期刊文献+
共找到21篇文章
< 1 2 >
每页显示 20 50 100
Integrating Activity-Based Costing (ABC) and Theory of Constraint (TOC) for Improved and Sustained Cost Management 被引量:1
1
作者 Clayton Kuma 《Journal of Modern Accounting and Auditing》 2013年第8期1046-1058,共13页
Implementing effective cost management approaches has recently gained momentum due to intense competition and increasing customer demands. Moreover, effective cost management approaches have contributed to firms' com... Implementing effective cost management approaches has recently gained momentum due to intense competition and increasing customer demands. Moreover, effective cost management approaches have contributed to firms' competitive advantage in relation to cost leadership strategy. Consequently, firms have implemented contemporary cost management systems, such as activity-based management, business process re-engineering, life-cycle costing, target costing, and theory of constraint (TOC), to enable them to become low-cost producers and compete effectively and sustain their performance. Furthermore, focusing on cost management to improve profitability has led to the integration of activity-based costing (ABC) and TOC. Therefore, the aim of this study is to review literature and discuss how integration of ABC and TOC can result in improved and sustained cost management. While these methods have different approaches in addressing cost management, treating them as complementary cost management approaches can result in improved cost management due to improved product costing, improved cost reporting, improved product-mix decisions, and improved cycle-time management. Improvement in cost management will then result in sustained cost management. Sustained cost management is further enhanced with the investment in information customer and shareholder value technology that supports cross-functional decision making to continue creating to remain competitive in the market. 展开更多
关键词 activity-based costing (ABC) theory of constraint (TOC) cost management cost leadership contemporary cost management systems
下载PDF
Production and purification of a bioactive substance against multi-drug resistant human pathogens from the marine-sponge-derived Salinispora sp.
2
作者 Satyendra Singh Pritesh Prasad +1 位作者 Ramesh Subramani William Aalbersberg 《Asian Pacific Journal of Tropical Biomedicine》 SCIE CAS 2014年第10期825-831,共7页
Objective:To isolate,purify,characterize,elucidate structure and evaluate bioactive compounds from the sponge-derived Salinispora sp.FS-0034.Methods:The symbiotic actinomycete strain FS-0034 with an interesting bioact... Objective:To isolate,purify,characterize,elucidate structure and evaluate bioactive compounds from the sponge-derived Salinispora sp.FS-0034.Methods:The symbiotic actinomycete strain FS-0034 with an interesting bioactivity profile was isolated from the Fijian marine sponge Theonella sp.Based on colony morphology and obligatory requirement of seawater for growth,and mycelia morphological characteristics the isolate FS-0034 was identified as a Salinispora sp.The bioactive compound was identified by using various spectral analysis of ultraviolet,high resolution electrospray ionization mass spectroscopy,H nuclear magnetic resonance,correlated spectroscopy and heteronuclear multiple bond coherence spectral data.A minimum inhibitory concentration assay were performed to evaluate the biological properties of the pure compound against multi-drug resistant pathogens.Results:Bioassay guided fractionation of the ethyl acetate extract of the culture of Salinispora sp.FS-0034 by different chromatographic methods yielded the isolation of an antibacterial compound,which was identified as rifamycin W(compound 1).Rifamycin W was reported for its potent antibacterial activity against methicillin-resistant Staphylococcus aureus,wild type Staphylococcus aureus and vancomycin-resistant Enterococcus faecium and displayed minimum inhibitory concentrations of 15.62,7.80 and 250.00 μg/mL,respectively.Conclusions:The present study reported the rifamycin W from sponge-associated Salinispora sp.and it exhibited appreciable antibacterial activity against multi-drug resistant human pathogens which indicated that sponge-associated Actinobacteria are significant sources of bioactive metabolites. 展开更多
关键词 MARINE ACTINOMYCETES Sponge-derived Salinispora Multi-drug resistant ANTIBACTERIAL RIFAMYCIN
下载PDF
Assessment of Atmospheric Reanalysis Data Based on Buoy Observations over the Tropical Western Indian Ocean in 2019
3
