176 research outputs found
Performance and Emission Parameters of Single Cylinder Diesel Engine Using Castor Oil Bio-Diesel Blended Fuels
The purpose of this study is to investigate the performance and emission parameters of a CI single cylinder diesel engine operating on biodiesel-diesel blends (B0, B5, B10, B15 and E20: 20% biodiesel and 80% diesel by volume). A reactor was designed, fabricated and evaluated for biodiesel production. The results showed that increasing the biodiesel content in the blend fuel will increase the performance parameters and decrease the emission parameters. Maximum power was detected for B0 at 2650 rpm and maximum torque was belonged to B20 at 1600 rpm. The experimental results revealed that using biodiesel-diesel blended fuels increased the power and torque output of the engine. For biodiesel blends it was found that the specific fuel consumption (sfc) was decreased. B10 had the minimum amount for sfc. The concentration of CO2 and HC emissions in the exhaust pipe were measured and found to be decreased when biodiesel blends were introduced. This was due to the high oxygen percentage in the biodiesel compared to the net diesel fuel. In contrast, the concentration of CO and NOx was found to be increased when biodiesel is introduced
Vibration analysis of a small diesel engine using diesel-biodiesel fuel blends
Biodiesel as an environmentally friendly fuel has the potential to provide comparable engine performance results. Biodiesel is a renewable fuel produced from vegetable and seed oils, animal fats or waste edible oils. Sound and vibration caused by the combustion process in the engine might have direct effects on users. One of the important characteristics of diesel fuels is high noise and vibration. The present study was carried out to examine the vibration of different diesel-biodiesel fuel blends in power tiller engine. The main goal was to present fuels with the minimum vibration. So, the time domain signals were analyzed in five levels of engine speed, three axes and six fuel blends on the engine. The signal processing and statistical approach were applied for data analysis. The results showed that in all engine speeds, the dominant frequency is matched to the piston stroke frequency of the engine, as well as the frequency of vibration with the increase of engine speed. The experiments indicated that the magnitude of vibration in the power tiller engine depends on the axis of measurement, engine speed and the fuel blends. Vibration acceleration is significantly affected by engine speed and the increase in forward speed due to the increase in vibration acceleration rms. The results of the experiments revealed that vibration acceleration is significantly affected by the axis of measurement. The magnitude of vibration acceleration in vertical axis was more than that in the other two axes and magnitude of vibration acceleration in the longitudinal axis was more than that in the lateral axis. Fuel blends had significant effect on the vibration. It demonstrated that B100, B5 and B20 have the lowest vibration. On the contrary, B15 and B10 have the highest vibration. Keywords: vibration analysis, power tiller, time domain, frequency domain, diesel-biodiesel fuel blend
Design, Fabrication and Evaluation of Gamma-Type Stirling Engine to Produce Electricity from Biomass for the Micro-CHP System
With consideration of the biomass energy potential, a gamma type Stirling engine with 220cc swept volume and 580cc total volume was designed, optimized and manufactured. The engine was tested with helium. Working characteristics of the engine were obtained within the range of heat source temperature 370- 410˚C and charge pressure 10 bar for biomass resources and heat source temperature 540- 560 ˚C and range of charge pressure 1-12 bar with 1 bar increments at each stage for gases. By using of thermodynamic and heat transfer design methods, the key parameters of the designed Stirling engine like required surfaces for heat transfer were calculated (hot side 307 and the cold side 243 squares of centimeters). For analysis of fluid flow, two-dimensional flow analysis method was performed by the software CFD methods. The principles of thermodynamics as well as Schmidt theory were adapted to use for modeling the engine and then pressure - volume diagrams of the thermodynamic and Schmidt analysis were compared. During the test, the temperature is monitored by thermocouples and the pressure of the working fluid helium is monitored by pressure sensors. Indicated power, friction power and brake power were measured and maximum brake power output was obtained with helium at 550˚C heat source temperature and 10 bar charge pressure at 700 rpm as 96.7 W. Electrical energy produced from biomass sources.Sugarcane bagasse, wood, wheat straw, poplar wood and sawdust as fuel system were selected. Most power be obtained from the sawdust (46 watt) and pruning of trees for wood for low power (21 watts), respectively. Minimum ignition time of the Sawdust (4 min) and the most time flammable wood from pruned trees (10 min) was measured. At maximum power, the internal thermal efficiency of the engine was measured as 16%. The test results confirm the fact that Stirling engines driven by temperature of biomass gases are able to achieve a valuable output power. Results of the present work encouraged initiating design of a single cylinder, gamma type Stirling engine of 1 kWe capacity for rural electrification
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Business model design–performance relationship under external and internal contingencies: evidence from SMEs in an emerging economy
