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Plamena Yankova Panayotova, Anatoli Iliev
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 138-144; doi:10.29114/ajtuv.vol4.iss2.217

The present paper focuses primarily on the agrobiological and technological characteristics of the pink local vinous varieties Pamid and Muscat red. Muscat red is a late ripening vinous variety, and variety Pamid is a medium ripening vinous variety with possibility for consumption in fresh condition as well since its pellicle and seeds are not felt, and the titrated acidity is low. Variety Muscat red belongs to the most cold-resistant local varieties. Variety Pamid has increased root phylloxera resistance, on account of which it can be cultivated on its own roots without grafting in sandy soils.
, Darrin Gangemi, Jarod Toogood, Rendage Sachini Sandeepa Chandrasiri
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 91-99; doi:10.29114/ajtuv.vol4.iss2.179

This project was aimed at modelling the stress and deformation profile of a 6061-T6 aluminium suspension upright of a formula society of automotive engineers style vehicle with a double wishbone suspension under the loading conditions of a 1.5G corner. With these results, it would need to be determined whether the design is fit for use. Using remote displacement boundary conditions for the upper and lower wishbone connections and the control arm connection with a remote force at the centre of the wheel patch acting on the bearing surfaces the maximum stress, overall stress profile and maximum deformation of the upright was calculated. These results after, undertaking a verification and validation study, were a maximum equivalent von-Mises stress of 87.358MPa and a maximum bearing surface deflection of 0.21 mm. The maximum von-Mises stress calculated was less than the fatigue limit of 90MPa signalling infinite life and also less than the yield stress of 240MPa signalling a safe design. Verification and validation techniques were used to ensure the final result was accurate and reflected the real – life system. Structural error was used to verify the results where it was found that maximum structural error in the upright was 0.052mJ and at the location of maximum stress was between 0.0058-1.0782e-8 mJ. Validation of the model was achieved by comparing the reaction forces calculated in ANSYS to theoretical values and was found that the magnitudes were within 2.5% of the theoretical values, thus the model was considered valid.
, Asparuh Atanasov, Albena Ivanova, Desislava Mihaylova
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 122-129; doi:10.29114/ajtuv.vol4.iss2.203

The present study observes the development of spring crops maize and sunflower typical of the Southern Dobrudzha region. A distinct methodology for remote monitoring through the use of a small remotely piloted aircraft has been developed for the purposes of the present paper and applied accordingly. Two types of video cameras were used: for the visible range of the RGB light reflected by the plants and for the NearRed reflection close to the red light. The obtained results are presented in both tabular and graphical form and inferred, finally, in the paper are some principal conclusions about the condition of the crops under consideration.
Adebola Adebayo Adekunle, Igba Uvieoghene Tobit, Ogunrinola Oluwaseyi Gbemiga
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 100-111; doi:10.29114/ajtuv.vol4.iss2.177

: Landfill liners are underlying materials with low permeability whose main function is to mitigate the infiltration of toxic contents into ground water lying beneath. Landfill liners are primarily made of bentonite clay. Bentonite has a very low hydraulic conductivity, that might not be readily accessible, unlike kaolin which is found to have a lower hydraulic conductivity compared to that of bentonite and can be extensively obtained from numerous different sources. Explored, for the purposes of the present research paper, were various ratios of bentonite and kaolin and their hydraulic conductivity, in particular ratios of 90:10 kaolin to bentonite, 80:20 kaolin to bentonite, 70:30 kaolin to bentonite, 60:40 kaolin to bentonite and 50:50 kaolin to bentonite in an effort to achieve an acceptable barrier suitable as a liner / where tap water and ammonium solution were used as permeants. It was concluded that the ratios not lower than 20% bentonite (80:20, 70:30, 60:40 and 50:50) all had their hydraulic conductivity value reduced compared to the 100% kaolin.
Ginka Kaleva Marinova, , Nedyalko Nikolov
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 130-137; doi:10.29114/ajtuv.vol4.iss2.204

Distress management is of particular importance in all disease treatment strategies that aim to cope with medical conditions, which require prolonged therapy. Here, we present results obtained in a comparative study of various classification methods for automated distress detection. For the purposes of the present study, use was made of a common experimental protocol that relies on a dataset of approximately 6 000 oncological patients at different stages of therapy. The dataset consists of the binary responses to specific questions in a purposefully-designed self-evaluation questionnaire on the degree of distress. Conducted, within such a framework, was a performance assessment of three distress detectors based on Multilayer Perceptron Neural Network (MLP NN), boosting and bagging meta-classification methods and evaluated, further, was the performance of nine characteristic descriptors (KR1-KR9) representing the informative content of the dataset in different ways. The results obtained in the experiments prove conclusively that one of the characteristic descriptors, KR8 and KR9, significantly outperform the other descriptors in terms of classification accuracy, precision, recall, and F-measure.
Johnson Olufemi Fejoh
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 145-152; doi:10.29114/ajtuv.vol4.iss2.190

