1,507 research outputs found
Multiple configuration shell-core structured robotic manipulator with interchangeable mechatronic joints : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Engineering in Mechatronics at Massey University, Turitea Campus, Palmerston North, New Zealand
With the increase of robotic technology utilised throughout industry, the need for skilled
labour in this area has increased also. As a result, education dealing with robotics has
grown at both the high-school and tertiary educational level. Despite the range of
pedagogical robots currently on the market, there seems to be a low variety of these
systems specifically related to the types of robotic manipulator arms popular for industrial
applications. Furthermore, a fixed-arm system is limited to only serve as an educational
supplement for that specific configuration and therefore cannot demonstrate more than
one of the numerous industrial-type robotic arms.
The Shell-Core structured robotic manipulator concept has been proposed to improve the
quality and variety of available pedagogical robotic arm systems on the market. This is
achieved by the reconfigurable nature of the concept, which incorporates shell and core
structural units to make the construction of at least 5 mainstream industrial arms
possible. The platform will be suitable, but not limited to use within the educational
robotics industry at high-school and higher educational levels and may appeal to
hobbyists.
Later dubbed SMILE (Smart Manipulator with Interchangeable Links and Effectors), the
system utilises core units to provide either rotational or linear actuation in a single plane.
A variety of shell units are then implemented as the body of the robotic arm, serving as
appropriate offsets to achieve the required configuration. A prototype consisting of a
limited number of ‘building blocks’ was developed for proof-of-concept, found capable of
achieving several of the proposed configurations.
The outcome of this research is encouraging, with a Massey patent search confirming the
unique features of the proposed concept. The prototype system is an economic, easy to
implement, plug and play, and multiple-configuration robotic manipulator, suitable for
various applications
Minimal knotted polygons in cubic lattices
An implementation of BFACF-style algorithms on knotted polygons in the simple
cubic, face centered cubic and body centered cubic lattice is used to estimate
the statistics and writhe of minimal length knotted polygons in each of the
lattices. Data are collected and analysed on minimal length knotted polygons,
their entropy, and their lattice curvature and writhe
The Compressibility of Minimal Lattice Knots
The (isothermic) compressibility of lattice knots can be examined as a model
of the effects of topology and geometry on the compressibility of ring
polymers. In this paper, the compressibility of minimal length lattice knots in
the simple cubic, face centered cubic and body centered cubic lattices are
determined. Our results show that the compressibility is generally not
monotonic, but in some cases increases with pressure. Differences of the
compressibility for different knot types show that topology is a factor
determining the compressibility of a lattice knot, and differences between the
three lattices show that compressibility is also a function of geometry.Comment: Submitted to J. Stat. Mec
<i>P. berghei</i> telomerase subunit TERT is essential for parasite survival
Telomeres define the ends of chromosomes protecting eukaryotic cells from chromosome instability and eventual cell death. The complex regulation of telomeres involves various proteins including telomerase, which is a specialized ribonucleoprotein responsible for telomere maintenance. Telomeres of chromosomes of malaria parasites are kept at a constant length during blood stage proliferation. The 7-bp telomere repeat sequence is universal across different Plasmodium species (GGGTTT/CA), though the average telomere length varies. The catalytic subunit of telomerase, telomerase reverse transcriptase (TERT), is present in all sequenced Plasmodium species and is approximately three times larger than other eukaryotic TERTs. The Plasmodium RNA component of TERT has recently been identified in silico. A strategy to delete the gene encoding TERT via double cross-over (DXO) homologous recombination was undertaken to study the telomerase function in P. berghei. Expression of both TERT and the RNA component (TR) in P. berghei blood stages was analysed by Western blotting and Northern analysis. Average telomere length was measured in several Plasmodium species using Telomere Restriction Fragment (TRF) analysis. TERT and TR were detected in blood stages and an average telomere length of ~950 bp established. Deletion of the tert gene was performed using standard transfection methodologies and we show the presence of tert− mutants in the transfected parasite populations. Cloning of tert- mutants has been attempted multiple times without success. Thorough analysis of the transfected parasite populations and the parasite obtained from extensive parasite cloning from these populations provide evidence for a so called delayed death phenotype as observed in different organisms lacking TERT. The findings indicate that TERT is essential for P. berghei cell survival. The study extends our current knowledge on telomere biology in malaria parasites and validates further investigations to identify telomerase inhibitors to induce parasite cell death
A simple model of a vesicle drop in a confined geometry
We present the exact solution of a two-dimensional directed walk model of a
drop, or half vesicle, confined between two walls, and attached to one wall.