We examined Business Model (BM) designs – performance relationship and the moderating effects of firm age and external environment on this relationship. Furthermore, we investigated the impact of simultaneously operating dual BM designs (i.e. novelty and efficiency) on firm performance and contingent effect of firm age on this relationship. Based on data from 241 Indian SMEs, our findings highlighted that BM novelty was of greater benefit to younger SMEs compared to mature SMEs, while BM efficiency was of greater benefit to more mature SMEs. The environmental dynamism positively moderated the relationship between BM novelty and performance but it negatively moderated the relationship between BM efficiency and performance. We also found that BM efficiency is more beneficial in a low, rather than a high, munificent environment but we found environmental munificence did not moderate the BM novelty and SME performance relationship. Finally, we found simultaneous deployment of BM novelty and BM efficiency resulted in an enhancement of performance among mature SMEs compared to younger SMEs. Our study not only adds to the limited literature on BMs in SMEs but also helps practicing managers and entrepreneurs to make informed choices about their BMs
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Managing Knowledge in Supply Chains: A Catalyst to Triple Bottom Line Sustainability
Sustainable supply chain management (SSCM) has attracted the attention of researchers in recent years. Arguably the interest in SSCM is stimulated by the triple bottom line (TBL) which itself has received significant attention. In addition, knowledge management (KM) and its positive role in improving facets of supply chain development and performance have been topics of interest to academics. Despite all this positive development there is a paucity of theoretical and empirical studies identifying the broad capabilities that affect a firm’s ability to simultaneously pursue economic, environmental and social success. In this paper we use the natural-resource-based view (NRBV) and the knowledge-based view (KBV) to develop a series of propositions linking KM capability to strategic and operational supply chain sustainability and competiveness. We further test the veracity of these propositions by ascertaining the perceptions of 275 practicing managers using a survey instrument. The paper offers a systematic analysis of KM’s role in the development of sustainable supply chain (SSC) strategies and operations respectively. The findings confirm the credibility of a set of theoretical propositions derived from the extant literature, and also identify how different KM processes specifically facilitate strategic or operational development of SSCs. The paper provides researchers with a framework and understanding to guide future research on KM as a catalyst to the TBL in supply chains
Exergy of a hybrid solar-wind reverse osmosis-MSF desalination system
A novel hybrid solar-wind reverse-osmosis (RO) multistage flash (MSF) distillation desalination system was manufac-tured and tested in actual conditions in Iran. Solar energy was used to provide both thermal and electrical power and wind energy was used to provide electrical power. Exergy analysis can be used to design more efficient energy systems by reducing inefficien-cies, and indicates opportunities for improving performance in existing systems. The exergy involved in the hybrid solar-wind RO-MSF desalination system is analyzed below using data obtained from theoretical and experimental studies. The RO and MSF systems, powered by wind and solar energy, achieved increases in the reliability and flexibility of the system and in the quality of the resulting drinking water. According to the exergy analysis, the irreversible losses from the hybrid solar-wind RO-MSF plant are concentrated in the solar collector and the multistage flash chamber. These exergy losses can be reduced by isolating the col-lector, coating the pipes and MSF walls, selecting the parameters for the vapor compressor and RO membrane and pumps, and improving the flash process. By optimizing the performance of the hybrid solar-wind RO-MSF system, the amount of water re-covery should increase, and the energy consumption should decrease, which should improve the overall efficiency of the system. Новая гибридная система многостадийной опреснительной (MSF) ректификационной опреснительной установки с использованием солнечного ветра (RO) была изготовлена ??и испытана в реальных условиях в Иране. Энергия ветра была необходима для обеспечения электрической энергии. Эксергетический анализ может быть использован для разработки более эффективных энергетических систем. Эксергия, задействованная в гибридной системе опреснения RO-MSF солнечного ветра, проанализирована ниже с использованием данных, полученных в результате теоретических и экспериментальных исследований.Системы RO и MSF, работающие от энергии ветра и солнца, гарантируют повышение надежности и гибкости системы. Согласно эксергетическому анализу, необратимые потери от гибридной установки RO-MSF с солнечным ветром сосредоточены в солнечном коллекторе и многоступенчатой ??испарительной камере. Эти параметры могут быть уменьшены за счет изоляции коллектора, покрытия труб и стен MSF, а также улучшения процесса вспышки. Оптимизирующая производительность гибридной системы RO-MSF мощность солнечного ветра должна увеличиваться, а потребление энергии должно снизиться, что должно повысить общую эффективность системы. и улучшение процесса прошивки.Оптимизирующая производительность гибридной системы RO-MSF мощность солнечного ветра должна увеличиваться, а потребление энергии должно снизиться, что должно повысить общую эффективность системы. и улучшение процесса прошивки. Оптимизирующая производительность гибридной системы RO-MSF мощность солнечного ветра должна увеличиваться, а потребление энергии должно снизиться, что должно повысить общую эффективность системы
Relationship between social support with anxiety, depression, and stress in pregnant women attending to health care centers in Zanjan-Iran in 2015-2016
Background: Pregnancy is associated with many emotional, physical, and social changes in women’s lives which may have an effect on the outcomes of pregnancy, so identifying moderating factors such as social support may have a preventing role on unintended outcomes of pregnancy.