Tertiary Education Trust Fund (TETFUND) was established by Federal Government of Nigeria to tackle the problem of inadequate funding of tertiary institutions which had been a major obstacle to the achievement of sustainable developments in these institutions. This study therefore examined the impact of TETFUND interventions on sustainable development goals (research and academic growth and continuous provision of instructional materials and laboratory equipment) of Olabisi Onabanjo University, Ogun State, Nigeria. Descriptive survey research design was adopted and qualitative data were collected using a questionnaire to elicit information from a total number of 250 respondents from total population of 1,723 staff of the university. From the sample size, 128 (56%) were male while 122 (54%) were female. Data collected were analyzed using regression analysis to test all the hypotheses at 0.05 level of significance. Findings revealed that TETFUND interventions have significant impact on sustainable development goals of Olabisi Onabanjo University. It is therefore recommended that Federal Government should step up efforts to ensure that tertiary institutions (federal and state owned) are adequately funded through TETFUND and also do more in the area of human resource development for the research and academic growth of these institutions.
Greg Wheatley, Rendage Sachini Sandeepa Chandrasiri
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 112-121; doi:10.29114/ajtuv.vol4.iss2.180

High density polyethylene (HDPE) is a thermoplastic polymer which is classified as one of the highly consumed types of plastics. One major advantage of thermoplastic materials is their ability of recycling and reprocessing which will bring considerable economicand environmental benefits. The present paper, therefore, endeavours to explore the practical possibility of using recycled HDPE hollow section as a replacement of virgin HDPE made by the extrusion process. The main focus of the study was to evaluate the mechanical performance of the recycled HDPE and compare the results with virgin or non-recycled HDPE. The modulus of elasticity, tensile yield and ultimate strength, compressive yield and ultimate strength, flexural yield and ultimate strength and the coefficient of thermal expansion were the main parameters to be checked against the respective mechanical properties. Thus, pursuant to the rsults, it was found out that the modulus of elasticity and the tensile yield strength are lower in recycled HDPE compared to the non-recycled HDPE. However, there is no significant difference between the recycled and non-recycled HDPE for the tensile ultimate strength, compressive yield strength and compressive ultimate strength. The flexural yield strength and flexural ultimate strength properties of the recycled HDPE proved to be superior to those of the non-recycled HDPE. The coefficient of linear thermal expansion of the recycled HDPE sample was 130 μm/(m.°C) and that for the non-recycled HDPE was 142 μm/(m.°C).
Olori Abiola Lateef, Adedoyin Adewale Adebanjo, Omolola Aminat Ibrahim
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 23-29; doi:10.29114/ajtuv.vol4.iss1.150

The study examined influence of undergraduates’ perceived usefulness and ease of use of mobile technologies on its adoption for learning. Two research questions guided the study. Four hundred (400) students were randomly selected from the two purposively selected universities in Ogun State South West Nigeria. The study employed multiple regressions in the analysis of the data collected. From the result it was found out that undergraduate students’ perceived usefulness (=0.305, t=3.867, p<.05) has significant contribution on the adoption of mobile technologies for learning. Also, it was established that undergraduate students’ perceived ease of use (=0.151, t=1.992, p<.05) has significant contribution on the adoption of mobile technologies for learning. The study concluded that perception of students on the usefulness and ease of use influences adoption of mobile technology for learning. Amongst others, the study recommended the need to encourage undergraduates to adopt mobile technologies for learning instead of social media only.
Svetlana Ivanova Todorova
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 40-54; doi:10.29114/ajtuv.vol4.iss1.165

The unemployment and the issues relating to it refer to the entire population of a given country and that's why they are always relevant. The present article examines the main factors exerting a powerful effect on the unemployment level – the active labour market policy, the labour mobility, the labour productivity and the labor force level. Developed is a theoretical model on the basis of which an empirical analysis is made of the data reflecting the unemployment level in the country over the 2013-2018 period. A special attention is paid to the mutual relation between the unemployment level and the number of the job vacancies, and it is precisely this interdependence that is examined and analysed in the paper using the Beveridge curve.
Georgi Georgiev Georgiev
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 30-39; doi:10.29114/ajtuv.vol4.iss1.162

The paper explores the shape of a fatigue crack initiation in the interval of 106-107cycles of duplex stainless steel, commercially designated as SAF 2507. Particular emphasis is placed upon the development of the crack’s growth front and its subsequent expansion in three directions x, y, z. Created, accordingly, on the basis of the experimentally obtained results, is a 3D computer model to help provide a further prediction for the physical endurance of similar materials. The growth of a fatigue crack is modeled by using The SolidWorks and AutoCAD software tools for constructing the model of fatigue crack growth.
Jamiu Oluwadamilare Amusa
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 79-90; doi:10.29114/ajtuv.vol4.iss1.158

The general apathy towards the study of physics education among the prospective science teachers can once again be raised as the National Open University of Nigeria marks its 15th years of providing functional, cost effective and life-long education to a very large number of Nigerians yearning for university education. Physics Education is arguably one of the few courses that gain the lowest patronage among science students across Nigerian universities. Hence, the discouraging phenomenon of low enrollment is not peculiar to NOUN. The case also becomes more disturbing when the study of physics education in an open and distance-learning environment becomes much more abstract than where you actually see the lecturer each time there is a class as it operates in the conventional university system. The challenge of sustaining physics education in the open and distance environment needs to be addressed towards improving enrollment of students into the programme. The paper has adopted a theoretical approach which examined the sequence of events as regard physics education in the past fifteen years of the existence of the National Open University of Nigeria. The challenges and prospects of this programme, which is at the centre of the nation’s scientific and technological independence were critically x-rayed in the light of current realities. Within the proposed set of recommendations, it was further suggested that the NOUN advocacy team, in collaboration with the Department of Science Education should take sensitization and awareness campaign to secondary school science students particularly on the prospects of enrolling into physics education programme.
Plamen Antonov Stanchev
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 73-78; doi:10.29114/ajtuv.vol4.iss1.174