作者 LUO Yulan LIU Lin +6 位作者 PAUL Oloo PHILIP Sagero LI Kuiping YANG Yang SU Qinglei LI Qiuchi MIAO Zichen 《Journal of Ocean University of China》 SCIE CAS CSCD 2023年第4期863-873,共11页
Atmospheric reanalysis data are an important data source for studying weather and climate systems.The sea surface wind and sea level pressure observations measured from a real-time buoy system deployed in Kenya’s off... Atmospheric reanalysis data are an important data source for studying weather and climate systems.The sea surface wind and sea level pressure observations measured from a real-time buoy system deployed in Kenya’s offshore area in 2019 conducted jointly by Chinese and Kenyan scientists were used to evaluate the performance of the major high-frequency atmospheric reanalysis products in the western Indian Ocean region.Compared with observations,the sea level pressure field could be accurately simulated using the atmospheric reanalysis data.However,significant discrepancies existed between the surface wind reanalysis data,especially between meridional wind and the observational data.Most of the data provide a complete understanding of sea level pressure,except for the Japanese 55-year Reanalysis data,which hold a significant system bias.The Modern-Era Reanalysis for Research and Applications,Version-2,provides an improved description of all datasets.All the reanalysis datasets for zonal wind underestimate the strength during the study period.Among reanalysis data,NCEP-DOE Atmospheric Model Intercomparison Project reanalysis data presents an inaccurate description due to the worst correlation with the observations.For meridional wind,most reanalysis datasets underestimate the variance,while the European Centre for Medium-Range Weather Forecasts Atmospheric Composition Reanalysis 4 has a larger variance than the observations.In addition to the original data comparison,the diurnal variability of sea level pressure and surface wind are also assessed,and the result indicates that the diurnal variations have a significant gap between observation and reanalysis data.This study indicates that the current high-frequency reanalysis data still have disadvantages when describing the atmospheric parameters in the Western Indian Ocean region. 展开更多
关键词 Bailong buoy REANALYSIS Indian Ocean sea level pressure surface wind
下载PDF
The Impact of the Environment Management Act (EMA) on the Accountability of Companies in Fiji
4
作者 Glen Finau Jale Samuwai Masilina Rotuivaqali Clayton Kuma Lusiana Kanaenabogi Tevita Veituna 《Journal of Modern Accounting and Auditing》 2013年第9期1216-1234,共19页
This study seeks to explore the impact of the Environment Management Act (EMA) (2005) on the accountability of three companies in Fiji. The study uses a multi-case study approach based on three subsidiaries of a c... This study seeks to explore the impact of the Environment Management Act (EMA) (2005) on the accountability of three companies in Fiji. The study uses a multi-case study approach based on three subsidiaries of a conglomerate. Data collection methods include semi-structured interviews with accountants, internal auditors, and environmental officers, document reviews, and content analysis of annual reports and websites of the respective companies. The findings suggest that the EMA (2005) had some effects in terms of engendering accountability on the companies studied. Further evidence suggests that while this increased accountability has led to disclosures in annual reports and websites, these disclosures are minimal at best; furthermore, they primarily address that the stakeholder group comprised government regulatory authorities. The study provides policy implications on how environmental legislations could be designed to improve the accountability of commercial entities in developing economies. The experience and issues highlighted are also useful to other developing economies who are contemplating in developing their own environmental legislations. This paper is one of the few papers that explore the impact of environmental legislations on accountability in a developing economy context. 展开更多
关键词 environmental legislation Environment Management Act (EMA) sustainability developing economy ACCOUNTABILITY
下载PDF
Cytotoxic and antibacterial substances against multi-drug resistant pathogens from marine sponge symbiont:Citrinin,a secondary metabolite of Penicillium sp. 被引量:6
5
作者 Ramesh Subramani Rohitesh Kumar +1 位作者 Pritesh Prasad William Aalbersberg 《Asian Pacific Journal of Tropical Biomedicine》 SCIE CAS 2013年第4期291-296,共6页
