structure parameters.

In engineering applications, cylindrical bars of 20 carbon steel are often subjected to a combination of tensile loading and torsional loading during the service, thereby causing premature failure or an accident. In order to explore the influence of loading sequence of tension and torsion on the mechanical properties of 20 carbon steel, tests of combined tension-torsion loading and combined torsion-tension loading are employed in this work. During experiments, a microscope is used for the in situ characterization of micro-damage evolution on the surface of specimens. At the same time, to analyze the influence of loading sequence on the stress distribution, ABAQUS software is utilized to conduct the relevant finite element simulation, where the results of finite element analysis are consistent with the experiments. Evidently, the torsional strength of 20 carbon steel is decreased with an increase in the pre-tensile stress, under the combined tension-torsion. However, the tensile strength of 20 carbon steel is enhanced with the increasing pre-torsional angles, under the combined torsion-tension. Moreover, the in situ images characterized the micro-damage evolution of 20 carbon steel under pure tension, pure torsion, combined tension-torsion and combined torsion-tension. It is concluded that the deference in loading sequence changes the failure mechanism of 20 carbon steel is different.

In this research, a protective concrete-filled steel plate composite wall (PSC) is developed, consisting of a core concrete-filled bilateral steel plate composite shear wall and two lateral replaceable surface steel plates with energy-absorbing layers. The PSC wall is characterised by high in-plane seismic performance as well as out-of-plane impact performance. Therefore, it could be employed primarily in high-rise constructions, civil defence initiatives, and buildings with stringent structural safety criteria. To investigate the out-of-plane low-velocity impact behaviour of the PSC wall, fine finite element models are validated and developed. Then, the influence of geometrical and dynamic loading parameters on its impact behaviour is investigated. The results show that the replaceable energy-absorbing layer could significantly decrease the out-of-plane displacement and plastic displacement of the PSC wall due to its large plastic deformation, which could absorb a significantly large amount of impact energy. Meanwhile, the PSC wall could maintain high in-plane seismic performance when subjected to impact load. The plastic yield-line theoretical model is proposed and utilised to predict the out-of-plane displacement of the PSC wall, and the calculated results agree very well with the simulated results.

Perovskite materials have driven tremendous advances in constructing electronic devices owing to their low cost, facile synthesis, outstanding electric and optoelectronic properties, flexible dimensionality engineering, and so on. Particularly, emerging nonvolatile memory devices (eNVMs) based on perovskites give birth to numerous traditional paradigm terminators in the fields of storage and computation. Despite significant exploration efforts being devoted to perovskite-based high-density storage and neuromorphic electronic devices, research studies on materials' dimensionality that has dominant effects on perovskite electronics' performances are paid little attention; therefore, a review from the point of view of structural morphologies of perovskites is essential for constructing perovskite-based devices. Here, recent advances of perovskite-based eNVMs (memristors and field-effect-transistors) are reviewed in terms of the dimensionality of perovskite materials and their potentialities in storage or neuromorphic computing. The corresponding material preparation methods, device structures, working mechanisms, and unique features are showcased and evaluated in detail. Furthermore, a broad spectrum of advanced technologies (

A family of structure-dependent methods is proposed based on discrete control theory. Although the displacement and velocity expression of this family method are similar to those of the previously published method developed by Mohammad Rezaiee-Pajand, the structure-dependent parameters of this family are different from the previously published method. The family of structure-dependent methods is named the MUSE algorithm method. Based on discrete control theory, a new family of integration algorithms is proposed by using the poles of the Newmark-[Formula: see text] method. Theoretical analysis indicated that the MUSE algorithm method possesses properties of zero amplitude decay and is self-starting. Also, its Period Elongation can be reduced by parameter ‘[Formula: see text]’. Numerical examples show that parameter ‘[Formula: see text]’ introduced in this paper can improve control Period Elongation and improve the accuracy of this method.

The application of micro-/nano-capsules in construction industries has been rising over the past decade. Polyurea with tunable chemical and morphological structure are of interesting polymers to prepare micro-/nano-capsules used in construction. The structure of polyurea micro-/nano-capsule is capable to be tailored via bulk emulsion or microfluidic method. Important factors for production of micro/nano-capsules are the rate of fabrication and having control over mean size, dispersity, and wall thickness. The bulk emulsion method provides higher yield of production with less control over sizes and dispersity in comparison to microfluidic technique. The main applications of polyurea micro-/nano-capsules in construction industries are categorized as thermal energy saving, self-healing concrete, self-healing polymers, and fire retarding. Polyurea showed appropriate thermal conductivity and mechanical properties which is required for encapsulation of phase change materials. Titanium dioxide polyurea microcapsules possess energy storage efficiency of 77.3% and thermal storage capacity of 99.9%. Polyurea microcapsules with sodium silicate cargo provided self-healing abilities for oil well cement in high temperature and showed higher self-healing abilities compared to gelatin microcapsules. Graphene oxide polyurea micro-/nano-capsules demonstrated 62.5% anti-corrosive self-healing efficiency in epoxy coating, and steel coated via dendritic polyurea microcapsules embedded polyurethane remained unchanged after long time immersion in salt water.

