Type Synthesis Method for the Translational Decoupled Parallel Mechanism Based on Screw Theory

Coupling is the significant characteristic of parallel mechanism,while it is just the coupling that brings about much difficulty for the configuration design,theoretical analysis and the development of the control system of the parallel mechanism. And recently,the research on the decoupled parallel mechanism becomes one of the research hot points in the mechanism fields. In this paper,a type synthesis method for the translational decoupled parallel mechanism( TDPM) is proposed based on the screw theory. To achieve the decoupling characteristics of the translational parallel mechanism,the translational decoupled criterion for type synthesis of the branches are presented in this paper. According to this criterion and the realization conditions of rotational degree of freedom of the mechanism proposed former,a large number of branches for the TDPM are obtained. Taking the three degrees of freedom( DOFs) TDPM as an example,the process of type synthesis is discussed in detail. Using this proposed type synthesis method,a serial of translational decoupled parallel mechanisms, including but not limited to all the existing typical 3-DOF TDPMs, are obtained, which identifies the correctness and effective of the method. The contents of this paper provide a reference and possess significant theoretical meanings for the synthesis and development of the novel decoupled parallel mechanisms.

Overview of Rubik's Cube and Reflections on Its Application in Mechanism

Rubik’s Cube is a widely popular mechanical puzzle that has attracted attention around the world because of its unique characteristics. As a classic brain-training toy well known to the public, Rubik’s Cube was used for scientific research and technology development by many scholars. This paper provides a basic understanding of the Rubik’s Cube and shows its mechanical art from the aspects of origin and development, characteristics, research status and especially its mechanical engineering design, as well as making a vision for the application in mechanism. First, the invention and origin of Rubik’s Cube are presented, and then the special characteristics of the cube itself are analyzed.After that, the present researches of Rubik’s Cube are reviewed in various disciplines at home and abroad, including the researches of Rubik’s Cube scientific metaphors, reduction algorithms, characteristic applications, and mechanism issues. Finally, the applications and prospects of Rubik’s Cube in the field of mechanism are discussed.

Clinical factors associated with the number of gallbladder polyps

Gallbladder polyps(GBPs),which are defined as a pathological change protruding from the gallbladder mucosa,are one of the main causes of hospital admission for cholecystectomy.The incidence of GBPs is 4.2 to 9.5%in China.To date,the etiology of GBPs has not yet been clearly defined.According to previous studies,metabolic status is strongly associated with GBPs.⑵A single polyp is more likely to exhibit a malignant transformation,and large(diameter greater than 10 mm)single polyps should be resected together with the entire gallbladder.However,multiple polyps seem unlikely to transform.Thus,number of GBPs is an important factor that affects the treatment of GBPs.However,clinical factors associated w让h the number of GBPs are not completely understood;therefore,the aim of the current study is to investigate these factors.