Kinematic synthesis of a robot with five degrees of freedom

Abstract

This paper studies the geometric design of a robot with five degrees of freedom. According to kinematic synthesis procedure, an industrial robot with five degrees of freedom was used as an example to illustrate the design concept. From the number synthesis point of view, the robot is one freedom less than adequate to perform a general three dimensional motion. The lack of full degree of freedom will restrict the available twist screws for the end‐effector. The unavailable twists of the robot were discovered based on the reciprocal screw system. Singular configurations of the robot were also examined. The dimensional synthesis of a robot is to decide the joint parameters to obtain a good workspace shape and volume. So far, there are no better rules which govern the relations between the joint parameters and the generation of workspace. Under this circumstance, the workspace geometric properties of a robot provide quantitative evaluation of the success of the dimensional synthesis. In this paper, workspace volume and other workspace properties such as the normalized volume index (NV1), volume centroid, and the higher volume moment of inertia are computed. The volume centroid gives the symmetric nature of the workspace, whereas the higher moment reveals the distribution and the compactness of the workspace valume.     

Cell-based quantification of homocysteine utilizing bioluminescent Escherichia coli auxotrophs

A cell-based quantitative assay system for Hcy has been developed by utilizing two Escherichia coli auxotrophs that grow in the presence of methionine (Met) and either homocysteine (Hcy) or Met, respectively. A bioluminescent reporter gene, which produces luminescence as cells grow, was inserted into the auxotrophs, so that cell growth can be readily determined. When the relative luminescence unit (RLU) values from the two auxotrophs immobilized within agarose gels arrayed on a well plate were measured, the amount of Hcy was quantitatively determined on the basis of differences between two RLU values corresponding to cell growth of two auxotrophs with excellent levels of precision and reproducibility. Finally, the diagnostic utility of this assay system was verified by its employment in reliably determining different stages of hyperhomocysteinemia in human plasma samples providing CVs of within and between assays that are less than 2.9% and 7.1%, respectively, and recovery rates of within and between assays that are in the range of 99.1-103.5% and 97.5-105.5%, respectively. In contrast to existing conventional methods, the new system developed in this effort is simple, rapid, and cost-effective. As a result, it has great potential to serve as a viable alternative for Hcy quantification in the diagnosis of hyperhomocysteinemia.     

Enhancement of localized surface plasmon resonance detection by incorporating metal-dielectric double-layered subwavelength gratings

In this study, we investigated the enhanced sensing performance of a localized surface plasmon resonance (LSPR) biosensor by employing metal-dielectric double-layered subwavelength grating structures. The numerical results showed that the LSPR substrate with a dielectric spacer can provide not only a better sensitivity but also a significantly improved reflectance characteristic. While the presence of metallic gratings leads to a broad and shallow reflectance curve inevitably, the dielectric spacer can prevent the propagating surface plasmons from being interfered by the locally enhanced fields excited at the gold gratings, finally resulting in a strong and deep absorption band at resonance. Therefore, the proposed structure could potentially open a new possibility of the enhanced LSPR detection for monitoring biomolecular interactions of low molecular weights.     

Partial oxidation of n-butane over ceria-promoted nickel/calcium hydroxyapatite

LPG has good infrastructure and is anticipated to be used for production of hydrogen, and n-butane which constitutes a main component of LPG for vehicles. Partial oxidation (POX) of n-butane is investigated in this research by employing ceria-promoted Ni/calcium hydroxyapatite catalysts (Ce _x Ni_2.5/Ca₁₀(OH)₂(PO₄)₆ x=0.1–0.3) which have recently been reported to exhibit good catalytic performance in POX of methane and propane. The experiments were carried out with changing ceria content, O₂/n-C₄H₁₀ ratio and reaction temperature. As the O₂/n-C₄H₁₀ ratio increased up to 2.75, the n-C₄H₁₀ conversion and H₂ yield increased and the selectivity of methane and other hydrocarbons decreased. But with O₂/n-C₄H₁₀=3.0, the n-C₄H₁₀ conversion and H₂ yield decreased. Ce_0.1Ni_2.5/Ca₁₀(OH)₂(PO₄)₆ showed the highest n-C₄H₁₀ conversion and H₂ yield on the whole. In durability tests, higher hydrogen yield and better catalyst stability were obtained with the O₂/n-C₄H₁₀ ratio of 2.75 than with the ratio of 2.5.     