Objective:To Isolate,purify,characterize,and evaluate the bioaclive compounds from the sponge-derived fungus Penicillium sp.FF001 and to elucidate its structure.Methods:The fungal strain FF001 with an interesting bioa... Objective:To Isolate,purify,characterize,and evaluate the bioaclive compounds from the sponge-derived fungus Penicillium sp.FF001 and to elucidate its structure.Methods:The fungal strain FF001 with an interesting bioactivity profile was isolated from a marine Fijian sponge Melophlus sp.Based on conidiophores aggregation,conidia development and mycelia morphological characteristics,the isolate FF001 was classically identified as a Penicillium sp.The bioactive compound was identified using various spectral analysis of UV,high resolution electrospray ionization mass spectra,1H and 13C NMR spectral data.Further minimum inhibitory concentrations(MICs)assay and brine shrimp cytotoxicity assay were also carried out to evaluate the biological properties of the purified compound.Results:Bioassay guided fractionation of the EtOAc extract of a static culture of this Penicillium sp.by different chromatographic methods led the isolation of an antibacterial,anticryptococcal and cytotoxic active compound,which was identified as citrinin(1).Further,citrinin(1)is reported for its potent antibacterial activity against methicillin-resistant Staphylococcus aureus(S.aureus),rifampicin-resistant 5.aureus,wild type S.aureus and vancomycin-resistant Enterococcus faecium showed MICs of 3.90,0.97,1.95 and7.81μg/mL,respectively.Further citrinin(1)displayed significant activity against the pathogenic yeast Cryptococcus neoformans(MIC 3.90μg/mL),and exhibited cytotoxicity against brine shrimp larvae LD_(50)of 96μg/mL.Conclusions:Citrinin(1)is reported from sponge associated Penicillium sp.from this study and for its strong antibacterial activity against multi-drug resistant human pathogens including cytotoxicity against brine shrimp larvae,which indicated that sponge associated Penicillium spp.are promising sources of natural bioactive metabolites. 展开更多
关键词 PENICILLIUM sp. SPONGE derived CITRININ Multi-drug resistant Antimicrobial CYTOTOXIC activity
下载PDF
Identification Scheme for Fractional Hammerstein Models With the Delayed Haar Wavelet 被引量:4
6
作者 Kajal Kothari Utkal Mehta +1 位作者 Vineet Prasad Jito Vanualailai 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2020年第3期882-891,共10页
The parameter identification of a nonlinear Hammerstein-type process is likely to be complex and challenging due to the existence of significant nonlinearity at the input side. In this paper, a new parameter identific... The parameter identification of a nonlinear Hammerstein-type process is likely to be complex and challenging due to the existence of significant nonlinearity at the input side. In this paper, a new parameter identification strategy for a block-oriented Hammerstein process is proposed using the Haar wavelet operational matrix(HWOM). To determine all the parameters in the Hammerstein model, a special input excitation is utilized to separate the identification problem of the linear subsystem from the complete nonlinear process. During the first test period, a simple step response data is utilized to estimate the linear subsystem dynamics. Then, the overall system response to sinusoidal input is used to estimate nonlinearity in the process. A single-pole fractional order transfer function with time delay is used to model the linear subsystem. In order to reduce the mathematical complexity resulting from the fractional derivatives of signals, a HWOM based algebraic approach is developed. The proposed method is proven to be simple and robust in the presence of measurement noises. The numerical study illustrates the efficiency of the proposed modeling technique through four different nonlinear processes and results are compared with existing methods. 展开更多
关键词 FRACTIONAL-ORDER HAAR WAVELET HAMMERSTEIN model nonlinear process OPERATIONAL matrix time delay
下载PDF
Effect of partial blockage of air duct outlet on performance of OWC device
7
作者 S.Patel K.Ram M.Rafiuddin Ahmed 《Journal of Central South University》 SCIE EI CAS 2012年第3期748-754,共7页