The paper examines the variation of electrical variables during phase-to-ground faults on medium voltage electrical power lines with a grounded through a resistance neutral. The studies were performed with simulation models of a medium voltage electrical power line. The parameters under consideration have been the voltages and the currents in the transient and steady state operation of the line and more precisely their dependence on the variation of the arc resistance in the place of the fault and the distance from the fault to the supply source. Calculated, accordingly, is the overvoltage during the transient process, the maximum magnitude of the overvoltage and phase-to-earth fault current, the duration of the transient phase-to-ground fault current as well as the maximum magnitude of the overvoltage оn the neutral.
Plamen Antonov Stanchev, Mediha Enver Mehmed-Hamza
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 67-72; doi:10.29114/ajtuv.vol4.iss1.172

In the medium voltage electrical power lines, the most common fault is the phase to ground fault. The determining factors for selection of the neutral grounding mode of the medium voltage electrical power lines are the selectivity of the relay protection, the transient voltages during phase to ground fault, the magnitude of the fault currents, etc. The paper studies the influence of the transient resistance of phase to ground fault on the selectivity and sensitivity of the earth fault protection when the neutral of the power transformer is grounded through active resistance in medium voltage power grids.
Yuri V Novikov, Stas Krasner
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 55-66; doi:10.29114/ajtuv.vol4.iss1.168

Sewing thread cutting processes are widely used in semi-automatic machines of the garment industry, and is an urgent problem. There is no scientifically based methodology for designing thread trimming mechanisms for semi-automatic sewing machines. Cutting threads by the method of scissors does not provide complete cutting of all components of the thread in case of insufficient pressing of the knife planes to each other. To ensure complete trimming, a design cutting scheme has been developed and calculation formulas have been obtained for determining the force exerted by the thread on the movable knife, taking into account the mechanical characteristics of the cut sewing thread.
T. Oluwaseun Lawal, Hannah Olubunmi Ajayi
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 1-11; doi:10.29114/ajtuv.vol4.iss1.127

The study assessed the level of awareness and knowledge of parents and children in the Child Rights Act and determined the level of implementation of Child Rights. The study adopted a survey research design. The population consisted of parents from the major three ethnic groups (Hausa, Igbo, and Yoruba) in Ibadan, Oyo State, Nigeria. The multi-stage sampling procedure was employed for the study. The sample size consisted of 120 parents and 120 children. Two self-designed instruments were administered on the participants. Three research questions were answered and two hypotheses tested. The data obtained were analyzed using frequency count, percentage, and One- Way ANOVA. The results revealed that (51.7%) of parents and (53.3%) of children were aware of the Child Rights Act. It further revealed that 76.7% of parents had a high level of knowledge of Child Rights. It also revealed the level of implementation of some specific rights by the parents. Also, the results revealed that there was a significant difference between the level of awareness and knowledge of parents based on their various tribes at 0.05 significant level(p
Peter Abayomi Onanuga
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 4, pp 12-22; doi:10.29114/ajtuv.vol4.iss1.134

The study investigated the relative effectiveness of generative learning strategy on students’ academic achievement in secondary school Biology. The research design adopted for the study was pre-test, post-test control group quasi-experimental with a 2 x 2 factorial matrix. The groups were crossed with gender as moderating variable to determine its effect on students’ academic achievement. Seventy-six students (76) in the intact classes but purposively drawn from two schools that met a set of criteria constituted the experiment. The research instrument was a 30-item multiple choice test named Biology Achievement Test (BAT) subjected to validity and reliability tests, the test-retest reliability co-efficient yielded 0.78. The data collected were analysed with both descriptive and inferential statistics and the results showed significant main effect of the strategy on students’ academic achievement in senior secondary school Biology. It further revealed that the students exposed to the Generative Learning Strategy (GLS) achieved higher post-test mean achievement score compared to their counterparts exposed to the conventional method. It was recommended among others that the strategy should be integrated into teacher education programme to allow would-be teachers to have adequate understanding and knowledge of its use.
, Albena Ivanova
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 32-38; doi:10.29114/ajtuv.vol3.iss2.141

In June 2019, a drone image recording was performed equipped with an RGB camera on an experimental wheat field at an interval of seven days three times a day. Within one day (12.06.2019) information was collected about the weather conditions and eight measurements were made every hour. The commonly accepted indices were calculated: VARIgreen and ExG for the one-month and one-day observations of the received RGB digitized information. A regression model was created for a full factor experiment of type 23. The interaction of the factors that characterize the conditions of the video was evaluated. Conclusions were formulated as to the influence of the factors under which the observations were made. A recommendation was made with regard to which part of the day it is most appropriate to take photos and video surveillance of wheat.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 54-61; doi:10.29114/ajtuv.vol3.iss2.136

