bluuebunny/crossref_metadata_2025 huggingface dataset:
FEA Simulation Based Performance Study of Multi Speed Transmission Gearbox
Authors: Kumar Ashwani , Patil Pravin P.
Published: January 2016

The main objective of this research work is to investigate the performance of automobile transmission gearbox under the influence of thermal properties variation of gearbox lubricant. An assumption has been made that the air-gear oil mist within transmission is under steady state condition, in isothermal equilibrium with the transmission gear oil bath of lubricant. The lubrication in multi speed transmission is subjected to thermo-elastohydrodynamic lubrication. The study here analyzed transmission in second gear pair. In full torque loading condition the high temperature generated due to meshing action of gears and frictional conditions between the transmission gear train changes the thermo-physical property of gear oil. The overall vehicle transmission gearbox performance is governed by the gear oil properties and it also effects the fuel consumption. This research study was performed at two higher different temperature range of gear oil.The analysis result shows that the gearbox oil thermal properties directly effect the performance and life span of automobile transmission gearbox.
Improvement in Power Efficiency of Injection Molding Machine by Reduction in Plasticization Losses
Authors: Khan Muhammad , Khan Nizar Ullah , Aziz Muhammad Junaid , Ullah Hafiz Kaleem , Shahid Muhammad Ali
Published: January 2016

This paper discusses the losses in injection molding machine specifically in the plasticization phase. Highest power consuming process is identified and a solution is proposed to reduce the losses and transient-thermal Finite Element Analysis (FEA) is performed for verification purpose. The results of analysis are in good agreement with the theoretical calculations. The analysis presented here provides an understanding that how injection system can be redesigned in order to be more energy efficient.
Exploring Causes, Taxonomies, Mechanisms and Barriers Influencing Knowledge Transfer
Authors: Hasnain Sheikh Shamim , Jasimuddin Sajjad M. , Fuller-Love Nerys
Published: January 2016

Knowledge transfer is one of the significant elements in the knowledge management process. Knowledge transferors share different types of knowledge with the recipients with a view to fulfilling the latter's knowledge needs. The importance of identifying the appropriate knowledge transfer mechanisms and the barriers to knowledge transfer are paramount. However, neither the knowledge management literature nor the NGO-sector literature has adequately addressed the issues of causes of knowledge transfer, taxonomies of knowledge, mechanisms and barriers of knowledge transfer in comprehensive way in the context of the Bangladeshi NGO sector. The highest number of NGOs in the world is deployed in Bangladesh. Little is known about such transfer within the NGO context based in Bangladesh. This paper makes an endeavour to bridge these grey areas of knowledge management and NGO-sector. Having collected the qualitative data from Bangladeshi NGOs and using the content analysis technique, the study identified the causes of knowledge transfer, taxonomies of knowledge, mechanisms of knowledge transfer and the barriers to knowledge transfer in the context of Bangladesh. By understanding the mechanisms and the determinants of knowledge transfer, company and NGO managers and public policy makers can influence knowledge transfer more effectively. Future researchers may extend this study by carrying out similar research in a different context.
Knowledge Management in a Global Context
Authors: Bookhamer Paul , (Justin) Zhang Zuopeng
Published: January 2016

This paper establishes a formal framework of managing knowledge assets in global enterprises. The suggested framework holistically integrates the following eight components: global information infrastructure, IT capabilities, global outsourcing, global information system design, development, and implementation, trans-border data flow, IT cultures, global virtual teams, and information resource management strategies, which serve as the crucial enablers of the success of knowledge management initiatives in a global context. Validated by a case study, the proposed framework provides meaningful insights for future research and valuable guidance for practicing managers of global knowledge management.
Numerical Study of Mixed Convection through Horizontal Duct Utilizing Al2O3
Authors: Om Nur Irmawati , Mohammed Hussein A.
Published: January 2016

In the present study, mixed convection in a horizontal rectangular duct using Al2O3 is numerically investigated. The effects of different Rayleigh number, Reynolds number and radiation on flow and heat transfer characteristics were studied in detail. This study covers Rayleigh number in the range of 2 106 ≤ Ra ≤ 2 107 and Reynolds number in the range of 100 ≤ Re ≤ 1100. Results reveal that the Nusselt number increases as Reynolds and Rayleigh numbers increase. It was also found that the dimensionless temperature distribution increases as Rayleigh number increases.
Effects of the Position of Kitchen Hood Suction on Thermal Comfort and Carbon Dioxide Gas Emission from an Urban Residential Kitchen in Developing Countries
Authors: Hamidur Rahman M. , Sadrul Islam A.K.M.
Published: January 2016