Treatment of the first natural frequency of a rotating nanocomposite beam reinforced with graphene platelet is discussed here. In regard of the Timoshenko beam theory hypothesis, the motion equations are acquired. The effective elasticity modulus of the rotating nanocomposite beam is specified resorting to the Halpin–Tsai micro mechanical model. The Ritz technique is utilized for the sake of discretization of the nonlinear equations of motion. The first natural frequency of the rotating nanocomposite beam prior to the buckling instability and the associated post-critical natural frequency is computed by means of a powerful iteration scheme in reliance on the Newton–Raphson method alongside the iteration strategy. The impact of adding the graphene platelet to a rotating isotropic beam in thermal ambient is discussed in detail. The impression of support conditions, and the weight fraction and the dispersion type of the graphene platelet on the acquired outcomes are studied. It is elucidated that when a beam has not undergone a temperature increment, by reinforcing the beam with graphene platelet, the natural frequency is enhanced. However, when the beam is in a thermal environment, at low-to-medium range of rotational velocity, adding the graphene platelet diminishes the first natural frequency of a rotating O-GPL nanocomposite beam. Depending on the temperature, the post-critical natural frequency of a rotating X-GPL nanocomposite beam may be enhanced or reduced by the growth of the graphene platelet weight fraction.

Structural behavior of RC structures under explosive loads is an emerging field of research especially RC columns since the damage of RC columns can lead to progressive collapse. Most research works investigated and concentrated on the behavior of RC columns when exposed to far-field detonations (FFD). A limited study is available on the effects of near-field detonation (NFD) and close-in detonation (CID) on the behavior of RC columns. Hence, the main purpose of the current research is to investigate the influence of different types of detonation scenarios on the dynamic behavior of RC columns. The influences of extreme loading conditions on the columns are defined by using Lagrangian analyses in LS-DYNA. Validation of the numerical model is implemented by comparing the numerical analysis results with UFC 3–340-02 Standard. It is shown that the model yields a reliable prediction of damage on all RC columns. Intensive studies are performed to evaluate the influences of various scaled distances on the dynamic behavior of the columns. The results demonstrated that when the columns are subjected to CID explosions, they undergo the maximum pressure and the columns fail due to severe impulsive regime loading. The results revealed that when the scaled distance is in the CID range, the peak blast load increases but the duration of the positive phase of the blast wave decreases resulting in higher amplitude, lower-duration shock pulse and when the scaled distance is in the FFD range, the peak blast load decreases but the duration of the positive phase blast wave increases resulting in lower amplitude, longer-duration shock pulse. Also, the results show that increasing the scaled distance in RC columns subjected to NFD and FFD detonations resulted in a further decrease in the peak deflection histories and damage degree of RC columns in comparison to CID explosions. The current investigation and the outcomes can be utilized for evaluation of the effect of an explosion on the RC columns.

This paper presents a predictive model of subsurface damage depth hSSD and surface roughness in semi-consolidated abrasive grinding based on indentation fracture theory to rapidly and non-destructively detect subsurface damage of the workpiece. To verify the accuracy of the proposed model, cross-sectional microscopy was used to detect subsurface damage along the (100) and (010) crystal lographic planes in grinding of gallium oxide. In addition, the effects of grinding method, abrasive particle size, grinding pressure, and grinding disc speed on the damage along the (100) and (010) planes were analyzed. The results show a nonlinear relationship between the depth of the gallium oxide subsurface damage and surface roughness generated by semi-consolidated abrasive grinding. Under the same grinding conditions, the damage layer depth in semi-consolidated abrasive grinding is lower than in free abrasive grinding. When the same grinding method is used, the subsurface damage depth is greater along the (100) plane than along the (010) plane under the same grinding conditions. When the abrasive particle size is decreased from W14 to W3, the depth of the subsurface damage layer is reduced by 30% in semi-consolidated abrasive grinding. Reducing the grinding pressure can reduce the amount of subsurface damage, and the speed of the grinding disc also affects the subsurface damage of gallium oxide. The subsurface damage depth has little effect. After optimizing the grinding parameters, the surface roughness of gallium oxide along the (100) and (010) planes was 23 nm and 12 nm, respectively, and hSSD was 2.9 μm and 2.1 μm, respectively. The proposed model of the relationship between subsurface damage depth and surface roughness can be used to achieve rapid, accurate, and non-destructive detection of the depth of subsurface damage and provides technical guidance for subsequent grinding and polishing processes.