Social phobia is a mental health problem that has been repeatedly linked with adolescents. This study therefore investigated the efficacy of Acceptance and Commitment therapy (ACT) on social phobia among secondary school adolescents in Oyo State, Nigeria. The study adopted a pretest – posttest control group quasi experimental design. The sample comprised of 104 secondary school adolescents identified with some levels of social phobia from the two randomly selected schools among the three senatorial districts of Oyo State. The selected students, grouped by schools and subsequently, treatment groups, were 51 and 53 for the control and experimental groups, respectively. The experimentation spanned a period of eight weeks, with ACT administered to the experimental group and placebo of leadership styles administered to the control group. The Social Phobia Inventory (SPI) was adopted and used for screening and in pretest and posttest stages. A statistical hypothesis was formulated and tested at 0.05 level of significance by means of the Analysis of covariance (ANCOVA). It was found that treatment with ACT significantly reduced the level of social phobia among school-going adolescents. ACT was therefore recommended for use in relieving school-going adolescents suffering from social phobia.
, Olusoji Olurotimi Adewumi, Akinleye Oluyemi Ogundiwin
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 39-53; doi:10.29114/ajtuv.vol3.iss2.139

Methods and strategies traditionally used in teaching science have been described by several researchers as being unsatisfactory and ineffective over many years. Hence, this study examined the effect of Mercedes Model with Embedded Assessment Strategy and Technology on Biology students’ learning outcomes. A pretest-post-test control group, quasi experimental design was adopted for the study. Two purposively selected EDs were randomly assigned to experimental and control groups. Three senior secondary schools were randomly selected from each ED. Altogether, a total of six schools in the two selected EDs were involved in the study. Two intact classes (one science and another non-science) were randomly selected from each of the six schools making a total of twelve classes. In all 568 Senior Secondary Class I biology students formed the sample size. Five instruments were used to generate data for the study, namely, Mercedes Model with Embedded Assessment Strategy and Technology in Diffusion (M2EASTID), Mercedes Model with Embedded Assessment Strategy and Technology in Osmosis (M2EASTIO). Conventional Lesson Plan on Diffusion (COLPOD), Conventional Lesson Plan on Osmosis (COLPO) and Test on Students’ Learning Outcomes in Osmosis and Diffusion (TESLOOD). Four hypotheses were formulated and tested at 0.05 level of significance. Data collected were analysed using frequency counts, means, deviation and analysis of covariance. There was significant effect of treatment on students’ learning outcomes on selected biology concepts. Also, subject specialization has a significant effect on the dependent measures. Mercedes Model with Embedded Assessment Strategies and Technology therefore was effective and significantly improved students’ learning outcomes. Hence, it was recommended that biology teachers in senior secondary schools should adopt Mercedes Model with Embedded Assessment Strategy and Technology for teaching for understanding and application of biology concepts.
Bamikole Oludare Ogunleye, Oluwasogo Ruth Ojo
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 21-31; doi:10.29114/ajtuv.vol3.iss2.145

Poor student achievement in science is a global challenge. Sustainable Development Goals 3 and 4 targeting people’s well-being and quality education as well as previous studies linking physical exercises to improved student memory and increased concentration become relevant. This study, therefore, determined the impact of physical fitness activities on students’ Basic Science achievement. The study adopted pretest, posttest, control group quasi-experimental design. Participants included 125 JS2 students from six schools in Ibadan, Oyo State, Nigeria. Instruments used were stadiometer, gymnasium mats, medicine balls, skipping ropes, cones, stopwatches, weighing scale and Achievement Test in Basic Science (r=.84). The experimental group was exposed to selected science concepts and physical fitness activities simultaneously while the control group was only taught the concepts. Data analysis employed descriptive statistics and Analysis of Covariance. Physical fitness activities had significant effect on students’ achievement (F(1,124)=347.12; P<.05). The experimental group scored higher (x̄=62.58) than control (x̄=53.76). Gender also had significant effect on achievement (F(1,124)=147.89; P<.05) with males performing better (x̄=61.04) than females (x̄=55.29). The interaction effect of treatment and gender on students’ achievement was not significant (F(1,124)=.08; P>.05). Physical fitness activities boosted students’ achievement in Basic Science. Physical fitness activities should, therefore, be implemented in schools.
Ivaylo Vasilev Grancharov
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 62-71; doi:10.29114/ajtuv.vol3.iss2.114

The continuous growth in the volume of liquid cargoes, transported by sea, leads to increase of tankers’ size and to implementation of appropriate shore facilities, which have to meet the relevant environmental requirements. In order to ensure safety during loading and discharging operations in shore terminals, it is necessary to make an assessment on the level of potential risk in port and onboard the vessel and to take all necessary steps to reduce the possibility for environmental impacts and occurrence of an accident especially when performing transfer operations to/from ships. The article presents some constructive decisions for building of shore tanks and their application for storage and transfer of petroleum products. The measures for the safe performing of the cargo operations are systematized after discussing of specifics by performing of all processes connected with loading or discharge. The precautions are defined in three critical points of action - operation on vessel systems, transportation of cargo using shore facilities and storage in tanks.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 1-9; doi:10.29114/ajtuv.vol3.iss2.147