In this study, a typical kitchen having a standard dimension of 213cm × 243cm × 305cm was modeled with single open door exit. Steady state simulations were performed using three dimensional commercial CFD solver with appropriate boundary conditions. Two heat sources were used for modelling the kitchen that resembles the double burner gas stoves of urban residential kitchen in developing countries. In the earlier works, for the same model the predictions validated at an optimum grid resolution and the results have been presented for thermal comfort, carbon dioxide gas emission under natural, forced and no ventilation cases. The effect of kitchen hood system on the thermal comfort and emission has also been analyzed. In this present work, three different positions of the kitchen hood suction have been studied for the effect on thermal distribution and emission rate. The investigated positions of the kitchen hood are the Front, Top and Bottom with respect to the gas stove. It was observed that both front and bottom hood extraction method significantly reduces the emissions to well below the safe limit. They also can maintain thermal comfort quite well inside the kitchen space.
Simulation of Dynamical Performance of Solar Desiccant Cooling Cycle
Authors: Assadi Morteza Khalaji , Mohammadi Ali
Published: January 2016

In this research, solar desiccant cooling cycles in ventilation and hybrid mode are simulated. To simulate cycles, at first a model for desiccant wheel simulation is presented and a computer code based on experimental correlations is used to solve equations. Then by TRNSYS software a model for solar hot water system is simulated, and eventually by representing a suitable algorithm, computer program for simulating solar desiccant cooling cycles by EES software is developed. For all components of desiccant cycle, the dynamic optimum were based on regeneration temperature and solar fraction, and after optimum, dynamic cycle performance in an office building with an area of 115 m2 located in Bushehr city, capacity of cooling 3 ton refrigeration were analyzed. The results show that solar desiccant cooling cycles in comparison with compression refrigeration cycles with 40% saving in energy consumption and also during the day and in office buildings have a better performance.
Binder Influence on the Water Adsorption Uptake of Silica Gel
Authors: Li Ang , Thu Kyaw , Sabnani Karan M. , Ng Kim Choon
Published: January 2016

The heat transfer rate of an adsorbent embedded heat exchanger can be significantly improved by as much as three folds using powder adsorbent coated by binder on the fin surfaces of exchangers. The overall performance of such exchangers in an adsorption chiller, however, is determined both by the heat transfer and adsorption mass transport phenomena, which are also highly interlaced in the chiller operations. If a severe suppression on the latter is observed as a result of the binder, the heat exchanger may eventually underperform. This work evaluates the overall effect of the binder on the mass transport. It focuses on a common adsorbent-adsorbate pair utilized in the chiller, i.e. silica gel type 3A-water. A hydroxyethyl cellulose (HEC) is used as the binder. Experiment is conducted to measure the water equilibrium uptake of the pure and binder added silica gel at various temperatures. Based on the results, the net influence of the binder on the water uptake rate in the adsorption heat transfer process is determined.
Characteristics of Two-Phase Flow Heat Transfer of R-22 and R-290 in Horizontal Circular Small Tube
Authors: Pamitran Agus Sunjarianto , Khabibah Ulfi , Mohd-Ghazali Normah , Ahmad Robiah , Saito Kiyoshi
Published: January 2016

Hydrocarbon refrigerants have been widely used to replace HFCs. As hydrocarbon, R-290 has no ODP (Ozone Depletion Potential) and negligible GWP (Global Warming Potential). This paper presents flow boiling heat transfer in small tube with R-290 and R-22. The test tube has inner diameter of 7.6 mm and length of 1.07 m. In order to determine the heat transfer coefficient, experiments were carried out for heat fluxes ranging from 10 to 25 kW/m2, mass fluxes ranging from 204 to 628 kg/m2s, and saturation temperatures ranging from 1.87 to 11.9o C. The study analyzed the heat transfer through the local heat transfer coefficient along the flow under the variation of these different parameters. In comparison with R-22, R-290 provides higher heat transfer coefficients. In the prediction of the heat transfer coefficients of R-22 and R-290, the correlation of Shah (1982) and Choi et.al. (2009) best fitted the present experimental result, respectively.
Performance Analysis for Vehicle Air Conditioning System with Direct Current Compressor in Non-Electric Vehicle Using Fuzzy Logic Controller
Authors: Dahlan Afiq Aiman , Haziqah Zulkifli Amirah , Nasution Henry , Aziz Azhar Abdul , Mohd Perang Mohd Rozi
Published: January 2016

Reducing fuel consumption and ensure occupants thermal comfort are two important considerations when designing a vehicle air conditioning system. By using direct current electric compressor, speed of compressor can be controlled by changing the frequency of the inverter. Fuzzy logic controller (FLC) was developed to imitate the performance of human expert operators by encoding their knowledge in the form of linguistic rules. The system is installed to a 5-door compact car with 1.2cc four-cylinder engine with data acquisition system to monitor the temperature of the cabin, coefficient of performance (COP) and fuel consumption. Temperature set-point of 22°C with original belt-driven, on/off and FLC electric direct current compressor at one hour experimental periods. The experimental results indicate that the FLC can save more fuel compared to on/off controller and belt-driven compressor.
Progress in Wind Environment and Outdoor Air Ventilation at Pedestrian Level in Urban Area
Authors: Abd Razak Azli , Hagishima Aya , Awang Sa Zainol Abidin , Zaki Sheikh Ahmad
Published: January 2016