The use of a Savonius rotor as turbine for an oscillating water column(OWC) is demonstrated.The effect of tuning the OWC using turbine duct blockage is also studied for different wave conditions.A horizontal turbine s... The use of a Savonius rotor as turbine for an oscillating water column(OWC) is demonstrated.The effect of tuning the OWC using turbine duct blockage is also studied for different wave conditions.A horizontal turbine section OWC employing a Savonius rotor was tested by varying the opening of OWC exit(0%,25%,50%,75% and 100%) to study the behavior and performance of the device.The OWC model was tested at water depth of 0.29 m at frequencies of 0.8,0.9 and 1.0 Hz while the exit openings are varied.The static pressure,dynamic pressure,rotational speed of the Savonius rotor and the coefficient of power are presented as results.The OWC with exit opening of 25% showed greater performance in terms of rotational speed and CP compared to OWC with other exit opening percentages.This proves the ability of the OWC to be tuned by regulating flow in the turbine duct. 展开更多
关键词 oscillating water column wave energy converter wells turbine impulse turbine Savonius rotor
下载PDF
Towards a Standardized Approach of Cetacean Habitat: Past Achievements and Future Directions
8
作者 Nardi Cribb Cara Miller Laurent Seuront 《Open Journal of Marine Science》 2015年第3期335-357,共23页
The understanding of what habitat means for an organism as well as the underlying factors driving patterns of habitat use is still unknown for many species. Cetacean habitat has been described using a range of methodo... The understanding of what habitat means for an organism as well as the underlying factors driving patterns of habitat use is still unknown for many species. Cetacean habitat has been described using a range of methodologies and variables measured over various temporal and spatial scales?that are often author-dependent. However, in order to develop an objective and sound understanding of what habitat actually means for cetaceans, a standardized approach needs to be developed. Here, after briefly reviewing the fundamental differences between terrestrial and marine habitats, we highlight the difficulty in defining a marine habitat, with a special focus on marine mammals. We subsequently provide six recommendations by which future cetacean habitat studies might be approached. This recommended approach aims to amend the way in which we think about and undertake investigations into cetacean habitat. It is believed that through this broadened approach, future cetacean habitat studies will increase our understanding of underlying driving factors of cetacean habitat, rather than just describing distribution patterns. Finally, it is stressed how the proposed approach will be more directly applicable within management frameworks and of benefit to conservation initiatives. 展开更多
关键词 CETACEAN DOLPHINS WHALES HABITAT Modelling Management CONSERVATION
下载PDF
Genotypic Divergence, Photosynthetic Efficiency, Sodium Extrusion, and Osmoprotectant Regulation Conferred Salt Tolerance in Sorghum
9
作者 Ashaduzzaman Sagar Md.Sabibul Haque +12 位作者 Md.Alamgir Hossain Md.Nesar Uddin Jannat E.Tajkia Md.Ashik Mia Toufika Hossain Shabi Md.Solaiman Ali Fakir Md.Abdul Kader Walid Soufan Md.Atikur Rahman Muhammad Aamir Iqbal Mohammad Sohidul Islam Ayman El Sabagh A.K.M.Zakir Hossain 《Phyton-International Journal of Experimental Botany》 SCIE 2023年第8期2349-2368,共20页
Salt stress is one of the major limitations to modern agriculture that negatively influences plant growth and productivity.Salt tolerant cultivar can provide excellent solution to enhance stress tolerance with plantfitn... Salt stress is one of the major limitations to modern agriculture that negatively influences plant growth and productivity.Salt tolerant cultivar can provide excellent solution to enhance stress tolerance with plantfitness to unfavorable environments.Therefore,this study was aimed to screen salt tolerant sorghum genotypes through evaluating of different morphological,biochemical,and physiological attributes in response to salinity stress.In this study,we have been evaluated total six sorghum genotypes including Hybrid sorgo,Debgiri,BD-703,BD-706,BD-707,and BD-725 under salt stress(12 dS m^(-1) NaCl).The response variables included length and weight of root and shoot,root:shoot ratio(RSR),photosynthesis(A),transpiration rate(E),elemental concen-trations(K^(+),Na^(+) and K^(+)/Na^(+)),photochemical efficiency of photosystem II(F_(v)/F_(m)),water use efficiency(WUE)and pigment content(chlorophyll a,and b).The results revealed that saline environment significantly reduced all response variables under study of sorghum genotypes,however,Hybrid sorgo remained unmatched by recording the maximum root and shoot traits.The same genotype recorded higher photosynthetic efficiency which was attributed to Na^(+) extrusion,K^(+) uptake and higher K^(+)/Na^(+) ratio(1.8 at stress),while these mechanisms were not fully active in rest of genotypes.Moreover,this study also implies the involvement of proline in imparting tolerance against saline environment in Hybrid sorgo genotype.Overall,BD-703 remained the most salt sensitive genotype as evident from the minimum morphological growth traits and the least biosynthesis of osmoprotectants.Thesefindings open new research avenues for salt stress alleviation by identifying elite salt-to-lerant genotypes of sorghum for breeding programs. 展开更多