Work engagement is a crucial determinant of university academic staff performance and ultimately of the quality of the provided tertiary education. It is therefore imperative to explore the principal factors it is contingent upon. Equally important is the congruence or the best fit between the personal values and organizational commitment along with the effect of the organizational citizenship behaviour on the work engagement level of the academic staff in South-West Nigerian Universities, which, in turn, provide the appropriate basis for a proper set of recommendations to be developed and put forward to the respective stakeholders. A sample of 382 staff was chosen from the broad range of public universities in South-West Nigeria through the stratified random sampling technique. Use was made of the following data collection tools: the Demographic Data Inventory (DDI), Work Engagement Scale (WES), Organizational Citizenship Behaviour Checklist (OCBC), Personal Values Scale (PVS), and Value Congruence Scale (VCS). Four hypotheses were formulated and tested by means of simple linear regression analysis and Pearson correlation with a significance level of .05. The results obtained reveal not only the significant contribution of organizational citizenship behavior to work engagement (β = .215, t = 12.603, p < .05) but also the decisive role of personal-organisational value congruence in the contribution of organizational citizenship behaviour to work engagement among the academic staff in South-West Nigerian universities.
Bamikole Oludare Ogunleye
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 10-20; doi:10.29114/ajtuv.vol3.iss2.146

Entrepreneurship behaviour is a 21st century attribute required for transforming the industrial and employment space into productive ones. Science students are critical towards the achievement of these requirements. To ensure quality entrepreneurship education, science teachers’ entrepreneurship background and characteristics become germane. This study, therefore, investigated the extent to which science teachers’ entrepreneurship knowledge, attitudes and skills determine their classroom practices in entrepreneurship education in selected Senior Secondary Schools in Lagos, Nigeria. The correlational type of the cross-sectional descriptive research design was adopted. A purposively selected sample of 245 SS2 Science teachers from thirty schools in Lagos mainland, Nigeria participated in the study. Instruments used were: Teacher Entrepreneurship Knowledge Test (r=.86), Teacher Entrepreneurship Attitudes Scale (r=.89), Teacher Entrepreneurship Skills Inventory (r=.85) and Classroom Practices Rating Scale (r=.89). Data were analysed using Pearson Product Moment Correlation and Multiple Regression. Findings showed strong and significant bivariate relationships between each of teachers knowledge (r=.59), attitudes r=.55), skills (r=.52) and classroom practices. The three factors jointly explained 46% of classroom practices with significant relative effects. Teachers require good knowledge, attitudes and skills for effective implementation of entrepreneurship programmes in science education, hence, they need to be exposed to in-service training in entrepreneurial studies.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 40-53; doi:10.29114/ajtuv.vol3.iss1.121

< p align="justify">The current study presents the results from the experimental research conducted on the influence of the regime parameters on the process for a five-dimensional Ball Burnishing (BB) finishing process with the help of a CNC milling machine on the Regular Reliefs (RR) obtained on complex functional surfaces. The elements of the technological system, necessary for the formation of RR of type IV on the complex surfaces, are presented. A planned factorial experiment is realized, through which the significantly affecting parameters of the BB process on the size and shape of the RR cells, are determined. The results obtained are statistically confirmed by a dispersion analysis (ANOVA) carried out. Conclusions, regarding the possibilities of obtaining RRs of type IV on complex surfaces through a process of five-axis simultaneous BB, are made.
Opeyemi Shoaga, Folorunso Ajasa,
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 28-39; doi:10.29114/ajtuv.vol3.iss1.115

This study investigated the effect of three play strategies on academic performance of low achiev-ing Basic 1 pupils in primary schools in Oyo State, Nigeria. A quasi-experimental research design using pretest, posttest, control group was adopted where pupils screened to have low achievement scores were selected from schools randomly assigned to treatment groups. Participants met on dif-ferent treatment strategies for eight weeks of two contact hours each. Academic performance was assessed before and after treatment with data analysed using Analysis of Covariance. Results in-dicated that the three play strategies are effective in improving pupils’ academic performance (F (3 124) = 310.566; p
, Simidele Rasheed
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 21-27; doi:10.29114/ajtuv.vol3.iss1.120

The study examined the influence of socio-economic variables (parents’ income and parents’ educational background) and parental involvement on academic performance of pupils. The survey research design was adopted for the purpose of this study. A sample of 200 pupils in primary four was randomly selected from 10 basic schools for the study. Three research questions were raised and tested for the study. Data were collected using Questionnaire. Data were analysed using Analysis of Variance and Pearson Product Moment Correlation statistics. Significant difference existed in the academic performance of pupils based on their parents’ income while no significant difference existed in the academic performance of pupils based on their parents’ educational background. Furthermore, significant positive relationship was observed between parental involvement and academic performance of pupils. Findings of this study recommends among others that schools managers should develop intervention programmes aimed at addressing the strategies that will help the improvement of the quality and consistency of parental involvement in their children’s education activities if they anticipate better academic performance.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 11-20; doi:10.29114/ajtuv.vol3.iss1.113

This study investigated the effect of emotional intelligence training programme on emotional labour competence of social workers. The study adopted a pretest-post-test quasi-experimental design. The emotional labour scale was used to collect data from the forty-eight (48) randomly selected social workers from two Non-Governmental Organizations (NGOs). Participants of the study were randomly assigned to the treatment and the control groups for the purpose of the study. The hypothesis was tested using the Analysis of Covariant (ANCOVA). Results showed that the treatment significantly affected participants' levels of emotional labour. Based on the findings, it was advocated that the teaching of emotional intelligence in organizations and schools is highly important for optimal outcomes.
, Yekinni Abiodun Oguntimehin, 'Muyiwa Adeyemi
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 3, pp 1-10; doi:10.29114/ajtuv.vol3.iss1.109

