761 research outputs found
Pressure chamber explosion - Southern African Underwater and Hyperbaric Medical Association statement
Challenges in stakeholders self-organising to enhance disaster communication
Purpose - This paper combines disaster risk reduction (DRR) and communication management literature to investigate the challenges and opportunities encountered when stakeholders spontaneously self-organise communication efforts during a disaster. The 2017 Knysna Fire Disaster in South Africa is used as context. Research methodology - The qualitative, exploratory research was supported by data obtained through thematic analysis of qualitative in-depth interviews and the Facebook page created by the community. Information from the disaster debrief was also included. Findings - The findings suggest that disaster information needs to be sent every 30 seconds to a minute to coordinate rescue and relief efforts. The challenges for disaster management teams to manage this mammoth task and the role that the self-organising community played in assisting the communication process was found not to be recognised in disaster management policies or systems. This adversely affected the work of the disaster management team and stakeholder relationship. Research limitations - This study focussed on one disaster. Future studies could possibly compare various disaster examples to provide even greater insight into the self-organising communicative behaviour of those affected by disasters. Originality/value - The research gives one of the first clear indications of the scope of disaster communication needed during a disaster. It also highlights the community’s ability to contribute to communication management during a disaster, and which is not catered for in the practice, guidelines, or management systems used for disaster management
Strange Particle Production Via The Weak Interaction
The differential cross sections for the neutrino-induced weak charged current
production of strange particles in the threshold energy region are presented.
The general representation of the weak hadronic current is newly developed in
terms of eighteen unknown invariant amplitudes to parametrize the hadron
vertex. The Born term approximation is used for the numerical calculations in
the framework of the Cabibbo theory and SU(3) symmetry. For unpolarized octet
baryons four processes are investigated, whereas in the case of polarized
baryons only one process is chosen to study the sensitivity of the differential
cross section to the various polarizations of the initial state nucleon and the
final state hyperon.Comment: This paper was originally submitted to Physical Review C and
published on 30 August, 201
Assessment of factors that impact on the viability of contract farming: A case study of maize and soya beans in Mashonaland West and central provinces in Zimbabwe
This research analyses factors that affect the viability of contract farming in the Zimbabwean maize and soya sector. The objective was to analyse how sustainability factors (social, ethical, environmental and economic factors) were integrated to ensure the viability and sustainability of contract ventures. A sample of 70 farmers and 4 contracting firms involved in the contract farming production of maize and soya were used. A questionnaire survey and focus group interviews were used as data gathering tools. Quantitative and qualitative data analysis techniques were used and a probit regression model was applied to identify the factors that impacts significantly on the viability of the enterprises. The farmer’s scale, years of experience, availability of inputs, crop grown, production area and access to finances were all identified as the significant factors affecting contract farming viability. It was recommended that farmers refrain from side marketing and contractors stick to contractual agreements in terms of payments and timely provision of inputs.Keywords: contract farming; viability; sustainabilit
PERCEIVED EFFECTIVENESS OF THE LEADERSHIP STYLES OF DEANS IN ETHIOPIAN GOVERNMENTAL TECHNICAL AND VOCATIONAL EDUCATION AND TRAINING (TVET) COLLEGES
The Industrial Development Strategy of 2003 has shown that considerable human resource deficits in Ethiopia are the major reason for the low rate of industrial development. This strategy confirms in its statement: “...education and a training system that is capable of producing the manpower that is both professionally and ethically capable of carrying and sustaining the responsibility of seeing to it that our industrial development program will have achieved its goals” (MOFED, 2003). Therefore, it called for efforts towards quality improvement of the workforce, to reverse the marginalisation of the industrial professions in the TVET system, and to build a culture of entrepreneurship and self-employment (MOFED, 2010). In 2009, the Southern Nations, Nationalities People’s Region (SNNPR) Centre of Competence (COC) conducted standard exams for those who graduated from TVETs. The results were disappointing, as only 12.2% of the TVET graduates and 34.9% of the TVET instructors passed the examinations (SNNPR TVET, 2010). Hence, to solve this chronic problem, high calibre deans should be appointed. In line with this idea, in the year 2003, the World Bank designed a training project to produce and assign skilled leaders in higher education in Ethiopia (World Bank, 2003). Although it failed, it was also the plan of the Ethiopian government that the percentage of TVET leaders trained in leadership would reach 100% in the year 2014 (MOFED, 2010). The TVET sector has particular significance for the reduction of poverty and for the promotion of gender equity because it stresses certain dimensions such as opportunities, skills, human resources development and empowerment. However, in Ethiopia, the Ministry of Finance and Economic Development (MOFED) has introduced an emphasis on developing TVET skills only since the turn of the 21st century. As a result, the MOE has required TVET practitioners not only to link up their knowledge and skills with the past in order to understand the present situation, but also to prompt them to look beyond the present to cope with this dynamic world (MOFED, 2006). The present study assumes importance in finding out perceived effectiveness of the leadership styles of deans in Ethiopian governmental technical and vocational education and training (TVET) colleges. Article visualizations