关键词 Salinity tolerance SORGHUM photosynthesis PROLINE ion accumulation genotypic variance
下载PDF
Fault Detection and Test Response Compaction with Array of Two-Input Linear Logic
10
作者 Sunil R. Das Satyendra N. Biswas +2 位作者 Alexander R. Applegate Voicu Groza Mansour H. Assaf 《Journal of Electrical Engineering》 2014年第1期1-11,共11页
The design of space-efficient support hardware for built-in self-testing is of great significance in very large scale integration circuits and systems, particularly in view of the paradigm shift in recent times from s... The design of space-efficient support hardware for built-in self-testing is of great significance in very large scale integration circuits and systems, particularly in view of the paradigm shift in recent times from system-on-board to system-on-chip technology. The subject paper proposes a new approach to designing aliasing-free or zero-aliasing space compaction hardware targeting specifically embedded cores-based system-on-chips for single stuck-line faults extending well-known concept from conventional switching theory, viz. that of compatibility relation as used in the minimization of incomplete sequential machines. For a pair of response outputs of the circuit under test, the method introduces the notion of fault detection compatibility and conditional fault detection compatibility (conditional upon some other response output pair being simultaneously fault detection compatible) with respect to two-input XOR/XNOR logic. The process is illustrated with design details of space compressors for the International Symposium on Circuits and Systems or ISCAS 85 combinational and ISCAS 89 full-scan sequential benchmark circuits using simulation programs ATALANTA and FSIM, attesting to the usefulness of the technique for its relative simplicity, resultant low area overhead and full fault coverage for single stuck-line faults, thus making it suitable in commercial design environments. 展开更多
关键词 Aliasing-free space compaction built-in self-testing in very large scale integration circuits fault detection and conditionalfault detection compatibility system-on-chip.
下载PDF
Optimization of bio-oil production parameters from the pyrolysis of elephant grass (Pennisetum purpureum) using response surface methodology
11
作者 Sunday C.Ikpeseni Samuel O.Sada +6 位作者 Ufuoma J.Efetobor Henry O.Orugba Mathias Ekpu Hilary I.Owamah Jeremiah L.Chukwuneke Solomon Oyebisi Uche P.Onochie 《Clean Energy》 EI CSCD 2024年第5期241-251,共11页
The need to increase bio-oil yield from biomass and enhance its fuel properties has driven research into optimizing the pyrolysis process.This study investigated the influence of three key process parameters—temperat... The need to increase bio-oil yield from biomass and enhance its fuel properties has driven research into optimizing the pyrolysis process.This study investigated the influence of three key process parameters—temperature,heating rate,and nitrogen flow rate—on the pyrolysis of elephant grass(Pennisetum purpureum)in a fixed-bed reactor.Response surface methodology was used to study the im-pact of the aforementioned variables on bio-oil yield to improve its production efficiency.Proximate analysis of the biomass revealed 79.24 wt%volatile matter,14.22 wt%fixed carbon,and 5.86%ash,with ultimate analysis showing 45.44%carbon,5.59%hydrogen,and 40.95%oxygen.The high volatile matter content and favourable carbon and hydrogen percentages indicate that elephant grass is a vi-able energy source due to its potential for high bio-oil yield and energy content.The resulting bio-oil exhibited a higher heating value of 20.9 MJ/kg,indicating its suitability for various heating applications.A second-order regression model was developed for bio-oil yield,with optimal conditions identified as a temperature of 550°C,a heating rate of 17°C/min,and a nitrogen flow rate of 6 ml/min.The study achieved an optimal bio-oil yield of 59.03 wt%,and the model’s high R²value of 0.8683 from analysis of variance analysis confirmed its predictive accuracy.This research highlights elephant grass as a sustainable feedstock for bio-oil production,offering valuable insights into optimizing pyrolysis conditions to enhance bio-oil yield,thus advancing biofuel technology. 展开更多