This model is also a generalisation of a polymer model of steric stabilisation
recently investigated. We explore the competition between a sticky potential on
the two walls and the effect of a pressure-like term in the system. We show
that a negative pressure ensures the drop/polymer is unaffected by confinement
when the walls are a macroscopic distance apart
Paediatric cardiac anaesthesia in sickle cell disease : a case series
Sickle cell disease (SCD) is the most common inherited haematological disorder, producing a mutation of the haemoglobin molecule known as haemoglobin S (HbS). The presence of HbS in the erythrocyte makes it prone to sickling - a process which may lead to vaso-occlusive injury, haemolysis and a hypercoagulable state. Sickling is precipitated by dehydration, hypoxia, hypothermia, acidosis and low flow states. Over time, multi-organ damage develops with significant morbidity and mortality. Paediatric patients with SCD and congenital heart defects may require anaesthesia for corrective cardiac surgery on cardiopulmonary bypass (CPB). During the perioperative period these high-risk patients may suffer significant complications when exposed to the conditions that favour erythrocyte sickling. This case series details our experience of four paediatric patients with SCD patients who underwent corrective cardiac surgery at Red Cross War Memorial Children’s Hospital. The pathophysiology is discussed and the perioperative management of transfusion, cardiopulmonary bypass and temperature regulation is highlighted
Partially directed paths in a wedge
The enumeration of lattice paths in wedges poses unique mathematical
challenges. These models are not translationally invariant, and the absence of
this symmetry complicates both the derivation of a functional recurrence for
the generating function, and solving for it. In this paper we consider a model
of partially directed walks from the origin in the square lattice confined to
both a symmetric wedge defined by , and an asymmetric wedge defined
by the lines and Y=0, where is an integer. We prove that the
growth constant for all these models is equal to , independent of
the angle of the wedge. We derive functional recursions for both models, and
obtain explicit expressions for the generating functions when . From these
we find asymptotic formulas for the number of partially directed paths of
length in a wedge when .
The functional recurrences are solved by a variation of the kernel method,
which we call the ``iterated kernel method''. This method appears to be similar
to the obstinate kernel method used by Bousquet-Melou. This method requires us
to consider iterated compositions of the roots of the kernel. These
compositions turn out to be surprisingly tractable, and we are able to find
simple explicit expressions for them. However, in spite of this, the generating
functions turn out to be similar in form to Jacobi -functions, and have
natural boundaries on the unit circle.Comment: 26 pages, 5 figures. Submitted to JCT
Invloed van luchtvochtigheid op het scheuren van radijs
Referaat Veel gescheurde radijs bij hoge RV tijdens knolvorming In de winter geeft een hoge luchtvochtigheid tijdens de knolvormingsfase duidelijk meer gescheurde radijsknollen. Dit gebeurt met name als de luchtvochtigheid in de eerste teeltfase juist laag is geweest. Dit bleek uit onderzoek bij Wageningen UR Glastuinbouw in Bleiswijk. Bij oogst in januari scheuren radijsknollen veel gemakkelijker dan bij oogst in februari of maart. Vooral bij een knoldiameter van circa 8 mm zijn radijsjes gevoelig voor een hoge luchtvochtigheid. Om in de wintermaanden gescheurde radijs te voorkomen is het dus gewenst dat telers proberen om de luchtvochtigheid tijdens de knolvormingsfase te verlagen door meer te ventileren en/of wat te verwarmen. Abstract High humidity causes more splitting of radish tubers In winter season, high humidity in the greenhouse causes more cracking or splitting of the tubers of radish. This happens especially when humidity in the first growing phase is low. This became clear in a research by Wageningen UR Greenhouse Horticulture in Bleiswijk. Harvesting in January gives far more splitting of radish tubers than harvesting in February or March. Especially tubers with a diameter around 8 mm seems susceptible for splitting at circumstances with a high humidity. Growers are being advised to try to decrease the humidity in glasshouses by ventilating and or heating
On the Relationship Between Uniform and Recurrent Nonuniform Discrete-Time Sampling Schemes
Manufacturing challenges for custom made solar vehicles in South Africa
Solar challenges are designed to test the reliability and efficiency of solar powered vehicles in endurance races. In the past these manufactured vehicles were technology drivers and led to advances in electric motors and solar cell efficiency. The speed in relation to power consumption is one of the main design considerations, with the only energy source being solar power. In the design and manufacturing of these vehicles a number of requirements need to be met in order to pass the safety standards. The Sasol Solar Challenge (SSC) created an opportunity for South African universities to design and manufacture custom made solar powered vehicles. This paper explores and discusses the challenges for manufacturing solar vehicles in South Africa. Key elements like the communication gap between design and manufacturing, the cost of lightweight solar encapsulation, the shortage of local suppliers and expertise in composite manufacturing are evaluated. These insights can be used as foundation for strategic decisions by future stakeholders
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