Generalized pseudo inverse kinematics at singularities for developing five-axes CNC machine tool postprocessor

This paper presents an analytical scheme for analyzing the singular configuration problem of general five-axes CNC machine tool. A computational technique based on the generalized pseudo inverse kinematics for finding out feasible solution of the problem is proposed. The technique is then used for developing post processor algorithm of five-axes CNC machine tool. Typical examples of singularity analysis are carried out, and real cutting parts are implemented for verifying the research result

Preconcentration of Arsenic Species in Environmental Waters by Solid Phase Extraction Using Metal-loaded Chelating Resins

Joint Research on Environmental Science and Technology for the Earth『Annual Report of FY 2002, The Core University Program between Japan Society for the Promotion of Science (JSPS) and National Centre for Natural Science and Technology (NCST)』pp.20-23, Core University Program Office, Fujita Laboratory, Dept. of Environmental Engineering, Osaka University, 200

Kinematic and dynamic modelling for a class of hybrid robots composed of m local closed-loop linkages appended to an n-link serial manipulator

Recently, more and more hybrid robots have been designed to meet the increasing demand for a wide spectrum of applications. However, development of a general and systematic method for kinematic design and dynamic analysis for hybrid robots is rare. Most publications deal with the kinematic and dynamic issues for individual hybrid robots rather than any generalization. Hence, in this paper, we present a novel method for kinematic and dynamic modelling for a class of hybrid robots. First, a generic scheme for the kinematic design of a general hybrid robot mechanism is proposed. In this manner, the kinematic equation and the constraint equations for the robot class are derived in a generalized case. Second, in order to simplify the dynamic modelling and analysis of the complex hybrid robots, a Lemma about the analytical relationship among the generalized velocities of a hybrid robot system is proven in a generalized case as well. Last, examples of the kinematic and dynamic modelling of a newly designed hybrid robot are presented to demonstrate and validate the proposed method

Dynamic analysis of two-link flexible manipulator considering the link length ratio and the payload

Dynamic modeling and analysis of flexible manipulators play an essential role in optimizing mechanical design parameters and control law of real robot systems. In this paper, a nonlinear dynamic model of a manipulator is formulated based on the Finite Element Method. To analyze the dynamic behavior effectively, a numerical simulation scheme is proposed by taking full advantages of MATLAB and SIMULINK toolboxes. In this manner, the effect of varying payload and link length ratio of the manipulator to its elastic displacement is dynamically taken into account. The simulation results show that the payload and length link ratio have significant influences on the elastic displacements of the system. In particular, a proper spectrum of the link length ratio, in which the flexural displacement of the end point of the manipulator is smallest, is demonstrated. To this end, the proposed methodology could be used further to select optimal geometric parameters for the links of new robot designs

Review: Possible removal of heavy metal and selective rare-earth ions by polymeric and nano-composite materials.

Heavy metal contamination in aqueous environment from natural processes and human’s activities including pesticides usage, mining, factories discharging and leaking irritation shows an extreme threat to environment and human health. The control of rising amount of heavy metal in environment not only requires critical observations at their original sources but also demands efficient removal methods. However, each conventional method is only suitable in a certain range of use. For example, inexpensive materials and convenient techniques are necessary for large scale heavy meal treatment, while high performance system to remove almost trace amount of heavy metals are critically required for drinking water treatment. On the other hands, heavy metal treatments must be applicable in some crucial environment conditions. Among solutions for environmental heavy metal control, polymeric materials have showed many advantages to enhance the performance of conventional heavy metal adsorbents. Possessing functional chemical moieties on their side chains and backbones, polymers can act as main metal ion adsorption component and/or effective supports for the adsorption property. In addition, the utilization of polymeric components can result in a low corrosion, selectivity, controllability, and recyclability of absorbents when operated in real environment conditions. This article summarizes the preparation techniques and desirable properties of polymer for removal of toxic heavy metal ion as well as the possibility of polymers in collecting some rare noble metal ions. Keywords. Heavy metal ions, nano-composite, polymer

A novel mathematical approach for finite element formulation of flexible robot dynamics

