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Issue Info: 
  • Year: 

    2009
  • Volume: 

    7
  • Issue: 

    1
  • Pages: 

    19-26
Measures: 
  • Citations: 

    0
  • Views: 

    450
  • Downloads: 

    243
Abstract: 

Limit to the tension reinforcement ratio in flexural high strength reinforced concrete (HSRC) members is based on the requirement that tension failure as sufficient rotation capacity are ensured at ultimate limit state. However, the provisions for the total amount of longitudinal reinforcement ratio ( r and r¢ ) are not associated with any rational derivation. In this paper, a quantitative measure to evaluate an upper limit to the Compression reinforcement ratio r¢max of flexural HSRC members is proposed. The quantitative criterion to r¢max  can be derived from i) steel congestion and ii) considerations that are related to the diagonal Compression bearing capacity of the members. In this paper it is shown that, when shear loading is dominant, the limit to r¢ is set by the diagonal Compression criterion. Parameters that affect this limit are deeply investigated and the expressions were derived for different end conditions, to provide an additional tool for a better design and assessment of the flexural capacity of HSRC members.

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Issue Info: 
  • Year: 

    2008
  • Volume: 

    21
  • Issue: 

    1 (TRANSACTIONS B: APPLICATIONS)
  • Pages: 

    97-107
Measures: 
  • Citations: 

    0
  • Views: 

    700
  • Downloads: 

    562
Abstract: 

This paper investigates the effect of ethanol-unleaded gasoline blends (E0, E10, E25, E35, and E65) computer interfaced, four-stroke single cylinder Compression ignition engine. The said engine was converted to spark ignition and carburetion to suit ethanol fuel. A suitable provision was provided on the engine to vary the Compression ratio thereby making the engine adaptable to operate at lower Compression ratios. The tests were performed by varying the ignition timing, equivalence ratio, and Compression ratio at a constant speed of 1500 rpm and at wide open throttle (WOT). Effect of ethanolunleadedgasoline blends and tests variables on engine torque and specific fuel consumption were examined experimentally. The results of this investigation, is believed, to contribute substantially to the knowledge, aimed to ensure a secure future energy.

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Issue Info: 
  • Year: 

    2007
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    156-167
Measures: 
  • Citations: 

    0
  • Views: 

    483
  • Downloads: 

    288
Abstract: 

Limit to the tension reinforcement ratio in flexural high strength reinforced concrete (HSRC) members is based on the requirement that tension failure as sufficient rotation capacity are ensured at ultimate limit state. However, the provisions for the maximum amount of Compression reinforcement ratio (r'max) in a doubly reinforced section are not associated with any rational derivation. A quantitative measure to evaluate an upper limit to the Compression reinforcement ratio (r'max) of such flexural HSRC members is proposed. The quantitative criterion to r'max can be derived from i) steel congestion and ii) considerations that are related to the diagonal Compression bearing capacity of the members.In this paper it is shown that, when flexural loading is dominant the shear loading, the limit to ρ' is set by the steel congestion criterion. Parameters that affect this limit such as, f'c, beams geometry (cross sectional dimension and concrete cover), and bars diameter are deeply investigated and the expressions were derived to provide an additional tool for a better design and assessment of the flexural capacity of HSRC members considering different end conditions and loading arrangement.

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Author(s): 

RAJ MOHAN T. | K. KANDASAMY MURUGUMOHAN KUMAR

Issue Info: 
  • Year: 

    2012
  • Volume: 

    3
  • Issue: 

    3
  • Pages: 

    1-8
Measures: 
  • Citations: 

    4
  • Views: 

    530
  • Downloads: 

    192
Abstract: 

Biodiesel can be produced from vegetable oils and also from waste fats. Biodiesel is a mono-alkyl-ester of long chain fatty acids derived from renewable feedstock such as vegetable oils by transesterification process. The esterified cotton seed oil, pungam oil, rice bran oil, and tamanu oil are chosen as the alternative fuels. Among these oils, tamanu oil is considered for the first time as an alternative fuel. An experiment is conducted to obtain the operating characteristics of the variable Compression ratio (VCR) engine run by chosen esterified oils, and the results are compared with esterified tamanu oil. From the comparison of results, it is inferred that the engine performance is improved with significant reduction in emissions for the chosen oils without any engine modification. The effective Compression ratio can be fixed based on the experimental results obtained in the engine since the findings of the present research work infer that the biodiesel obtained from tamanu oil is a promising alternative fuel for direct-injection four-stroke VCR engine.

