A global approach for using kinematic redundancy to minimize base reactions of manipulators

An important consideration in the use of manipulators in microgravity environments is the minimization of the base reactions, i.e. the magnitude of the force and the moment exerted by the manipulator on its base as it performs its tasks. One approach which was proposed and implemented is to use the redundant degree of freedom in a kinematically redundant manipulator to plan manipulator trajectories to minimize base reactions. A global approach was developed for minimizing the magnitude of the base reactions for kinematically redundant manipulators which integrates the Partitioned Jacobian method of redundancy resolution, a 4-3-4 joint-trajectory representation and the minimization of a cost function which is the time-integral of the magnitude of the base reactions. The global approach was also compared with a local approach developed earlier for the case of point-to-point motion of a three degree-of-freedom planar manipulator with one redundant degree-of-freedom. The results show that the global approach is more effective in reducing and smoothing the base force while the local approach is superior in reducing the base moment

A Theoretical Study on the use of Passive Soil Resistance in Winch Anchor Design

This paper describes work being carried out to determine the length and depth of a cutting blade required to support a rescue vehicle fitted with a winch. Analytical work described relates mostly to the suitability of blade used. The design was confined to the case of the wide cutting blade moving in a direction perpendicular to the breadth of the blade because of its two dimensional simplicity. The approach adopted was based on a method already presented for the rapid calculation of passive soil resistance on a plane wide structure extending to the soil surface and having any rake angle as well as a wide range of directions of interface motion

The Development of Photosystem II-Herbicide Detection Method Using Microalgae as a Biosensor

Herbicides have been found to be significant pollutants of water bodies. In order to control and monitor the pollution, a convenient, sensitive and reliable method is needed. The main objective of this study is to develop a new method to measure the fluorescence yield of microalgae in order to detect photosystem II (PSII) specific herbicides in polluted water. The system was based on a simple mixing of microalgae with PSII specific herbicides. The measured signal was in the form of fluorescence intensity. The study involved the screening of test organisms, determining the best condition of the culture and obtaining a standard curve for each of the PSII herbicides. Only three herbicides were studied; atrazine, simazine and diuron. Chlorella vulgaris was found as the most suitable test organism compared with Chlorococcum sp., Scenedesmus quadriqauda and Selenastrum sp .. Nutrient replacement culturing method was selected as the best condition to grow C. vulgaris. A standard curve was determined for each of the herbicides. C. vulgaris was able to signal atrazine's concentration above 0.04µM according to the standard curve equation. Simazine can be signalled at above 0.05µM from its equation, while diuron can be signalled at above than O.09µM. However, -this basic study needs more infonnation and improvement to be done in the future, so that its full potential can be realised

A width of cut analysis on the performance of a rotary strip tiller

This paper describes a soil bin study on the effect of blade widths upon rotary tiller performance which forms part of the research undertaken by the author on rotary tillage. Blades used were designed and tested at several forward and rotor speed combinations using a single rotor flange. Results obtained for each combination of forward and rotor speed show significant increase in power consumption as cutting width increased. In terms of specific power, however, the wider the cutting widths the lower the specific power values. The highest degree of soil pulverization was caused by the smallest width at the smallest bite length

Base reaction optimization of redundant manipulators for space applications

One of the problems associated with redundant manipulators which were proposed for space applications is that the reactions transmitted to the base of the manipulator as a result of the motion of the manipulator will cause undesirable effects on the dynamic behavior of the supporting space structure. It is therefore necessary to minimize the magnitudes of the forces and moments transmitted to the base. It is shown that kinematic redundancy can be used to solve the dynamic problem of minimizing the magnitude of the base reactions. The methodology described is applied to a four degree-of-freedom spatial manipulator with one redundant degree-of-freedom

Behaviour of oil palm shell reinforced concrete beam partly replaced by palm oil fuel ash

In Malaysia, issue of natural contamination coming about because of transfer of Palm Oil Fuel Ash (POFA) which is a by-item from palm oil mill has started exploration to consolidate this waste in Oil Palm Shell (OPS) lightweight concrete structural. The current investigates the behaviour of oil palm shell reinforced concrete beam partly replaced by palm oil fuel ash. All mixes were casted in total of 4 reinforced concrete beam and 24 cubes with OPS RC mixes were producing by replaced 20% of POFA on cement, sand and aggregates were fabricated and tested. The flexural test and compressive test is conducted in accordance to BS EN 12390 – 3 and BS EN 12390 – 5 at the age of 7 and 28 days. The Data presented include the load – deflection curves, ductility, compressive strength and cracking pattern. From the result, it was observed that mixes with replaced POFA on cement would enhance the strength of concrete and from the flexural test shows that with replacement on cement, the ductility of beam is better than others replacement

Leadership qualities of university librarians in Malaysia / Kamariah Nor Mohd Desa

The purpose of this study is to explore the leadership qualities required for Malaysian public university librarians that enhances customer satisfaction. The objectives of the study are (1) to examine the perceptions of librarians on their leadership qualities, (2) to examine the perceptions of subordinates on the leadership qualities of their librarians, (3) to examine the perceptions of the heads of departments on the leadership qualities of librarians who are their subordinates, (4) to assess the satisfaction of customers on library services, (5) to examine the relationship between the various dimensions of leadership qualities, (6) to compare the perceptions of different groups of respondents on leadership qualities, (7) to compare the perceptions of users on the importance and performance of library services, and (8) to identify factors (e.g. transformational leadership, emotional intelligence and servant leadership) affecting leadership skills. The study covers 20 public university libraries in Malaysia. Respondents are librarians at all levels, head of departments, subordinates and library customers. The survey method is adopted. Data are collected through four (4) sets of questionnaires. The study adopts the 360 degree method in which the perceptions of respondents are gauged from multiple perspectives, thereby providing more data and information

Effects of cutting tool coating on surface roughness in machining pre-hardened steel (p20)

Quality of surface roughness is one of the challenges in the industry to produce high quality products. Cutting parameters and type of cutting tools are the factors that affect the quality of surface roughness. The purpose of this study is to examine the influences of different types of cutting tools coating and cutting parameters on the surface roughness. The cutting tools used are (TiN, TiCN and TiAlN). Taguchi method is used with three factors and three levels which is spindle speed (500. 1000, 1500) rpm, feed rate (500, 800, 1000) mm/min and diameter tool size (8, 10, 12) mm. The experimental results showed that, with larger diameter tool size the value of surface roughness will decrease. Same goes to spindle speed. When increasing spindle speed from (500-1500) rpm, the value of surface roughness also decreases. Different results surface roughness in feed rate, lower feed rate will produce better surface roughness. With suitable cutting parameters, TiAlN showed in decreasing surface roughness compare to the other two types of cutting tools. Confirmation test had verified that Taguchi design was successful in investigating the effect type of cutting tool coating on the surface roughness