关键词 renewable energy BIOMASS sustainable feedstock regression model fixed-bed reactor
原文传递
Effect of front guide nozzle shape on the flow characteristics in an augmentation channel of a direct drive turbine for wave power generation 被引量:4
12
作者 Deepak PRASAD Mohammed Asid ZULLAH +1 位作者 Mohammed Rafiuddin AHMED Young-Ho LEE 《Science China(Technological Sciences)》 SCIE EI CAS 2010年第1期46-51,共6页
There is an increasing interest in cross flow turbines(also known as Banki turbines) for small and low head applications because of their simple structure as well as low capital and maintenance costs.The present work ... There is an increasing interest in cross flow turbines(also known as Banki turbines) for small and low head applications because of their simple structure as well as low capital and maintenance costs.The present work aims at implementing the direct drive turbine(DDT) of cross flow type for wave power generation.A numerical wave tank was used to simulate the waves and after obtaining the desired wave properties;the augmentation channel plus the front guide nozzle and rear chamber were integrated to the numerical wave tank.The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet.The inlet which was modeled as a plate wall moved sinusoidally with the general function x = asinω t.The augmentation channel consisted of a front nozzle,rear nozzle and an internal fluid region which represented the turbine housing.The front and rear nozzles were geometrically the same.Three different front guide nozzle configurations were studied:a standard guide nozzle which was originally attached to the augmentation channel and two other front guide nozzles of different geometries.The purpose of this study is to observe how the front guide nozzle shape influences the flow downstream,mainly in the augmenta-tion channel,water power and the first stage energy conversion.The analysis was performed using a commercial CFD code ANSYS-CFX.The results of the flow in the augmentation channel for the three front guide nozzles are presented in this paper. 展开更多
关键词 numerical WAVE TANK WAVE POWER augmentation channel direct DRIVE TURBINE water POWER
原文传递
空间数据仓库的安全控制
13
作者 Govorov M Khmelevsky Y +3 位作者 Ustimenko V A Khorev A 厉彦玲 王吉军 《导航定位学报》 2004年第1期11-13,共3页
安全在任何数据库访问和数据传输应用里都是一个重要的问题,尤其是在Internet环境下。基于Web的地理空间数据的安全问题和地理空间数据这个整体一样。
关键词 数据仓库 空间数据 数据安全
下载PDF
Performance analysis of a wave energy converter using numerical simulation technique 被引量:4
14
作者 Mohammed Asid ZULLAH Deepak PRASAD +1 位作者 Mohammed Rafiuddin AHMED Young-Ho LEE 《Science China(Technological Sciences)》 SCIE EI CAS 2010年第1期13-18,共6页
A general purpose viscous flow solver Ansys CFX was used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank.This paper presents the results of a computational fluid dynamics(CFD) analys... A general purpose viscous flow solver Ansys CFX was used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank.This paper presents the results of a computational fluid dynamics(CFD) analysis of the effect of blade configuration on the performance of two Savonius rotors for wave energy extraction.A piston-type wave generator was incorporated in the computational domain to generate the desired incident waves.A complete OWC system with a 3-bladed Savonius rotor was modeled in a three dimensional numerical wave tank and the hydrodynamic conversion efficiency was estimated.The flow over the rotors was assumed to be two-dimensional(2D),viscous,turbulent and unsteady.The CFX code was used with a solver of the coupled conservation equations of mass,momentum and energy,with an implicit time scheme and with the adoption of the hexahedral mesh and the moving mesh techniques in areas of moving surfaces.Turbulence was modeled with the k-e model.The results indicated that the developed models are suitable to analyze the water flows both in the chamber and in the turbine.For the turbine,the numerical results of pressure and torque were compared for the two cases. 展开更多
关键词 wave energy Ansys CFX CODE SAVONIUS ROTOR NUMERICAL simulation TORQUE efficiency
原文传递
Influence of Carbon Content on Strain Hardening Behaviour of Sintered Plain Carbon Steel Preforms 被引量:1
15
作者 S Narayan A Rajeshkannan 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第9期33-40,共8页