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Author(s): 

REZAEI K. | BAHRPEYMA F.

Issue Info: 
  • Year: 

    2007
  • Volume: 

    6
  • Issue: 

    4
  • Pages: 

    351-358
Measures: 
  • Citations: 

    0
  • Views: 

    6513
  • Downloads: 

    0
Abstract: 

Background: Chronic diabetes is substantially associated with circulatory disorders in lower limbs. Vacuum-Compression Therapy (VCT) has been commonly used in treatment of peripheral circulatory disorders. VCT is based on intermittent alteration of Positive- Negative pressure phases. The purpose of this study was to determine effects of VCT on diabetic subjects' peripheral blood flow.Methods: In this Before-After and case-series study, 18 type 2 diabetic subjects with diabetic neuropathy and/or peripheral vascular disease (PVD) completed the study. Subjects received 45 min of VCT for 10 sessions three times weekly. Blood flow (calf+foot) was measured via venous occlusion plethysmography.Results: Among Variables of "Arterial Inflow", "Venous Outflow", "Venous Capacity", "Postischemic Reactive Hyperemia" and "Peak Flow of Reactive Hyperemia", only "Venous Outflow" significantly improved after 10 sessions treatment via VCT (P<0.05).Conclusions: Arterial blood inflow, which was the most important determinant evaluated in this study, was not increased via VCT. Additional studies are required to investigate the effective VCT parameters and duration of each session and number of sessions, considering progressive and deteriorative natural history of diabetes.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

LIU DONG | Zhong Dan | Cao Aihong

Issue Info: 
  • Year: 

    2021
  • Volume: 

    18
  • Issue: 

    AB0040
  • Pages: 

    0-0
Measures: 
  • Citations: 

    0
  • Views: 

    37
  • Downloads: 

    21
Abstract: 

Background: Osteoporotic Compression fractures are common among the elderly. It is important to predict the posterior ligamentous complex (PLC) and disc injuries in computed tomography (CT) scans of patients with magnetic resonance imaging (MRI) contraindications. Objectives: To determine the role of the CT Compression ratio (CTCR) in diagnosing PLC and disc injuries and to compare it with the loss of vertebral body height (LOVBH) in osteoporotic thoracolumbar Compression fractures. Patients and Methods: A total of 91 consecutive patients with vertebral fractures were included as the study population. The PLC and disc injuries were assessed using MRI, and the following radiological parameters were determined based on CT scans for further MRI examinations: CTCR, LOVBH, local kyphosis (LK), interspinous widening (ISW), vertebral translation (VBT), and posterior structures fractures (PSF). Statistical analysis was performed to identify the diagnostic value of CT features in PLC and disc injuries. Results: The PLC injuries were detected in 9/91 cases, and the number of disc injuries was 47/91. Neither CTCR nor LOVBH was associated with PLC injuries (P > 0. 05). However, the CTCR was associated with disc injuries (P < 0. 05), with an optimal threshold of 1. 755 (sensitivity, 68. 1%, specificity, 79. 5%), while the LOVBH was not significantly associated with disc injuries. Based on the results, VBT was significantly related to PLC and disc injuries (P < 0. 05). Conclusion: The injured vertebral CTCR was associated with disc injuries rather than PLC injuries, suggesting that Compression fractures are relatively stable with less PLC injury. Overall, CTCR is a useful indicator reflecting the Compression degree of the injured vertebrae, it is also a valid predictor of disc injuries.

