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Case Report
Evaluation of Propellant Slosh Effects and Baffle Requirements in a Hybrid Rocket Oxidizer Tank
Gedlu Solomon*
,
Yishak Tamiru
Issue:
Volume 7, Issue 3, September 2026
Pages:
84-95
Received:
3 June 2026
Accepted:
12 June 2026
Published:
17 July 2026
DOI:
10.11648/j.rd.20260703.11
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Abstract: This paper investigates the necessity of incorporating internal baffles in the oxidizer tank of a vertically launched hybrid rocket employing a regressive fuel grain configuration. The study begins with a review of potential sources of rocket instability, with particular emphasis on propellant slosh and its influence on vehicle stability throughout the flight mission. A systems engineering methodology is adopted to define the mission objectives and establish the corresponding design requirements. These requirements are subsequently decomposed into lower-level requirements and verified through analytical methods to ensure compliance with the overall system objectives. The propulsion system performance is evaluated using NASA Chemical Equilibrium with Applications (CEA) software, considering Hydroxyl-Terminated Polybutadiene (HTPB) as the fuel and Nitrous Oxide (N2O) as the oxidizer at an oxidizer-to-fuel ratio of 8 and a combustion chamber pressure of 30 bar. To characterize the operational environment, the NRLMSIS atmospheric model is employed to obtain atmospheric temperature, air density, and gravity data for 5 May 2026 over an altitude range from sea level to 20 km with 1 km intervals. Based on the derived requirements, preliminary oxidizer tank design activities are conducted, including tank sizing, material selection, wall-thickness determination, and the definition of internal tank features. The dynamic effects of oxidizer motion during flight are analytically evaluated and compared with the stabilizing forces generated by tank ullage pressure. The results demonstrate that the forces induced by oxidizer slosh are significantly smaller than the available stabilizing forces and therefore have a negligible impact on vehicle stability. Consequently, the study concludes that internal baffles are not required for the proposed oxidizer tank design, enabling a simpler and lighter tank configuration without compromising flight stability.
Abstract: This paper investigates the necessity of incorporating internal baffles in the oxidizer tank of a vertically launched hybrid rocket employing a regressive fuel grain configuration. The study begins with a review of potential sources of rocket instability, with particular emphasis on propellant slosh and its influence on vehicle stability throughout...
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Research Article
On-Farm Performance Evaluation of Koekoek Layers Chicken in West Arsi Zone of Oromia, Ethiopia
Issue:
Volume 7, Issue 3, September 2026
Pages:
96-102
Received:
8 April 2026
Accepted:
1 June 2026
Published:
17 July 2026
DOI:
10.11648/j.rd.20260703.12
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Abstract: This study was conducted with the objective of evaluating the egg production performance and egg quality of Koekoek chicken breed under farmer management conditions with locally formulated rations and determines the economic feasibility. Chickens were managed under a semi-scavenging system and supplemented with a locally formulated diet, except for one household which served as a control (no formulated ration). The ingredients used were maize (35%), soybean (20%), wheat bran (19.5%), noug cake (22%), salt (1.5%), premix (1%), and limestone (1%). Each bird received 90 g of the formulated feed daily. A total of 240 Koekoek chickens (200 pullets and 40 cockerels) were distributed and purposive sampling approach was employed to select 20 smallholder farmers (10 from each district) in collaboration with Development Agents, and Kebele leaders. Results showed that formulated ration feeding improved survival rate and egg production performance. Nagele Arsi had a higher survival rate (95%) compared to Kofele (78%). Egg production per hen per year increased with ration, from 122 to 180 eggs in Kofele and from 183 to 222 eggs in Nagele Arsi. While egg quality parameters (egg length, egg width, and yolk color and shell weight) showed no statistically significant differences, egg weight, albumen weight and shell thickness was improved with formulated ration. Formulated ration improved the economic performance of Koekoek layers under farmer management conditions. Farmers perceived Koekoek chickens as more productive when supplemented, less broody, and resilient to disease and predatory compared to local breeds. The study concludes that locally formulated ration improves egg productivity from 153-201, income and survival of Koekoek layer chickens under smallholder management conditions.
Abstract: This study was conducted with the objective of evaluating the egg production performance and egg quality of Koekoek chicken breed under farmer management conditions with locally formulated rations and determines the economic feasibility. Chickens were managed under a semi-scavenging system and supplemented with a locally formulated diet, except for...
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Review Article
Civic Educators' Comprehension of Citizenship and Its Influence on Civic Engagement in Selected Universities and Secondary Schools in Zambia
Issue:
Volume 7, Issue 3, September 2026
Pages:
103-110
Received:
8 February 2026
Accepted:
20 February 2026
Published:
22 July 2026
DOI:
10.11648/j.rd.20260703.13
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Abstract: This study established the Civic Educators' comprehension of citizenship and its influence on civic engagement in selected universities and secondary schools in Zambia. Using a qualitative research approach and descriptive research design. The target population were lecturers and students at University of Zambia, Kwame Nkrumah University and Chalimbana University. The sample size was 30 participants. Inductive thematic analysis was used to analyse data because themes were strongly linked to data. The findings revealed that lecturers had a comprehensive conception of citizenship. They defined citizenship to comprise rights and duties. This aligns with the definition of citizenship as practice and the communitarian theory of citizenship, that takes into consideration both rights and duties as important aspects of citizenship. The teachers and student teachers conceptualised citizenship in terms of belonging and qualification. This conception emphasized rights over duties as per the liberalist theory of citizenship. The study argued that the participants’ comprehension of citizenship influenced their conception of civic engagement in universities and selected secondary schools in Zambia. The findings of the study recommended the need for enhanced Civic education training and curriculum development to foster meaningful civic engagement and understanding of the concept of citizenship. The study also recommended professional development programmes and relevant curriculum reforms.
