http://ir.haramaya.edu.et//hru/handle/123456789/242 2026-04-17T18:42:22Z http://ir.haramaya.edu.et//hru/handle/123456789/8389 ANALYSIS OF TREATMENT OF THE PRINCIPLE OF NON-RETROACTIVITYINETHIOPIAN INCOME TAX IEGISLATIONS Murtessa Tesgera; (Assis Profer) Kasim Kufa Taxation is a fundamental source of revenue for governments, to provide public goods andadvancing broader development objectives. These objectives are typically achievedthroughthe implementation of policies, strategies, and laws. Legislatures create laws, whichareenforced by the executive and applied by the judiciary. Since laws are intended toguidehuman behavior by setting standards for conduct, they are generally expected to be inplacebefore compliance is required. To fulfill this purpose, laws should operate prospectively, governing future actions rather than retroactively af ecting past behavior. This principleisencapsulated in the doctrine of non-reactivity, which asserts that new laws or legal decisionsshould not apply retroactively, undermining the right to legal certainty and legitimateexpectations built upon prior law. Although retroactive taxation can serve important government interests, there are compelling reasons to impose restrictions. It candisrupt legitimate expectations and undermine trust in the stability of legal frameworks. In Ethiopia, except for criminal legislation, no clear limitations on the retroactive application of incometax laws. Despite the presence of retroactive legislative practices, Ethiopian tax laws remainsilent on the issue. This doctrinal research investigates how non-reactivity is addressedinEthiopia’s income tax system. The paper recommends that retro activity in incometaxlegislation be expressly justified and subject to limitations to balance the government'srevenue needs with the legitimate concerns of taxpayers regarding the uncertaintyandunpredictability of retroactive tax laws. 93p. 2024-09-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8388 EFFECT OF MACHINING PARAMETERS ON THE PERFORMANCE OF EN C60 DURING DRY AND HOT TURNING Dr. Venkatesan Govindarajian; Dr. Habtamu Alemayehu Various machining conditions are utilized to improve the machinability of metals. However, some materials, such as EN C60 carbon steel, are challenging to process conventionally due to their inherent properties. EN C60 is valued for its corrosion resistance and durability under high pressures and temperatures, but its hardness makes it difficult to machine. This study employed a hot machining process to enhance machinability. EN C60 carbon steel and a CNMG120408-BM coated carbide were used as the workpiece and cutting tool. The workpiece was heated in an MR 260E muffle furnace. Experimental parameters included cutting speeds (70, 90, and 110 m/min), feed rates (0.04, 0.08, and 0.12 mm/rev), and temperatures (200°C, 300°C, and 400°C), with a constant depth of cut of 0.50 mm. Taguchi L9 and L27 orthogonal array designs were employed. Responses measured were surface roughness (Ra), material removal rate (MRR), and tool wear using a digital surface roughness tester (VOGEL), a scanning electron microscope (SEM), a digital weight balance, and an analog caliper. Analysis was conducted using Minitab 19 software. Results indicated a high cutting speed of 110 m/min, a low feed rate of 0.04 mm/rev, and a cutting temperature of 200°C produced a better surface finish. Tool wear was higher at cutting speeds of 110 and 70 m/min and a feed rate of 0.12 mm/rev during dry machining compared to hot machining. The highest MRR was achieved at 110 m/min and 0.12 mm/rev, while surface roughness was minimized at low cutting speeds. The chip morphology studied also revealed that at 110.00 m/min cutting speed, 0.04 mm/rev feed rate, and 200°C temperature, the chip thickness was reduced by 16.00% compared to 110.00 m/min cutting speed, 0.04 mm/rev feed rate, and 400°C temperature. A regression-based surface roughness model was developed and found to be adequate, with an R² value of 99.11% 94p. 2025-01-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8274 DESIGN, DEVELOPMENT AND PERFORMANCE EVALUATION OF MANUALLY OPERATED HONEY EXTRACTOR Endryas Sibhat Hailu; Solomon Abera (Dr. Eng.) Ethiopia is one of the countries with a large honey producing potential in Africa. However, its actual annual honey production is limited due to poor methods of harvesting, handling, and extraction. The high cost of imported extractors and the absence of locally available, effective extractors have led to the continued use of traditional extraction methods, which results in suboptimal honey quality and reduced productivity. This study focused on the design, manufacturing and performance evaluation of a manually operated honey extractor. The design integrated a bevel gear system and a chain and sprocket mechanism to ensure minimal power requirement, making the extractor both cost-effective and easy to operate. The extractor was designed to hold eight honeycomb frames and compatible with honeycombs from both traditional and modern hives. Key components of the extractor include a honeycomb holding rotary cage, a traditional honeycomb holding frame, a bevel gear and chain and sprocket driving mechanism, a plastic drum, drum cover, and hand crank. The performance of the honey extractor was evaluated based on extraction efficiency, honeycomb breakage, and extraction capacity under varying operational conditions. A completely randomized design (CRD) at 5 % of significance was employed to analyze the effects of three factors: speed of operation (200 and 300 rpm), extraction time of day (8:30 am and 12:30 pm), and extraction duration (5 and 15 minutes). The study revealed that extraction efficiency ranged from 26.93 to 73.89% at 8:30,5 minute and 200 rpm respectively and from 51.71 to 72.72% at 12:30 pm. Honeycomb breakage was observed only at 300 rpm during the 8:30 am extraction, with a mean breakage rate of 12.50%. Extraction capacity reached a maximum of 29.70 kg/hr at speed of 300 rpm for 5 minutes at 12:30 pm, but decreased with longer durations. ANOVA analysis showed significant effects of speed and time of day on extraction efficiency and capacity. Cost analysis revealed that the extractor, priced at 21,809.01 ETB, incurs an operational cost of 44.74 ETB per hour. Based on the performance evaluation results and cost analysis result, it is concluded that this prototype was easy, efficient, and cost effective solution for Ethiopian beekeepers. 103p. 2024-09-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8211 DESIGN, DEVELOPMENT AND PERFORMANCE EVALUATION OF TRACTOR DRAWN CARROT DIGGER Milkessa Alemu Seyum; Dr. Solomon Abera Carrot is one of the widely produced and consumed root vegetables in Ethiopia. Carrot harvesting was practiced by traditional method using metal hoe, which is characterized by high man-hour requirement, drudgery and considerable losses in terms of root damage and inefficient exposure. Thus, it was important to consider a small horsepower tractor drawn carrot digger for Ethiopian smallholder farmers was designed and fabricated by considering soil, root and machine parameters and performance evaluation of the machine was carried out in the experimental area at Bate Kebele, Haramaya Woreda on farmer’s field. The machine mainly consists of main frame, shank, power transmission system, V-shaped digger blade, eccentric pin and soil separator units. Some physical and mechanical properties of the carrot roots and soils, relevant to the design of the digger were also studied. The experimental design used was factorial randomized block design where speed (2.5, 3 and 3.5km/hr) was the main factor; the rake angle (15o, 20o and 25o) was sub-factor with three replications as a block. The effect of rake angles and forward speeds were evaluated in terms of draft, digging efficiency, damage, soil separation efficiency, field capacity, field efficiency, wheel slip and fuel consumption. The best optimum combination of rake angle and speed to be 20° and 3.5km/hr respectively. At this optimum condition digging efficiency, damage percentage, field capacity, field efficiency, soil separation efficiency and wheel slip were 91.87%, 3.29%, 84.93%, 0.25ha/h, 80.95%, 89.49%, 17.68% respectively. Fuel consumption to finish the one-hectare land and maximum draft force was 17.56l and 6111.4N respectively 100p. 2024-12-01T00:00:00Z