Ice thermal storage (ITS) performance for cooling systems is greatly influenced by the poor thermal conductivity of phase change material (PCM). The effect of natural convection on the melting process is significant for heat transfer enhancement. Thus, the melting performance of PCM in a shell-and-tube latent heat storage (STLHS) unit is numerically studied by considering natural convection in terms of various heat source positions and configurations, i.e., central position, eccentric position, and flat-tube type. Temperature distribution, melting time, and the overall heat transfer coefficient during the process are investigated. The results show that the circulation vortex formed by natural convection is a dominant factor that affects melting front evolution and the overall heat transfer coefficient. When input heat flux is relatively weak, PCM below the heat source is liquefied first. In contrast, PCM in the upper part melts earlier when the heat flux is excellent. The overall heat transfer coefficient decreases sharply with the increase in melting time in the early stage. Then, the heat transfer coefficient tends to be constant. PCM in an STLHS unit with a heat source in a lower position and a configuration of vertical flat-tube type has a desirable performance when compared with other cases, which could provide good support for ITS application.

A functionally tunable and absorption-tunable terahertz (THz) metamaterial absorber based on vanadium dioxide (VO2) and graphene is proposed and verified numerically. Based on phase transition properties of VO2 and tunability of graphene, the switching performance between ultra-broadband and narrow-band near-perfect absorption can be achieved. We simulate and analyze the characteristics of the constructed model by finite element analysis. Theoretical calculations show that when VO2 is in the metallic state and the graphene Fermi energy is 0 eV, the designed absorber can perform ultra-broadband absorption. The absorber achieves greater than 95% absorption in the 2.85 - 10THz range. When VO2 is in the insulating state and the graphene Fermi energy is 0.7 eV, more than 99.5% absorption can be achieved at 2.3 THz. The absorption rate can be tuned by changing the conductivity of VO2 and the Fermi energy of graphene. Moreover, the proposed absorber displays good polarization insensitivity and wide incident angle stability. The design may have potential applications in terahertz imaging, sensing, electromagnetic shielding and so on.

This study aims to investigate the performance of a new damage detection method proposed based on the combination of two signal processing techniques which are complete ensemble empirical mode decomposition with adaptive noise and multiple signal classification (CEEMDAN-MUSIC). The proposed damage detection approach begins with determining the power density spectrum, namely, the pseudospectrum, from the acceleration response of a structure. Then, the CEEMDAN algorithm is used to decompose the vibration signal into a set of intrinsic mode functions (IMFs). Furthermore, the MUSIC algorithm is applied to the first IMF of the processed signal to determine the frequency pseudospectrum, prior to and post the damage states of the structure. The effectiveness of the proposed methodology is experimentally validated using a laboratory-scale model of a steel truss bridge exposed to a white noise excitation. The damage states of the truss bridge are implemented by replacing a specified diagonal element with reduced cross-sectional stiffness. The experimental results demonstrate the superiority of the CEEMDAN-MUSIC method in comparison with the performance of pure MUSIC and traditional frequency domain techniques. The advantages of the proposed technique are also discussed in terms of identifying the presence of the damage, addressing its location, and quantifying the damage levels which are summarized as the damage detection and characterization.

Developing efficient sensing materials with superior sensing capabilities of sensitive, fast, selective detection of volatile organic compounds (VOCs) is necessary for fields like environmental gas monitoring and non-invasive disease diagnosis. Recently, carbon nanotubes, graphene, MXene, and other carbon-based nanomaterials have been paid much attention for possible use as high-performance VOCs sensing materials due to unique physical structures and excellent electric properties. The tunability of the chemical character and surface properties of the carbon-based nanomaterials increases their potential in constructing selective sensors targeting VOCs gases. Besides, the mechanical flexibility of the carbon-based nanomaterials allows the new designs of gas sensing platforms and puts the carbon-based nanomaterials at the forefront of other sensing materials for wearable applications. In this review, we highlight the most recent progress of the carbon-based nanomaterials in the detection of VOCs gases with an emphasis on the available strategies for the construction of these VOCs gas sensors. These strategies are proved by addressing some representative paradigms, and their suitability in applications like environmental gas monitoring and non-invasive disease diagnosis is assessed. This review is intended to offer timely sources of information and provide insight for future research works on designing high-performance VOCs gas sensors by utilizing carbon-based materials.

Modern electronic devices are usually subjected to thermo-mechanical loads and prone to buckle during their operation. Thermo-mechanical stability is a crucial standard for their reliable applications. This paper explores the size effect on the thermo-mechanical behavior of the organic solar cells. An effective isogeometric analysis method combined with modified couple stress theory is presented. The thermo-mechanical buckling load-bearing capacities of the organic solar cells subjected to various in-plane loadings, temperatures, and geometrical parameters are discussed. Numerical results show that the size effect has significant effect on the thermo-mechanical load-bearing capacity. The stability region changes minimally when the material length scale parameter $$l$$ to cell thickness $$h$$ ratio is less than 0.2, while the stability region increases remarkably when it is larger than 0.2. Notably, if the material length scale parameter increases to its thickness, the stability region increased almost 25 times than that without size effect. Furthermore, the stability region is narrowest if the temperature is uniform across the thickness direction of the cell.