In conventional Finite Element – Lagrangian methods, the dynamics model of a flexible robot is usually formulated based on a critical assumption that the kinetic energy of an element is approximately calculated with an integral of mass point energy. Since the energy integral is implicit, the formulation of the dynamics model is also very complex and implicit. Hence, this paper develops a new mathematical approach for the dynamic modelling of a general flexible/rigid robot. The proposed method is more comprehensive and efficient in comparison with the previous ones because it no longer requires the calculation of the symbolic integrals and the implicit expressions of the elemental and global mass matrices. Besides, the proposed approach is applicable for both the flexible robots and the hybrid flexible/rigid robots. To validate the proposed method, numerical simulations and experimental results are presented

Prevalence and Determinants of Medication Adherence among Patients with HIV/AIDS in Southern Vietnam

This study was conducted to determine the prevalence and determinants of medication adherence among patients with HIV/AIDS in southern Vietnam. METHODS: A cross-sectional study was conducted in a hospital in southern Vietnam from June to December 2019 on patients who began antiretroviral therapy (ART) for at least 6 months. Using a designed questionnaire, patients were considered adherent if they took correct medicines with right doses, on time and properly with food and beverage and had follow-up visits as scheduled. Multivariable logistic regression was used to identify determinants of adherence. KEY FINDINGS: A total of 350 patients (from 861 medical records) were eligible for the study. The majority of patients were male (62.9%), and the dominant age group (≥35 years old) accounted for 53.7% of patients. Sexual intercourse was the primary route of transmission of HIV (95.1%). The proportions of participants who took the correct medicine and at a proper dose were 98.3% and 86.3%, respectively. In total, 94.9% of participants took medicine appropriately in combination with food and beverage, and 75.7% of participants were strictly adherent to ART. The factors marital status (odds ratio (OR) = 2.54; 95%CI = 1.51-4.28), being away from home (OR = 1.7; 95%CI = 1.03-2.78), substance abuse (OR = 2.7; 95%CI = 1.44-5.05), general knowledge about ART (OR = 2.75; 95%CI = 1.67-4.53), stopping medication after improvement (OR = 4.16; 95%CI = 2.29-7.56) and self-assessment of therapy adherence (OR = 9.83; 95%CI = 5.44-17.77) were significantly associated with patients' adherence. CONCLUSIONS: Three-quarters of patients were adherent to ART. Researchers should consider these determinants of adherence in developing interventions in further studies

Real time inverse kinematics of a general 5-axis CNC machine

In most of the previous investigations, the kinematics model of five-axis computer-numerical control (CNC) centers was formulated just at the position level, and the differential kinematic relationships (velocity, acceleration and jerk of the five joints of a five-axis center) that are necessary for several purposes, especially for investigating the relationship between the limits of a machine’s drives and the feed rate maximization (the productivity maximization), have been overlooked. Therefore, this paper addresses the differential kinematic modelling and analysis for the five-axis CNC centers. In particular, the differential kinematic equations are formulated in a parametric domain so that they are useful for investigating the kinematic behaviors of the five-axis centers in real time

In-Channel-Grown Polypyrrole Nanowire for the Detection of DNA Hybridization in an Electrochemical Microfluidic Biosensor

A triple electrode setup with a Pt pseudo-reference electrode integrated in a polydimethylsiloxane- (PDMS-) based microchamber was designed and fabricated. The integrated electrodes were deposited onto SiO2/Si substrate by sputtering. The PDMS microchamber was patterned using an SU-8 mold and sealed with electrodes in oxygen plasma. Polypyrrole nanowires (PPy NWs) were electrochemically grown in situ at an accurate position of the working electrode in the sealed microchamber instead of in an open system. The DNA probe sequences were simply introduced into the channel to form bonds with the nanowires. A detection limit of 20 pM was achieved using a lock-in amplifier. The electrochemical characteristics produced by the hybridization of DNA strands in the microchamber showed a good signal/noise ratio and high sensitivity. Measurement of the DNA sensor in narrow space also required much less volume of the analytical sample compared with that in an open measuring cell. Results showed that this simple system can potentially fabricate nanostructures and detect bio/chemical molecules in a sealed system