LEADERSHIP STYLES OF THE DEANS IN ETHIOPIAN GOVERNMENTAL TECHNICAL AND VOCATIONAL EDUCATION AND TRAINING (TVET) COLLEGES
Technological advancements have driven the development of dynamic work environments leading to a need for dynamic and visionary leaders who possess leadership skills and are capable of meeting the challenges and opportunities that exist in the modern workplace that is intent on promoting the change necessary for developing and maintaining the competitive edge (Burke, Stagl, Klein, Goodwin, Salas, Halpin & Winer, 2006). Again, it is even more critical that leaders of the highest calibre are identified, developed, and sharpened within educational institutions. Avolio and Bass (1991) who in their research identified three leadership styles, namely: transformational, transactional, and laissez-faire. They state that these three leadership styles can be used to identify the predictive roles of this range of leader attributes as well as the three outcomes of leadership, namely: extra effort, effectiveness and satisfaction. The FRL is regarded as a contemporary model that has the potential to explain leadership and its multidimensional nature and to measure behaviours empirically that can be used to predict leadership outcomes (Antonakis, Avolio & Sivasubramaniam, 2003; Avolio, 2010). According to Dew (1995) and Northouse (2012), leaders make an attempt to lift up motivation and morale when a transformational leadership style is put into effect. Similarly, Curtin (2004) and Conger and Kanungo (1990) propose that organisations require leadership that stimulates leaders and followers as a result of which observable change can come to the fore. For Avolio (2010), college deans should use the transformational leadership style to be the most successful. The findings of Morgenson, DeRue and Karam (2009), and Ross and Offerman (1991) have suggested that it is advantageous for organisations if they are led by lenient, more nurturing leaders. In his work, Nahavandi (2003) has tried to describe the characteristics of transformational leaders as follows: they work hard to promote self-reliance and optimism about goals and followers' ability, provide a vivid vision, initiate innovation through empowerment and rewards for followers, inspire high expectations by creating a conducive environment and, finally, form and strengthen personal relationships with followers. For Nahavandi (2003), these five characteristics of a transformational leader are of vital importance and the absence of one of these characteristics would make such a leader either ineffective or less effective in terms of his/her leadership. The present study assumes importance in finding out to what extent do the leadership styles adopted by deans have an effect on the government TVET Colleges’ perceived effectiveness as evaluated by deans, teachers, and students. Article visualizations
Brushless direct current motor efficiency characterization
Abstract: The use of a compact lightweight efficient propulsion system is one of the main technological requirements for a long endurance electric Unmanned Aerial Vehicle (UAV). Currently the most popular trend is to use a permanent magnet brushless direct current (BLDC) model motor. This type of motor is used because of its efficiency which can be greater than 90% when optimally driven. However the majority of manufacturers do not provide adequate performance response profiles throughout the specified motor applied voltage range. This paper presents a methodology to characterize the BLDC efficiency
Extending the BASE architecture for complex and reconfigurable cyber-physical systems using Holonic principles.
Thesis (MEng)--Stellenbosch University, 2021.ENGLISH ABSTRACT: ndustry 4.0 (I4.0) represents the newest technological revolution aimed at
optimising industries using drivers such as Cyber-Physical Systems (CPSs), the Internet of Things (IoT) and many more. In the past two decades, the holonic paradigm has become a major driver of intelligent manufacturing systems, making it ideal to advance I4.0.
The objective of this thesis is to extend an existing holonic reference architecture, the Biography-Attributes-Schedule-Execution (BASE) architecture, for complex
and reconfigurable CPSs. In the context of this thesis, complex and reconfigurable systems are considered to be systems that are comprised of many diverse,
autonomous and interacting entities, and of which the functionality, organization or size is expected to change over time. The thesis applies the principles of holonic
systems to manage complexity and enhance reconfigurability of CPS applications.
The BASE architecture is extended for two reasons: to enable it to integrate many diverse entities, and to enhance its reconfigurability. With regards to research on
holonic systems, this thesis aims to address two important functions for systems implemented using holonic principles, namely cooperation and cyber-physical interfacing
The most important extensions made to the architecture were to enable scalability,
refine the cooperation between holons, and integrate cyber-physical interfacing
services as Interface Holons. These extensions include platform management
components (e.g. a service directory) and standardised plugins (e.g. cyber-physical
interfacing plugins). The extended architecture was implemented on an educational
sheep farm, because of the many heterogeneous resources (sheep, camps, sensors,
humans, etc.) on the farm that need to be integrated into a BASE architecture
implemented CPS. This case study implementation had to integrate data from
different sensors, provide live analysis of observed data and, when required, notify the physical world of any problems in the CPS. At the end of the implementation,
an evaluation was done using the requirements of a complex, reconfigurable CPS
as evaluation criteria. This evaluation involved setting up quantitative and
qualitative evaluation metrics for the evaluation criteria, doing the evaluations, and
discussing what the results from the different evaluations indicate about the
effectiveness and efficiency of the extensions made to the BASE architecture.