Analysis of a robust and energy efficient transmission scheduling protocol in single‐hop ad hoc networks

A fully connected one‐hop ad hoc network constitutes a basic unit for managing self‐organizing networks such as IEEE 802.11 and 802.15.3 networks. Since energy efficiency is a critical issue in ad hoc networks, we develop an energy‐saving framework that includes scheduling for node‐to‐node direct communication. The scheduling is performed by a coordinator that is selected by some simple rule. We enhance IEEE 802.11 protocol by using our proposed framework, and analyze its energy efficiency in transmitting and receiving data. Through mathematical analysis, we confirm that our enhanced protocol significantly saves energy compared to the IEEE 802.11 protocol. We also investigate the robustness of our algorithm by covering the cases of uncooperative users, system malfunctioning, and channel errors. The numerical results confirm that our protocol works well under these hostile environments and maintains its advantage over the conventional scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

一种基于Proxy的Web应用安全漏洞检测方法及实现

指出了Web应用中存在的各种安全漏洞,在分析并总结Web应用安全漏洞特点的基础上,设计了一种基于Proxy的Web应用安全漏洞检测方法,该方法可以用来检测一些常见的Web应用安全漏洞,如参数篡改、跨站点脚本漏洞等.给出了利用该方法检测SQL代码插入、跨站点脚本算法的JAVA语言实现.     

Dielectric properties of the BaTiO3-AlN-additive system

The mixed system of BaTiO₃ and AlN has been investigated in terms of dielectric properties and microstructure. Two different types of additives, bismuth oxide and bismuth borosilicate glass, were used to lower sintering temperature. First, the addition of a fixed content (3 wt.%) of Bi₂O₃ provided densification at 1200^∘C where monotonous decreases of dielectric constant were found with increasing the content of AlN. On the other hand, the bismuth borosilicate glass was effectively used to decrease firing temperature to 850^∘C, which is suitable for thick film capacitor applications. A practical demonstration of thick film capacitors using a Ag electrode on a 96% alumina substrate indicated that the optimum composition of 76BaTiO₃-20AlN-4glass may be adequate for generating k of 79.4 and tan δ of 0.014 at 1 MHz as a result of the low temperature firing of 850^∘C in air atmosphere.     

Simulation of Ion Conduction in the ompF Porin Channel Using BioMOCA

In this paper, we present a full three-dimensional simulation of the ompF porin channel using BioMOCA, a self-consistent particle-based ion channel simulation tool, based on the Boltzmann Transport Monte Carlo methodology widely used to simulate conduction in the solid-state device. Significant computational speed-up over atomistic Molecular Dynamics simulations is achieved by treating protein, membrane and water as continuum dielectric background media and computing only the trajectories of mobile ions in solution. A realistic channel structure with permanent fixed charges is mapped onto a finite mesh using the Cloud-in-Cell scheme. Electrostatic forces, computed by solving Poisson equation at regular intervals, are added to a pair-wise ion-ion interaction, which is necessary to prevent the unphysical coalescence of finite-sized ions. The interaction between ions and water is modeled as a random scattering process that thermalizes the ion. Using this tool we computed the complete current-voltage characteristic of the porin channel in approximately one week using ten IBM p690 processors. We also present steady-state ion channel occupancies and compare them with results obtained from recent drift-diffusion based simulations.     

Bioinspired and biocompatible adhesive coatings using poly(acrylic acid)‐grafted dopamine

Poly(acrylic acid) (PAA) was grafted with dopamine to increase its adhesion force to metal surface. Nitinol plate surfaces were then modified by coating with PAA‐g‐dopamine. To synthesize PAA‐g‐dopamine, PAA was first activated by dicyclohexylcarbodiimide and N‐hydroxysuccinimide (NHS) to form PAA–NHS. Dopamine was then copolymerized with PAA–NHS in an aqueous medium at pH 8.5. We propose to increase the adhesion of adhesive PAA‐g‐dopamine on nitinol to improve its durability. In this article, we studied wettability, surface elemental composition, and surface morphology. Biocompatibility was also assessed by L929 fibroblast cells in vitro. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

水魔方转起来

水是生命之源,如何净化它并挖掘更多健康的饮水方式,一直让设计师们兴致勃勃。水对我们的生命起着重要的作用,它是生命的源泉,是人类赖以生存和发展不可缺少的最重要的物质资源之一。据联合国统计,全球淡水消耗量自20世纪初以来增加了约6～7倍,比人口增长速度高2倍。全球目前有14亿人缺乏安全清洁的食用水,即平均每5人中便有1人缺水。估计到2025年,全世界将有30亿人缺水。净化生命之源,一直让设计师们兴致勃勃。他们研发的各式净水设备,就如同神奇的魔方,转一转,便可带来一片纯净!