Abstract: This study established the Civic Educators' comprehension of citizenship and its influence on civic engagement in selected universities and secondary schools in Zambia. Using a qualitative research approach and descriptive research design. The target population were lecturers and students at University of Zambia, Kwame Nkrumah University and Chalim...
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Methodology Article
Pre-Service Social Studies Teachers’ Assessment Literacy in Ghana: A Convergent Triangulation Inquiry
Mohammed Adam*
Issue:
Volume 7, Issue 3, September 2026
Pages:
111-124
Received:
11 April 2026
Accepted:
27 April 2026
Published:
24 July 2026
DOI:
10.11648/j.rd.20260703.14
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Abstract: The study explored how a convergent triangulation mixed-methods design promotes, challenges, and yields a convergent understanding of pre-service Social Studies teachers’ assessment literacy research in a resource-constrained and high-stakes examination environment at the Senior High School (SHS) level in Ghana. The study employed the convergent mixed-methods design grounded in pragmatism. The study was influenced by Vygotsky’s sociocultural theory, the Teacher Assessment Literacy in Practice (TALiP) framework of Xu and Brown, and Greene’s dialectical stance (DS). Using a mixed-purposeful sampling technique, 76 final-year Bachelor of Arts (B. A) in Social Studies Education pre-service teachers at the University of Education, Winneba were selected for the study. Data collection was done using a validated questionnaire, semi-structured interviews, and video-recorded classroom observations. Ferretti et al.’s merging strategy was employed to guide data integration alongside Onwuegbuezie and Johnson’s legitimation framework. The study revealed notable discrepancies between self-reported (questionnaire results) and observed (interview and observation results) assessment literacy (AL). The majority, 7 (70%) of participants demonstrated limited formative assessment practices during lessons, although 85% of them reported high levels of assessment competence. The convergent triangulation design proved valuable in uncovering the discrepancy between theory and practice, revealing the multi-dimensional nature of the pre-service teachers’ assessment literacy (TAL), and producing meta-inferences that neither quantitative nor qualitative approaches alone could yield. The findings, therefore, emphasise the need for context-driven professional development and policy interventions to promote pre-service teachers’ assessment literacy in Ghana.
Abstract: The study explored how a convergent triangulation mixed-methods design promotes, challenges, and yields a convergent understanding of pre-service Social Studies teachers’ assessment literacy research in a resource-constrained and high-stakes examination environment at the Senior High School (SHS) level in Ghana. The study employed the convergent mi...
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Research Article
Responsibility for the Payment of Duties Is Attributed to the Member or to the Company
Armando Luiz Rovai*
Issue:
Volume 7, Issue 3, September 2026
Pages:
125-130
Received:
11 March 2026
Accepted:
7 April 2026
Published:
24 July 2026
DOI:
10.11648/j.rd.20260703.15
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Abstract: This article examines whether the obligation to pay the amount due to a withdrawing, excluded, or deceased member after the partial dissolution of a company rests with the company itself or with the remaining members. Using a doctrinal and case-law-based method, the study analyzes the Brazilian Civil Code, the Code of Civil Procedure, legislation governing legal personality and corporate registration, and recent judicial decisions concerning the valuation and enforcement of equity interests. The analysis distinguishes the company's primary obligation to reimburse the departing member from the residual or secondary liability that may exceptionally reach the personal assets of the remaining members. It also addresses the determination balance sheet, the valuation of tangible and intangible assets at exit value, the relevance of contractual provisions, and the limits of discounted cash flow methods when they incorporate future business expectations. The findings indicate that the amount determined in the valuation procedure constitutes a corporate debt because it corresponds to the pecuniary expression of the departing member's equity interest and ordinarily entails a reduction in the company's net assets or stated capital. Accordingly, enforcement should be directed against the company. Personal liability of a remaining member requires a specific legal basis, such as statutory secondary liability or a duly established disregard of legal personality based on abuse, misuse of purpose, or commingling of assets. The article concludes that preserving the separation between the company and its members promotes legal certainty, protects legitimate reliance on corporate autonomy, and remains compatible with fair valuation and effective payment of the departing member's equity interest.
Abstract: This article examines whether the obligation to pay the amount due to a withdrawing, excluded, or deceased member after the partial dissolution of a company rests with the company itself or with the remaining members. Using a doctrinal and case-law-based method, the study analyzes the Brazilian Civil Code, the Code of Civil Procedure, legislation g...
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