The extensions made to the BASE architecture were found to improve robustness
and resilience. The use of Erlang was found to play a very important role in the
resulting reliability. The extensions also helped to fully address the original BASE
architecture’s scalability shortcomings and to increase development productivity.
Lastly, the extensions show the benefits of using service orientation to enable
cooperation between holons and how extracting all cyber-physical interfacing of a
system into dedicated Interface Holons reduces development time, improves
reusability and enhances diagnosability of interfacing problems.AFRIKAANSE OPSOMMING: ndustrie 4.0 (I4.0) is die nuutste tegnologiese revolusie en dit is daarop gemik om
industrieë te optimiseer deur middel van drywers soos Kuber-Fisiese Stelsels
(KFSs), die Internet of Things (IoT) en vele meer. In die afgelope twee dekades het
die holoniese paradigma ʼn belangrike drywer van intelligente vervaardigingstelsels
geword, wat dit ideaal maak om I4.0 te bevorder.
Die doel van hierdie tesis is om ‘n bestaande holoniese verwysings argitektuur, die
Biography-Attributes-Schedule-Execution (BASE-) argitektuur, uit te brei vir
komplekse, herkonfigureerbare KFSs. In die konteks van hierdie tesis, word
komplekse en herkonfigureerbare stelsels gesien as stelsels wat bestaan uit menige
diverse, outonome entiteite wat met mekaar interaksie het en waarvan die
funksionaliteit, organisasie en grootte verwag is om te verander met verloop van
tyd. Hierdie tesis pas die beginsels van holoniese stelsels toe om die kompleksiteit
van KFSs te bestuur en om herkonfigureerbaarheid van KFSs te verbeter.
Die BASE-argitektuur word uitgebrei om twee redes, naamlik om die integrasie van
menige diverse entiteite te ondersteun en om die argitektuur se
herkonfigureerbaarheid te verbeter. Die studie sal ‘n navorsingsbydrae lewer oor
holoniese stelsels deur twee belangrike funksionaliteite van stelsels wat
geïmplementeer is deur middel van holoniese stelsels aan te spreek – samewerking
tussen holons en kuber-fisiese koppeling.
Die belangrikste uitbreidings wat gemaak is aan die argitektuur was om
skaleerbaarheid moontlik te maak, samewerking tussen holons te verfyn en om
kuber-fisiese koppelingsdienste te integreer as holons. Hierdie uitbreidings sluit
nuwe platformbestuurkomponente en gestandaardiseerde plugins in. Die
uitgebreide argitektuur is geïmplementeer op ʼn opvoedkundige skaapplaas, omdat
die skaapplaas baie heterogene hulpbronne (skape, kampe, sensors, mense, ens.)
insluit wat in die BASE-argitektuur geïmplementeerde KFS geïntegreer kon word.
v
Hierdie gevallestudie-implementering moes data van verskillende sensors
integreer, intydse analises doen van die waargeneemde data en wanneer nodig, ‘n
entiteit in die fisiese wêreld inlig van enige probleme in die KFS. Aan die einde van
die implementering is ʼn evaluering gedoen deur die vereistes van ʼn komplekse,
herkonfigureerbare KFS as evalueringskriteria te gebruik. Die evaluering het
bestaan uit die opstel van kwantitatiewe en kwalitatiewe evalueringsmaatreëls, die
uitvoer van die evaluerings en ʼn bespreking van wat die evalueringsresultate aandui
oor die effektiwiteit en doeltreffendheid van die uitbreidings wat aan die BASE-
argitektuur gemaak is.
Dit is bevind dat die uitbreidings wat gemaak is aan die BASE-argitektuur
robuustheid en veerkragtigheid verbeter het. Die gebruik van Erlang het ʼn groot rol
gespeel in die gevolglike betroubaarheid. Die uitbreidings aan die BASE-
argitektuur het ook gehelp om die argitektuur volledig skaleerbaar te maak en om
ontwikkelingsproduktiwiteit te verbeter. Laastens, bewys die uitbreidings die
voordele van diensoriëntasie in die samewerking tussen holons en hoe die gebruik
van Koppelings Holons (Interface Holons) ontwikkelingstyd verminder, die
herbruikbaarheid van programbronkode verbeter en diagnoseerbaarheid van
koppelingsprobleme versterk.Master
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