Complete experimental investigation on the instantaneous strain hardening behaviour of powder metallurgy (P/M) preforms of pure iron, Fe 0.35%C, Fe-0.75%C and Fe-1.1%C was carried out. The strain hardening be haviou... Complete experimental investigation on the instantaneous strain hardening behaviour of powder metallurgy (P/M) preforms of pure iron, Fe 0.35%C, Fe-0.75%C and Fe-1.1%C was carried out. The strain hardening be haviour of the above-mentioned P/M sintered steel preforms with aspect ratio of 0.4 under triaxial stress state condition was determined by cold upsetting under nil/no and graphite lubricant conditions. The instantaneous strain hardening value (ni), strength coefficient (Ki), and the stress as a function of strain and densification were obtained and analyzed. Furthermore, a relation was obtained from a semi-log plot of stress against relative density and analyzed to study the hardening behaviour owing to densification as stress was a function of induced strain as well as densification in the P/M materials. 展开更多
关键词 strain hardening exponent density hardening exponent strength coefficient DENSIFICATION triaxial stress
原文传递
Experimental studies on the flow characteristics in an inclined bend-free OWC device 被引量:1
16
作者 Krishnil Ravinesh Ram Mohammed Rafiuddin Ahmed +1 位作者 Mohammed Asid Zullah Young-Ho Lee 《Journal of Ocean Engineering and Science》 SCIE 2016年第1期77-83,共7页
A bend-free rectangular cross-section OWC device was designed and constructed for studying the effect of inclination on the flow characteristics inside the device.The inclination is meant to reduce reflection of waves... A bend-free rectangular cross-section OWC device was designed and constructed for studying the effect of inclination on the flow characteristics inside the device.The inclination is meant to reduce reflection of waves and induce higher velocities in the turbine section.Experimental measurements were made in a wave channel where the OWC device was tested.An S-type Pitot tube was used to measure dynamic pressure of air in the turbine section at several inclinations.Particle Image Velocimetry(PIV)was also done to study the flow of both air and water in the OWC device.In order to focus solely on primary energy capture,no turbine was installed in the OWC device.The dynamic pressure readings were analysed for suction and compression stages.Water volume fluctuations inside the capture chamber were also recorded and compared for different inclinations.The result was an increase in the velocity of air flowing in the capture chamber and hence a rise in the kinetic energy available to the turbine.It was found from experimental studies that as the angle of inclination reduced,the velocity of air in the turbine section increased.The lower angles also caused higher run-up and larger volume of water into the capture chamber. 展开更多
关键词 Oscillating water column Particle Image Velocimetry Wave energy.
原文传递
Workability Studies in Forming of Sintered Fe-0.35CPowder Metallurgy Preform During Cold Upsetting
17
作者 S Narayan A Rajeshkannan 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第12期71-78,共8页
An experimental investigation on the workability behaviour of sintered Fe-0.35C steel preforms under cold upsetting,have been studied in order to understand the influence of aspect ratio and lubrication condition on t... An experimental investigation on the workability behaviour of sintered Fe-0.35C steel preforms under cold upsetting,have been studied in order to understand the influence of aspect ratio and lubrication condition on the workability process.The above mentioned powder metallurgy sintered preform with constant initial theoretical density of 84% of different aspect ratios,namely,0.4 and 0.6 respectively were prepared using a suitable die-set assembly on a 1 MN capacity hydraulic press and sintered for 90 min at 1200 ℃.Each sintered preform was cold upset under nil/no and graphite frictional constraint,respectively.Under the condition of triaxial stress densification state,axial stress,hoop stress,hydrostatic stress,effective stress and formability stress index against axial strain relationship was established and presented in this work.Further more,attained density was considered to establish formability stress index and various stress ratio parameters behaviour. 展开更多
关键词 powder metallurgy failure analysis plastic behaviour WORKABILITY
原文传递
Recent introduction of an allodapine bee into Fiji: A new model system for understanding biological invasions by pollinators
18
