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Time-dependent reliability-oriented sensitivity analysis (ROSA) is a potent technique utilized to assess the impact of uncertain random input variables on the time-dependent reliability of planar linkage mechanisms. However, in cases where these random variables exhibit significant correlation behavior, the existing time-dependent ROSA indices will mislead the decision-makers in distinguishing between distinct types of uncertainty effects. To tackle this problem, this study commences by examining the connotations of main and total effect indices for correlated variables. Three new time-dependent ROSA indices are proposed in this work, specifically, the individual uncorrelated effect index, the total correlated effect index, and the individual interaction effect index, which enable a comprehensive exploration of the diverse effects of correlated random variables on the time-dependent reliability of planar linkage mechanisms. Additionally, efficient computational procedure is developed by combining the envelope function method with Monte Carlo simulation to estimate the proposed time-dependent ROSA indices. Finally, the proposed approach is applied to a four-bar mechanism and a rack-and-pinion steering linkage for illustrating the necessity and superiority of exploring the correlation effects in identifying failure sources with ROSA approaches.

Gaseous therapy based on nitric oxide (NO), as a potential anti-tumor treatment strategy, has attracted great attention, but the targeted and controlled gas release in the tumor site still remains a challenge. In addressing these difficulties, a near-infrared (NIR) light-triggered NO release nanogenerator with a “linkage mechanism” was designed on the basis of sodium nitroprusside-doped mesoporous Prussian blue nanoparticles, in which the outer structure was modified with pH-sensitive gatekeeper chitosan and tumor-targeting agent folic acid. The “linkage mechanism” can achieve precise release of NO under the control of photothermal effect at tumor site, which can couple photothermal therapy and gas therapy to address the premature release of gas during transportation. Meanwhile, the amount of released gas can be controlled by adjusting the irradiation time and laser intensity. Furthermore, as-fabricated nanocomposites hold high photothermal conversion efficiency under NIR laser irradiation, resulting in the on-demand release of NO and chemotherapy drugs. The released NO can inhibit the expression of hypoxia-inducible factor α (HIF-1α) and alleviate the hypoxic tumor microenvironment, thereby enhancing the efficacy of chemotherapy. Moreover, in vitro and in vivo experiments exhibited remarkable antitumor efficiency, and the synergistic gas/chemo/photothermal therapy of deep tumors was achieved. These findings indicate an effective strategy to stimulate further the development of deep tumor therapy, which may provide new insights into other NO-related medical applications.

A novel optimization-based approach for automated synthesis of linkage mechanisms is introduced. The method involves using moving morphable links (MMLs) as design components in topology optimization. These links float in the design space, connecting to create a linkage mechanism with a target output path for a given input motion. The design change of each link is represented by four design variables, corresponding to the positions of its endpoints. This results in a significant decrease in the number of design variables when compared to a model employing spring-connected rigid blocks (SBM), which is one of the most effective design models for topology optimization of linkage mechanisms. Additionally, the use of MML allows for the synthesis of mechanism layouts with cross-links, which cannot be achieved using the SBM. The proposed approach’s efficiency is further enhanced due to the use of global optimizers to solve the optimization problem. For this investigation, the Bayesian optimization method is employed. To improve the effectiveness of the global optimizer by finding optimal hyperparameter settings, the study of the design space’s nonlinearity is conducted. The proposed method’s validity is demonstrated by successfully solving synthesis problems involving four-bar mechanisms and six-bar mechanisms including cross-link layouts.

The flexibility of thermoelectric generators (TEGs) is important for low-contact thermal resistance to curved heat sources. However, approaches that depend on soft materials, which are used in most existing studies, have the problem of low performance in terms of the substrate’s thermal conductivity and the thermoelectric conversion efficiency of the thermoelectric (TE) elements. In this study, we propose a method to fabricate “Origami-TEG”, a TEG with an origami structure that enables both flexibility and the usage of high-performance rigid materials by self-folding. By applying the principle of the linkage mechanism to self-folding, we realized a fabrication process in which the TE element-mounting process and the active-material-addition process were separated in time. The fabricated origami-TEG showed similar internal resistance and maximum output power when attached to heat sources with flat and curved surfaces. Furthermore, it exhibited high-performance stability against both stretching and bending deformations.

An optimization design method is presented to reduce the undesirable vibrations caused by clearance for planar linkage mechanism. A clearance joint is defined and considered a contact/impact force constraint. Contact and impact force models for the clearance joint are established using a normal contact force model based on Hertz model with energy loss and a tangential friction model based on modified Coulomb model with dynamic friction coefficient, respectively. In view of the clearance joint, dynamic equations and optimization method for a planar four-bar mechanism are then presented as an application example. The optimization aims to minimize the maximum absolute acceleration peaks of the mechanism by determining the link lengths of the planar linkage mechanism. Finally, the optimization design is solved by a generalized reduced gradient algorithm. Results show evident decrease in vibration peaks of the mechanism and obvious reduction in the contact forces in the clearance joint, which contribute to a good performance of planar linkage mechanism systems.