This study examined resource mobilisation and innovative culture of small and medium-scale enterprises (SMEs) owners in South-West, Nigeria. Five research questions were raised. The study adopted the descriptive survey research design. The sample comprised one thousand, four hundred and seventeen (1417) SME owners / managers out of which one thousand, three hundred and eighty-two (1382) responded appropriately, this showed 97% response rate. Data were collected using two instruments; these are Resource Mobilisation Questionnaire (r = 0.85) and Innovative Culture Scale (r = 0.68). Data were analysed using descriptive statistics, Pearson Product Moment Correlation and Independent t test.The results showed that SME owners possessed high level of resource mobilisation and innovative culturein South-West, Nigeria. Significant relationship existed between resource mobilisation and innovative culture of SME Owners’ in South-West, Nigeria. Furthermore, there was significant difference in the score on resource mobilisation of SME Owners while no significant difference existed in the score on innovative culture of SME Owners in South-West, Nigeria. Based on the findings, it was recommended among others that Government agencies should create strategies to improve resource mobilisation. This, in turn, will upgrade and enhance innovation among SMEs.
Maciej Sulowski, Ewa Lichańska, Paweł Kulecki, Monika Tenerowicz-Żaba, Anna Staniek
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 1-13; doi:10.29114/ajtuv.vol2.iss2.79

Sintering behavior in high purity nitrogen and mixture of 5% H2-95% N2 of Fe-(Cr)-(Mo)-C system was investigated. The mixtures, differ from chromium, molybdenum and carbon content were prepared in Turbula mixer. Then, using single-action pressing in a rigid die at pressing pressure 400 MPa, green compacts with density level 5.9±0.17 g/cm3 were pressed. Sintering was carried out in a horizontal push rod dilatometer Netzsch 402E at 1120 and 1250°C for 60 min. Heating and cooling rates were 10 and 20°C/min., respectively. After heating, compacts were isothermal sintered at 1120 or 1250°C for 60 minutes an cooled up to 200°C, then isothermally hold for 60 minutes and definitely cooled to the room temperature. Pure nitrogen and mixture of 5% H2-95% N2 were employed as sintering atmospheres. During investigations the influence of isothermal sintering temperature, chemical composition of sintering atmosphere, chromium, molybdenum and carbon content was followed by dilatometry. The aim of investigations was to determine transformation temperatures. It was shown that the dimensional changes occurring during heating and isothermal sintering and the final density of sintered compacts are influenced by sintering parameters and the alloying elements concentration in powder mixture.
Anastas Todorov Yangyozov, Damjanka Stojanova Dimitrova, Lazar Georgiev Panayotov
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 70-79; doi:10.29114/ajtuv.vol2.iss2.95

A small turbine, working with air and water to generate electricity, was designed and its performance was reported in this paper. The rotor diameter is 150mm. The numerical calculations of the power coefficient, torque, and tip speed ratio of turbine were carried out for a wide range of inlet velocities. The flow passing through the turbine was investigated with commercial CFD code ANSYS CFX 18
, , Momchil Todorov Tachev, Kremena Cankova Markova
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 46-53; doi:10.29114/ajtuv.vol2.iss2.91

Bulgaria has been known for its rich history since ancient times. Within its current territory, the country encompasses a variety of cultures that bear their specific specificity and identity. The present study aims at the digitization of models of national and historical value, applying modern technological means. To achieve the goal, a methodical process is used to optimize the interaction of the different working steps.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 54-61; doi:10.29114/ajtuv.vol2.iss2.93

Bulgarian female folk costume is rich in multiple characters, elements and details. One of the most characteristic is the belt buckles. As well as specially designed symbolism, the belt buckle - with their unique identity belong to the national - historical heritage of Bulgaria. In the present study a model of a belt buckle is digitized and reconstructed, and possessing grace and beauty. The realization of the completed three-dimensional computer model goes through stages of photogrammetry and computer design with special sculpting tools.
, Daniela Chakyrova
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 62-69; doi:10.29114/ajtuv.vol2.iss2.94

This paper considers the questions of techno-economic optimization in order to determine the thermal transmittance coefficient of the external walls of an existing residential building.The optimization procedure is conducted for the climatic and economic conditions in Bulgaria and taking into account the existing legal framework. The minimum of the building life cycle costs is determined by using genetic algorithm
Hristina Vasileva Tacheva, Tsena Radkova Murzova
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 80-86; doi:10.29114/ajtuv.vol2.iss2.100

The digital image is an integral part of the contemporary design process. Regardless of the method used to create the image of a conceptual idea /sketch, esquisse/. The result is a digital image, which permits manufacturing, modification and printing. In the design for academic purposes such cases are the majority. This research examines the possibilities for the specific application of 3D scanning in the design of specific complex forms with volume with an artistic character in the field of the award and memorabilia academic system. The application of these technologies noticeably decreases the time needed for design, which is key in such tasks. There is an increase in the precision of the manufacturing of the specific form, as well as a possibility for its printing and modification should the need of other projects, demanding the presence of the same object arise.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 40-45; doi:10.29114/ajtuv.vol2.iss2.90