作者 Scott V. C. Groom Marika V. Tuiwawa +1 位作者 Mark I. Stevens Michael P. Schwarz 《Insect Science》 SCIE CAS CSCD 2015年第4期532-540,共9页
Morphology-based studies have suggested a very depauperate bee fauna for islands in the South West Pacific, and recent genetic studies since have indicated an even smaller endemic fauna with many bee species in this r... Morphology-based studies have suggested a very depauperate bee fauna for islands in the South West Pacific, and recent genetic studies since have indicated an even smaller endemic fauna with many bee species in this region resulting from human-aided dispersal. These introduced species have the potential to both disrupt native pollinator suites as well as augment crop pollination, but for most species the timings of introduction are unknown. We examined the distribution and nesting biology of the long-tongued bee Braunsapis puangensis that was first recorded from Fiji in 2007. This bee has now become widespread in Fiji and both its local abundance and geographical range are likely to increase dramatically. The impacts of this invasion are potentially enormous for agriculture and native ecosystems, but they also provide opportunities for understanding how social insect species adapt to new environments. We outline the major issues associated with this recent invasion and argue that a long-term monitoring study is needed. 展开更多
关键词 Allodapini exotic species Fiji long distance dispersal pollinatorcompetition
原文传递
Studies on a low Reynolds number airfoil for small wind turbine applications 被引量:9
19
作者 Joji WATA Mohammed FAIZAL +3 位作者 Boniface TALU Lesia VANAWALU Puamau SOTIA M.Rafiuddin AHMED 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第7期1684-1688,共5页
In contrast to large horizontal axis wind turbines (HAWTs) that are located in areas dictated by optimum wind conditions, small wind turbines are required for producing power without necessarily the best wind conditio... In contrast to large horizontal axis wind turbines (HAWTs) that are located in areas dictated by optimum wind conditions, small wind turbines are required for producing power without necessarily the best wind conditions. A low Reynolds number airfoil was designed after testing a number of low Reynolds number airfoils and then making one of our own; it was tested for use in small HAWTs. Studies using XFOIL and wind tunnel experiments were performed on the new airfoil at various Reynolds numbers. The pressure distribution, C p , the lift and drag coefficients, C L and C D , were studied for varying angles of attack, α. It is found that the airfoil can achieve very good aerodynamic characteristics at different Reynolds numbers and can be used as an efficient airfoil in small HAWTs. 展开更多
关键词 low Reynolds number AIRFOIL small wind turbines pressure distribution coefficient of lift coefficient of drag
原文传递
Performance studies on an oscillating water column employing a Savonius rotor 被引量:2
20
作者 Sandeep K PATEL Krishnil RAM +1 位作者 M.Rafiuddin AHMED Young-Ho LEE 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第7期1674-1679,共6页
A new oscillating water column (OWC) design is proposed in this study to incorporate a simpler Savonius type turbine. Conventional OWC devices employ a bi-directional turbine such as a Wells or an Impulse turbine to e... A new oscillating water column (OWC) design is proposed in this study to incorporate a simpler Savonius type turbine. Conventional OWC devices employ a bi-directional turbine such as a Wells or an Impulse turbine to extract energy from the air. The disadvantages of the Wells turbine include its inability to self start and stalling. The Savonius turbine is much cheaper and is an effective option at low Reynolds numbers. In the current rectangular OWC device, unlike the circular OWC, the width of entry of the capture chamber can be increased without being influenced by the diameter at the turbine section. To improve its primary capture efficiency, the front and rear walls of the OWC are inclined to minimize reflection. The Savonius rotor characteristics are studied with respect to the change in frequency of the incoming waves. The rotor rpm is sensitive to wave period and primary conversion efficiency while changes in depth only affect the rotor rpm at lower frequencies. The Savonius rotor shows promising results and can be incorporated into large scale OWC devices to reduce costs of the turbine component of the system. 展开更多
关键词 wave energy Savonius rotor oscillating water column inclined chamber
原文传递
上一页 1 2 下一页 到第
使用帮助 返回顶部