The synthesis of planar linkage mechanisms by a topology optimization method has recently received much attention because both their numbers and dimensions can be simultaneously determined without baseline layouts. To synthesize a mechanism to produce a desired path at its end-effector, a desired path can be defined with or without prescribed timing. While earlier topology optimizations of mechanisms were all concerned with paths with prescribed timing, no study to deal with the topology optimization of mechanisms for path generation without prescribed timing is carried out in spite of its importance. The aim of this study is to propose and set up a gradient-based topology optimization formulation to synthesize planar linkage mechanisms that generate desired paths without prescribed timing. To this end, the desired path of the end-effector is expressed by the centroid distance function which is then represented by its Fourier descriptors. Then a topology optimization formulation using the Fourier descriptors is developed and the sensitivity analysis based on the Fourier descriptors is derived. Several numerical case studies are considered to verify the effectiveness of the proposed formulation. Some numerical issues appearing with the use of the Fourier descriptors are also investigated.

Gears are foundational tools used to transmit or modify mechanical energy or motion. Implementing gears into planar linkage mechanisms is less common but can be a similarly valuable technique that takes advantage of the high efficiency of gears while producing complex and precise motions. While recent numerical methods for designing these geared planar linkage mechanisms (GPLMs) have proliferated in the literature, analytical approaches have their merits and have received less attention. Here, an analytical alternative is presented as a modification of the complex-number loop-based synthesis method for designing multiloop mechanisms. Some of the base topologies for geared dyad, triad, and quadriad chains are presented, along with a numerical example demonstrating the solution procedure’s effectiveness.

Defining the linkages between landscape change, disease ecology and human health is essential to explain and predict the emergence of Plasmodium knowlesi malaria, a zoonotic parasite residing in Southeast Asian macaques, and transmitted by species of Anopheles mosquitos. Changing patterns of land use throughout Southeast Asia, particularly deforestation, are suggested to be the primary drivers behind the recent spread of this zoonotic parasite in humans. Local ecological changes at the landscape scale appear to be increasing the risk of disease in humans by altering the dynamics of transmission between the parasite and its primary hosts. This paper will focus on the emergence of P. knowlesi in humans in Malaysian Borneo and the ecological linkage mechanisms suggested to be playing an important role.

We propose a gradient-based topology optimization method to synthesize a planar linkage mechanism consisting of links and revolute/prismatic joints, which converts an input motion to a desired output motion at its end effector. Earlier gradient-based topology optimization methods were mainly applicable to the synthesis of linkage mechanisms connected by revolute joints only. The proposed method simultaneously determines not only the topology of planar linkage mechanisms but also the required revolute and/or prismatic joint types. For the synthesis, the design domain is discretized into rectangular rigid blocks that are connected to each other by the newly proposed revolute and prismatic joint elements, the joint states of which vary depending on the corresponding design variables. The new concept of joint elements is materialized thorough an elaborately configured set of zero-length springs whose stiffnesses vary as the functions of the design variables. Therefore, any connectivity state among unconnected, rigidly connected, revolute joint, and prismatic joint states can be represented by properly adjusting the stiffnesses. After presenting our modeling, formulation, and sensitivity analysis, the developed method is tested with verification examples. Then the developed method is extended to be able include additional shape design variables and applied to solve a realistic problem of synthesizing a finger rehabilitation robotic device. We expect the developed method to play a critical role in synthesizing a wide class of general linkage mechanisms.

Insulators on power lines require regular maintenance by operators in high-altitude hazardous environments, and the emergence of aerial manipulators provides an efficient and safe support for this scenario. In this study, a lightweight telescopic aerial manipulator system is developed, which can realize the installation and retrieval of insulator inspection robots on power lines. The aerial manipulator has three degrees of freedom, including two telescopic scissor mechanisms and one pitch rotation mechanism. Multiple types of cameras and sensors are specifically configured in the structure, and the total mass of the structure is 2.2 kg. Next, the kinematic model, dynamic model, and instantaneous contact force model of the designed aerial manipulator are derived. Then, the hybrid position/force control strategy of the aerial manipulator and the visual detection and estimation algorithm are designed to complete the operation or complete the task. Finally, the lifting external load test, grasp and installation operation test, as well as outdoor flight operation test are carried out. The test results not only quantitatively evaluate the effectiveness of the structural design and control design of the system but also verify that the aerial manipulator can complete the accurate automatic grasp and installation operation of the 3.6 kg target device in outdoor flight.