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Issue Info: 
  • Year: 

    2020
  • Volume: 

    11
  • Issue: 

    1
  • Pages: 

    8-12
Measures: 
  • Citations: 

    0
  • Views: 

    23
  • Downloads: 

    2
Abstract: 

Rapid development of the global economy demands huge amount of Energy. Transportation sector contributes major part of economy development. Fossil fuels like Petrol and Diesel are used for transportation and heavy duty vehicles. Higher rate of consumption of these naturally available fuels leads to its depletion and deterioration of environment. To solve such issue many researchers are interested in identifying and using alternative fuels for internal combustion engines. Biodiesel is renewable fuel and can be used as alternative fuel for Diesel engines. In present work Canola oil based Biodiesel (COB) is blended in Diesel with different concentration like B20, B40 and B60. Engine input variables like Compression ratio (13:1, 15:1, 17:1) and load (4, 8,12kg) are considered to optimize the results. The Performance of Variable Compression ratio (VCR) Diesel Engine is evaluated using Taguchi method. Analysis of variance is conducted to recognise the significance of input variables on Brake Thermal Efficiency, Brake power Specific Fuel Consumption. Results of optimization showed that load is the most crucial factor which affects the engine performance i.e. Increase in load decrease the Brake Thermal Efficiency, Brake Power and increases the Specific Fuel Consumption.

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Issue Info: 
  • Year: 

    2021
  • Volume: 

    8
  • Issue: 

    1
  • Pages: 

    45-58
Measures: 
  • Citations: 

    0
  • Views: 

    70
  • Downloads: 

    10
Abstract: 

Images Compression is an inevitable part of almost any images processing system, including face recognition systems. One of the main challenges in face recognition systems is reduction of recognition ratio due to the lossy Compression of the images.In this paper, a new approach for face images Compression improve is presented  by producing new quantization tables in JPEG method, using metaheuristic algorithms. The criterion for selecting the best quantization tables is the recognition rate of the compressed images. The new tables not only do not reduce the recognition rate, but also have the ability to increase the Compression ratio at the same time. Experiments have been performed at different intervals of the Compression ratio by adjusting the quality parameter on different sets of the FERET database. The results of the studies indicate that the recognition rate is maintained or in some cases is even increased, despite the increase in the Compression rate.

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Issue Info: 
  • Year: 

    2017
  • Volume: 

    8
  • Issue: 

    3
  • Pages: 

    230-233
Measures: 
  • Citations: 

    0
  • Views: 

    293
  • Downloads: 

    105
Abstract: 

This paper deals with the systematic study of performance evalaution and exhaust emission characteristics of VCR (variable Compression ratio) engine at different Compression ratio and loads using diesel as fuel. Experimental analysis was done to find the optimal value of Compression ratio and load at which the engine can produce higher thermal efficiency, lower specific fuel consumption and low exhaust emission. Performance parameters such as brake mean effective pressure (BMEP), brake thermal efficiency (ɳ bth), brake Specific fuel consumption (BSFC), and exhaust gas emissions like hydrocarbon, carbon monoxide and nitrogen monoxide are considered.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    4
  • Issue: 

    2
  • Pages: 

    183-198
Measures: 
  • Citations: 

    0
  • Views: 

    22
  • Downloads: 

    4
Abstract: 

This paper analyses the VCR (variable Compression ratio) engine's performance, combustion, and emission output responses. The experimental results were modelled using the Grey Taguchi method (GTM) for input parameters of Compression ratio, load, and fuel blends. The objective is to find the optimal combination of input parameters in the minimum number of experiments for minimum emission, better performance, and combustion parameters. The Taguchi’s L9 orthogonal array with GTM is used to get the optimum combination of input parameters. The Taguchi was used to analyze the S/N ratio of experimental data and the gray-based method for optimization of multi-objective to single-objective optimization by assigning the suitable weighting factor to each response. The S/N ratio analysis of grey relational grade (GRG) shows the fuel B10, CR 16, and load at 100% of the optimal input factor level. This optimal level is further confirmed by the TOPSIS method. The analysis of variance (ANOVA) for input to GRG shows the highest influencing factor is the load with a 52.82% contribution, followed by CR at 28.38%, and fuel at 10.52%. The confirmatory results show an improvement of 56.1%. The novelty of this experimentation was to study feasibility of existing engine for alternative fuel with slight modification. At above optimal conditions, this biodiesel can be used efficiently in an unmodified Compression ignition engine.

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