Concurrent design of a three-link manipulator prototype

This paper presents an affordable and comprehensive robotic model of critical aid to any engineering school involved in teaching robotics. We present the stages of designing a three-link robot manipulator prototype that was built as part of a research project for establishing a prototyping environment for robot manipulators. Building this robot helped to determine the required subsystems and interfaces for building the prototyping environment, and provided hands-on experience for real problems and difficulties that are addressed and solved using this environment. The robot is now successfully used as an educational tool in robotics and control classes.     

Improving the Accuracy of Scheduling Analysis Applied to Distributed Systems Computing Minimal Response Times and Reducing Jitter

A well-established approachto the verification of end-to-end response times for distributed,hard real-time systems is an integrated scheduling analysis ofboth task processing and message communication. Hitherto, publishedanalyses have been confined to the computation of worst-casebounds only and best-case response times have been ignored, assumedto be zero or treated approximately. However, there are compellingreasons for computing both upper and lower bounds on responsetimes, not only to allow the verification of best-case performancebut also to improve the accuracy of the overall analysis. Thispaper describes a precise best-case execution time analysis whichreduces jitter and extends distributed scheduling analysis toyield more accurate upper and lower bounds on system responsetimes. The analysis is combined with existing results for worst-caseresponses in a single scheduling algorithm to compute both upperand lower bounds on end-to-end response in distributed systems.A design tool has been developed to automatethe analysis and support the performance verification of diversereal-time systems composed of tasks executing on multiple processorswhich communicate using the Controller Area Network (CAN) fieldbus.     

Photoinitiation systems and thermal decomposition of photodefinable sacrificial materials

The exposure characteristics of norbornene‐based photosensitive sacrificial materials as functions of the photoinitiator have been investigated. The results show that the initiator, bis(2,4,6‐trimethylbenzoyl)‐phenylphosphine oxide, provides high photosensitivity and an adjustable contrast factor. The kinetics of the thermal decomposition of the polymers have been investigated with dynamic and isothermal thermogravimetric analysis to determine the most appropriate conditions for the thermal decomposition of the sacrificial polymers. The reaction is slightly higher than first‐order, and a single mechanism can account for the decomposition throughout the process. The dependence of the kinetic parameters on the composition of the copolymers has been studied, and the reaction order remains unchanged; however, the activation energy is lower when the alkenyl‐substituted norbornene content is increased in the copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1186–1195, 2003     

The effects of extruder variables on the gelatinisation of corn starch

The first stage of a study of the extrusion of starch-based materials is described. The chemical and physical changes which occur in the extrusion of a corn starch-water system relative to fifteen extruder variables have been investigated. A mathematical model of the extruder has been obtained from analysis of the data. The important variables were found to be moisture, barrel and die temperatures, screw speed and screw geometry. A strong interaction between moisture and barrel temperature was found to occur. These variables in the model account for 90.5% of the variance in the data obtained. The effects of the variables on the gelatinisation and shearing mechanical degradation of starch are discussed.     

Evaluation of vetiver oil and seven insect-active essential oils against the Formosan subterranean termite

Repellency and toxicity of 8 essential oils (vetiver grass, cassia leaf, clove bud, cedarwood, Eucalyptus globules, Eucalyptus citrodora, lemongrass and geranium) were evaluated against the Formosan subterranean termite, Coptotermes formosanus Shiraki. Vetiver oil proved the most effective repellent because of its long-lasting activity. Clove bud was the most toxic, killing 100% of termites in 2 days at 50 g/cm². The tunneling response of termites to vetiver oil also was examined. Vetiver oil decreased termite tunneling activity at concentrations as low as 5 g/g sand. Tunneling and paper consumption were not observed when vetiver oil concentrations were higher than 25 g/g sand. Bioactivity of the 8 oils against termites and chemical volatility were inversely associated. Listed in decreasing order of volatility, the major constituents of the 8 oils were: eucalyptol, citronellal, citral, citronellol, cinnamaldehyde, eugenol, thujopsene, and both - and - vetivone. Vetiver oil is a promising novel termiticide with reduced environmental impact for use against subterranean termites.     

The perchlorate-assisted formation of lead dioxide on lead

Perchloric acid affects the phase formation process during the oxidation of lead to PbO₂ in dilute sulphuric acid. In sulphuric acid, the reaction involves a two-dimensional instantaneous nucleation process for the production of PbO₂. In the mixed acid, the growth of PbO₂ in low concentrations (20 mM) of added perchlorate ion remains two-dimensional but the nucleation becomes progressive and at higher perchlorate concentrations phase formation occurs by three-dimensional growth. A range of perchlorate concentration (30–40 mM) exists where the attack is on an advancing front (analogous to the electrodeposition of a metal from solution), in which the PbO₂ steadily advances into the metal. A mechanism is proposed for the Planté reaction process.     

Railroad bridge instrumentation with fiber-optic sensors

Fiber-optic sensors were installed on fatigue-critical components in the superstructure of a railroad bridge to monitor dynamic strains induced by trains crossing the bridge as well as to detect the onset of cracks. Each fiber Fabry-Perot interferometer (FFPI) strain gage was adhesively bonded to a stainless-steel strip to facilitate all-weather installation on the steel bridge members by spot welding. FFPI strain sensors were also installed on a rail at an approach to the bridge. Electrical resistive strain gages were colocated with the fiber-optic sensors on the bridge for the purpose of performance verification. In addition to the strain gages, fiber-optic continuity sensors for crack detection were bonded to the structure at critical locations. A telemetry system for transmitting the data over telephone lines was also installed at the bridge site. Dynamic response of the fiber-optic strain sensors is comparable with that of the electrical gages, and their performance has not degraded in the year since the initial installation.     

Mass balance of metolachlor in a grassed phytoremediation system

Metolachlor is a point-source pollutant at agrochemical dealerships in the Midwest, as well as a non point-source contaminant of surface waters caused by runoff. Prairie grasses have been used in filter strips to control runoff and are also useful for phytoremediation; however, little is known about the fate of metolachlor and its metabolites within a grassed system. Effects of uptake by prairie grasses on the formation and fate of degradation products are not known. In this study, [U-ring-14C]metolachlor was added to enclosed systems to determine the fate of the parent compound and its metabolites in soil and plants. Mineralization and volatilization were monitored over the 97 day study and found to be 1.05 and 0.2%, respectively, for vegetated systems. At the end of the study, soil and plant material was evaluated for the presence of parent metolachlor and selected metabolites, as well as bound residues. Metolachlor ethane sulfonic acid was the dominant metabolite in soil and plant tissue. Over 7% of applied radioactivity was taken up by the grasses, and plant uptake/metabolism appeared to be the main mechanism for phytoremediation of metolachlor. Vegetation significantly reduced the amount of metolachlor in soil by 9%, indicating potential success as a remediation tool.     

福州大学新校区环境规划

通过借鉴近现代世界风景园林学科理论，以中国山水园林手法为骨架，以现代校园文化活动为问题切入点进行一次现代校园环境规划尝试。福州大学校园环境设计围绕着山体保护改造利用、现状池塘、湿地、溪流等水系的整理、大片的自然林地恢复等方面反复推敲，形成了富有地方特色的山水校园环境，以中国自然山水意境来创建和谐校园：设计同时考虑到校园交通、教学及校园文化活动等的需求，形成了培育高尚人文气息的物质空间。