The hazards of electric arcs in Bulgarian norms, as the Regulations on Health and Safety at work in electrical installations of electrical and thermal power stations and electric power lines and Ordinance №9 on the technical operation of power stations and electric power lines mainly govern the safety at work with high-voltage equipment, are not subject to a special section. NFPA 70E Standards for electrical safety in the Workplace requires to assess whether there are arc-dangers; to calculate the energy released by the arc; to define the permissible arc protection boundaries; to provide adequate personal protective equipment and to label the equipment. The aim of the paper is to summarize the Bulgarian requirements connected somehow with the flash hazard, to compares similarities can be found in approaches to ensuring electrical safety with those of international standards.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 20-39; doi:10.29114/ajtuv.vol2.iss2.88

The paper presents some new chapters of the relativistic circuit theory, which are part of the special theory of relativity. It explores the alternating current regimes in the linear electric circuits, which are moving with very high speeds less than the speed of light. In the paper a large group of basic problems, connected with the relativistic fundamental laws in the time domain and in phasor form for the linear electric circuits are observed. The relativistic forms of the phasors of the basic quantities of the electric circuits (currents, voltages), the complex powers and the relativistic relations of the basic parameters of the circuits (angular frequencies, phases, phase shifts, reactances, susceptances, impedances, admittances) are presented, too. Additionally, some phenomena as resonances and transient processes in fast moving linear electric circuits are observed, as well. All the formulas in the paper are extracted consecutively and they are followed by explanations in full details. The final results are supported by many simple examples about fast moving linear electric circuits.
, Vladimir Georgiev Demirev
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 14-19; doi:10.29114/ajtuv.vol2.iss2.84

A brief analysis has been made about the emergence of the concept of "navigation". The benefits of optimal guidance of agricultural aggregates through GPS navigation are outlined. Some of the positioning accuracy methods that are practiced in agricultural aggregates are analyzed. A poll has been conducted among users of agricultural equipment using GPS navigation. Issue and conclusions are drawn on the benefits and problems for more efficient use of GPS navigation in agriculture.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 39-46; doi:10.29114/ajtuv.vol2.iss1.67

The creation of 3D paper unfolded models with complex geometry requires precision in the design process. Achieving this is through the use of accessible resources and modern technological means which possess the necessary technical and functional capabilities. The successful realization of the models is through the use of a structured methodology containing design stages that are defined in the exact sequence. The present study aims to create the unfoldings of complex three-dimensional models by covering the stages of providing accessible resurses with a personal and commercial license that are transformed in sequence until the ready-made variants.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 30-38; doi:10.29114/ajtuv.vol2.iss1.69

In the description of complex objects, we need methods which could reflect the complex interconnections between components and sift out if possible those of them which are substantial for the specific application. It is offered in this publication the pattern recognition methods should be used as a unified method for processing of data from complex objects. The proposed algorithm may be used in the recognition of the condition of objects of various nature. The indicated examples prove the practical applicability of the methodology as they represent the solution of specific practical problems.
, Krastin Krasimirov Yordanov
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 1-8; doi:10.29114/ajtuv.vol2.iss1.61

This present paper is relevant to the establishment on mathematical model of the heat interaction between the metal matrix (liquid phase- Cu) and a reinforcement (solid- Fe) phase, during the production of the Metal Matrix Composites (MMCs) by the method of capillary molding. In this case is substituted heat object with a mathematical model drawn up and grounded to investigation of the original behavior and properties, clarifies temperature fields in bodies. The established simulation clarifies temperature fields and the causal liaison between the metal matrix and the reinforcement phase in the formation of the macro and microstructure at the time of production of MMCs. Casting process simulation is an approved method for the optimization of the methods of casting technology. The basic opportunities, ideology and structure of the software "MATLAB FEA" are introduced to simulate casting technology. The possibilities of the product are illustrated by the results obtained from a computer simulation by the technical process of the production of MMCs.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 52-60; doi:10.29114/ajtuv.vol2.iss1.72

Each university affirms its reputation in society not only by its scientific and professional achievements but also by certain PR strategies built with the help of well-selected and graphically designed printed and media-based editions, advert messages and signs on billboards and other devices in the sphere of external advertising. The present study of the opportunities offered by nautical sports resources for advertising, popularizing and enhancing the university prestige is part of a theme elaborated in a dissertation. It is also part of building an overall PR strategy.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 47-51; doi:10.29114/ajtuv.vol2.iss1.70

Presented in this article are the author's research on opportunities and restrictions arising from the current level of production equipment and the possibilities of the human operator. The studies are realized on the basis of consultation experience in respect the problems of achieving quality in manufacturing. The classification is proposed on the base of system “man-machine”. Restraint factors are reviewed. Relational to the modern concepts of sustainable development, recommendations are presented to achieve quality in the production process and the preservation of knowledge in the organization.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 17-29; doi:10.29114/ajtuv.vol2.iss1.66

The paper is dedicated to a missing chapter of the circuit theory, which is connected with the special theory of relativity. It is concerned with the direct current regimes in the linear electric circuits, which are moving with speeds smaller than the speed of light or close to it. In it a series of basic questions, connected with the relativistic forms of the fundamental laws for the electric circuits (Kirchhoff’s current law, Kirchhoff’s voltage law, Ohm’s law, Joule’s law, the energy conservation law), are observed. The relativistic forms of the basic quantities of the electric circuits (currents, voltages, powers) and the relativistic relations of the basic parameters of the circuits (resistances, conductances, capacitances, inductances) are presented, too. These formulas are extracted step by step by the help of Maxwell-Hertz-Einstein system of basic equations of the electromagnetic field, which is applied to fast moving objects (linear electric circuits) with arbitrary velocities less than the speed of light or even close to it. The final results are illustrated by the help of some simple examples about fast moving linear electric circuits. Their analyses are presented step by step in order to show the validity of the received relations.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 71-85; doi:10.29114/ajtuv.vol2.iss1.68