Objectives: The purpose of this study was to determine the relationships between social support with anxiety, depression, and stress in pregnant women.
Methods: In this correlational study 249 pregnant women attending to health care centers in Zanjan-Iran, during 2015-2016 were selected using a multi-stage sampling method. Data was collected using three questionnaires including demographic characteristics, Wax social support (social support ftom family, friends, and others) and DASS-21 scale. The data were analyzed using descriptive and inferential statistics with SPSS software version 16.
Results: The average age of the participants were 27.57±5.56 years. The average of total perceived social support of pregnant women was 77.42±10.66, among which the most perceived social support was from the family (29.04%). Data analyses revealed weak negative and significant relationship between total social support and depression (r=-0.17) and stress (-0.13), as well as between social support from others and depression (r=-0.14) in pregnant women (P<0.05).
Conclusion: Although, in this study pregnant women received the most social support from the family, only a weak relationship was found between the total score of social support and social support by others with depression and stress. Therefore, it is recommended that more research be done on the type of social support of Azari pregnant wome
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Competitive Categorization and Networks: Cognitive Strategic Groups
Technological advancement compounds the complexity of competitor identification, making it increasingly multi-front and multi-dimensional. Strategic groups are an important unit for competition analysis, typically delineated by firms’ characteristic similarities or cognitive maps. Both have inadequacies – the former produces methodological artefacts, and the latter is subject to scale limitations, replicability and managers’ cognitive blind spots. Hence, the need for alternatives supplementing the existing approaches. We propose a novel grouping methodology based on news co-mentions, reflecting factual corporate events, executives’ and journalists’ views, and environmental changes. It yields three advantages. First, news depicts interorganizational relationships, alleviating the concern that strategic groups are statistical artefacts. Second, the approach supplements managers’ cognition with that of journalists. Third, the public availability of data offers replicability. The proposed methodology is applied to a sample collected from the US high-tech sector. We document commonalities between the co-mention-based groups and the conventionally used characteristic-based approach. However, the similarity and groups yielded from news co-mentions go beyond characteristic similarities in explaining competitive inclination, suggesting that the co-mention-based approach offers a robust alternative to identifying competitors and strategic groups. Overall, by developing a novel methodology based on a strong theoretical foundation, this study sheds new light on strategic group research
The analytic hierarchy process to support decision-making processes in infrastructure projects with social impact
There is an increasing awareness among all kinds of organisations (in business,government and civil society) about the benefits of jointly working with stakeholders
to satisfy both their goals and the social demands placed upon them. This is particularly the case within corporate social responsibility (CSR) frameworks. In this regard, multi-criteria tools for decision-making like the analytic hierarchy process (AHP) described in the paper can be useful for the building relationships with stakeholders. Since these tools can reveal decision-maker’s preferences, the
integration of opinions from various stakeholders in the decision-making process may result in better and more innovative solutions with significant shared value.
This paper is based on ongoing research to assess the feasibility of an AHP-based model to support CSR decisions in large infrastructure projects carried out by Red
Electrica de España, the sole transmission agent and operator of the Spanishelectricity system
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Combustion characteristics of steam-diluted decomposed ammonia in multiple-nozzle direct injection burner
In line with the decarbonisation of power sector, carbon-free fuels are currently being investigated. In particular, green ammonia or e-ammonia is a candidate fuel which will be playing a key role in many energy-intensive industries. It calls for an in-depth understanding of eFuels combustion characteristics in the fuel flexible combustors. Therefore, the present work for the first time numerically investigates the combustion regimes of steam-diluted, decomposed eNH3 in a novel multi-nozzle direct injection (MDI) burner. Although the MDI burner is not equipped with a conventional swirler, strong flow-flame interaction is observed. The two-layer, angled channels create swirling flows featuring swirl numbers larger than 0.9 in general. The centre recirculation region can help stabilise highly steam-diluted decomposed ammonia with a maximum steam-to-air ratio of 74%. This highest H2% containing, wettest ammonia flame case is found to emit the lowest total emission (NH3+NO + NO2+N2O) of ∼400ppmvd@15%O2 at stoichiometric conditions. The wall heat loss is confirmed responsible for the formation of N2O in distributed flame, suggesting the need of reducing pollution through good chamber wall insulation. However, for flames sitting in the conventional regimes, the impact of wall heat loss is found insignificant. Further, extensive data and flame regime analyses show that NNH can always accurately mark the high heat release region of all types of flames, while OH is only an effective marker for thin flames
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