The paper offers a review of the linguistic literature dealing with the cognitive approaches to exploring language. It focuses on frame semantics as presenting a systematic description of language meaning and the role of frames in creating conceptual categories. The approaches discussed are applied to a corpus of technical texts and the examples are analysed in terms of the framework suggested.
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 61-70; doi:10.29114/ajtuv.vol2.iss1.74

Virtual Reality does not have to be limited to only being a representation and experiential tool - it can be a powerful way of conceiving objects for our physical world as well. The unique features of this technology revolve around the usage of peripheral devices such as controllers (joysticks) and gloves in tandem with VR goggles. By using this type of modeling, designers can overcome some of the current limitations of the design process such as transitioning from sketch to model, scalability of physical models and manipulation difficulties of computer generated models. An analysis has been made of the evolution of design methodology and its natural progression to virtual and augmented reality. Traditionally the design process of urban design objects starts on paper is evolved through computer modeling and is later tested via physical models and full-scale prototypes. Virtual reality modeling can significantly optimize this process by merging several of the design development phases into one. Sketching, building and testing can be done fully in the virtual environment and the representation of newly created objects will no longer be limited to a 2D surface such as a sheet of paper or a computer screen. The transition to 3D printing is also streamlined with the outcome of the VR designed object being a clear manifestation of the object created in virtual reality. The goal of the study is to develop a piece of urban furniture, using a virtual reality headset, joysticks and modeling software, manipulate its features and multiply/scale it within the digital environment. The research question is whether such modeling can be precise enough to not only be used as a sketching and sculpting tool but can become the next frontier after computer 3D modeling. The experiment is carried out in two different parts of the world simultaneously – USA and Bulgaria and conceived and manipulated in real-time. The results are analyzed and the advantages and disadvantages of the approach are compared to current design development tools.
, Plamen Nedkov Petrov
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 2, pp 9-16; doi:10.29114/ajtuv.vol2.iss1.71

The objectives of this present research work are Cr-containing PM steels sintered in industrial conditions. The sintering was carried out in industrial furnace with 85%N2+15%H2 atmosphere at temperature of T=1140oC, during 40min. It is obtained information about the mechanical properties of the investigated alloys, which serve to further studies connected with the application of chemical heat treatments such as oxidation and gas carbonitriding.
Georgi Petrov Bebrov, Rozalina Stefanova Dimova
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 1, pp 21-26; doi:10.29114/ajtuv.vol1.iss1.27

The paper concerns the quantum cryptography, more specifically, the quantum secure communication type of schemes. The main focus here is on making a comparison between the distinct secure quantum communication models – quantum secure direct communication and deterministic secure quantum communication, in terms of three parameters: resource efficiency, eavesdropping check efficiency, and security (degree of preserving the confidentiality).
Emil Ivanov Panov
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 1, pp 13-20; doi:10.29114/ajtuv.vol1.iss1.22

The paper is dedicated to one of the greatest breakthroughs in the classical physics at the beginning of the 20-th century – the appearance of the special theory of relativity of Albert Einstein in 1905. In it, by the help of the rotary theory, a new proof of the most famous formula in the world – the equation giving the connection between the energy and the mass of the bodies, is presented. Rotary theory appeared in 1998, trying to explain the electromagnetic phenomena from another point of view and to answer to series of questions connected with the basic electromagnetic laws, reaching the same results but giving simpler and direct answers compared with the classical electromagnetic theory of Maxwell. In it, by the help of the method of moments, the vector of the magnetic field intensity and the vector of the magnetic flux density are presented as moments of the vector of the current density of the tangential displacement current , claiming in this way that the magnetic field is a form of rotating electric field. The final result is a set of electromagnetic equations in fully electrical form, depicting all the electromagnetic phenomena from another point of view.
Desislava Yordanova Mincheva, Georgi Stefanov Antonov
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 1, pp 1-5; doi:10.29114/ajtuv.vol1.iss1.23

Recent interest in artificial neural networks has considerably extended their use in the field of powder metallurgy. Advanced in the paper is a model for predicting the micro hardness of sintered compacts made from iron powders and powder mixtures through the process of sintering performed in different atmospheres. The proposed model is based on three layer neural network with backpropagation learning algorithm. Specially developed software has been used to provide for the proper functioning of the neural network. Moreover, it should also be noted that the training data used to carry out the research has been collected by a laboratory controlled experimental testing. Finally, the paper concludes that the presented neural network model is applicable for hardness profile prediction of iron-based sintered alloys as confirmed by the experimental results.
, Sibel Ilhanova Ahmedova
ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, Volume 1, pp 45-51; doi:10.29114/ajtuv.vol1.iss1.39

In the context of increased market competition, SMEs continue to face market and consumption-induced problems related to the acquisition and maintenance of competitive advantages. In this regard, an important factor for the efficiency and improved economic performance of SMEs is the implementation of innovation and the introduction of an active innovation policy. The purpose of the present article is, on the basis of an research analysis, to set out the guidelines for enhancing the innovation activities in the small and medium-sized industrial enterprises.
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