This paper reviews the progress made in outdoor wind environment and outdoor ventilation at pedestrian level in urban area for the past few decades until today. The focus is on the effect of wind on people at pedestrian level and how the urban geometry can influence the flow field around the building. Section 1 explains the effect of natural wind environment on comfort and safety of the pedestrian. Section 2 describes the characteristic of pedestrian wind and flow pattern around the building due to the building geometry arrangement.
Low Temperature Waste Heat Driven Refrigeration Cycle
Authors: bin Ismail Azhar , Ang Li , Thu Kyaw , Ng Kim Choon
Published: January 2016

This work explores the utilization of alternative refrigerants to the conventional silica gel + water adsorption pair for the adsorption chiller cycle. Water as the working fluid in the cycle limits the cooling temperatures to above 0°C due to its triple point. The activated carbon Maxsorb III is thus considered as the adsorbent due to its high micro-porous characteristics which lead to higher uptake values. The isotherms of this adsorbent with natural refrigerant Propane, n-butane as well as refrigerants HFC-134a, R507a and R-32 are fitted to the Dubinin-Astakhov equation and the parameters tabulated. With these isotherms, the performances of these pairs with respect to their Specific Cooling Effects (SCE) are compared for assorted cooling temperature, ambient temperature and waste temperature requirements. It was found that the natural refrigerant propane exhibits the most favorable operational conditions when the required cooling temperature is below 0°C. A mathematical model is thus developed to predict the cycle of the propane cycle and is found to show a good fit to the experimental results.
A New Approach for Ignition Timing Correction in Spark Ignition Engines Based on Cylinder Tendency to Surface Ignition
Authors: Ghanaati Ali , Said Mohd Farid Muhamad , Mat Darus Intan Zaurah , Andwari Amin Mahmoudzadeh
Published: January 2016

The performance of Spark Ignition (SI) engines in terms of thermal efficiency can be restricted by knock. Although it is common for all SI engines to exhibit knock from compressed end-gas, knocks from surface ignition remains a more serious problem due to its effect on combustion stability and its obscurity to detect. This paper focuses on predicting the occurrence of knocks from surface ignition by monitoring exhaust gas temperature (EGT). EGT measured during an engine cycle without the spark plug firing. Therefore, EGT rises illustrated any combustion made by surface ignition. Modelling and simulation of a one-dimensional engine combustion done by using GT-Power. The new approach reduces the complexity as EGT monitoring does not require high computational demands, and the EGT signals are robust to noise. The method is validated against a variety of fuel properties and across engine conditions. A new approach is proposed as a measure to predict and detect the knock events.
Preliminary CFD Investigation of Syngas Combustion at Different Operating Pressure
Authors: Mat Zian Norhaslina , Hasini Hasril , Om Nur Irmawati
Published: January 2016

Study on the flow and combustion behavior inside gas turbine combustor used in thermal power plant is described in this paper. The combustion process takes place using synthetic gas and emphasis is given to the effect of pressure variation on flame profile, temperature distribution and emissions as compared to the conventional combustion using methane. The operating pressure of the can-type combustor varies in the range of 1-10 atm. while the syngas composition is assumed to have fixed values of 10% CH4, 55% CO, 30% H2 and 5% N2. Preliminary result shows that the flow inside the can-combustor is highly swirling which indicates good mixing of fuel and air prior to the entrance of the mixture to the main combustion zone. The temperature distribution at combustor mid plane show identical pattern for pressure range between 1-10 atm for both maximum and average temperature magnitude.
Hydrate Formation in Two Phase Flow in Pipe
Authors: Pao William , Hashim Fakhruldin M. , Baheta Aklilu Tesfamichael , Seng Sook Harn
Published: January 2016

Hydrate formation occurs in pipelines beyond sea water depth of 3000 ft. with uniform ocean temperature of 38-40oF, and pressure as low as 100 psig. Plugged-up leads to pressure drop and decreased flow rate, disrupting crude oil transportation. This paper reported the detailed investigation of hydrates particles diameters and interfacial area density in relation to the hydrate deposition in deepwater pipeline. The work focused on the pipe bend section where there is an abrupt change of flow momentum. The flow was assumed isothermal and constant mean hydrate particle size. It was found that initial hydrate particulates’ diameter has the most significant impact on the deposition thickness, causing significant increase of thickness in comparison to other factors. It is concluded that the prevention of hydrate plugging should focus primary on controlling the hydrate’s mean particle sizes.
Experimental Analysis of Impedance-Driven Reverse Flow Dynamics
Authors: Lee V.C.C. , Chai Chang Hong , Law Ming Chiat , Wee S.K.
Published: January 2016

Impedance pump is a type of valveless pumping device, in which it utilizes a bio-inspired mechanism for pumping of fluid based on resonant wave interactions along a flexible media. By inducing a periodic asymmetrical compression on the flexible media will produce a unidirectional flow within the system. The impedance pump has many beneficial characteristics which make it an effective driving mechanism, especially for micro-fluidic systems. In addition, the wave-based mechanism through which pumping occurs infers many benefits in terms of simplicity of design and manufacturing. Adjustment of simple parameters such as the excitation frequency or compression location will reverse the direction of flow, providing a very versatile range of flow outputs. This paper describes the experimental analysis of such impedance-driven flow with emphasis on dynamical study of the reverse flow in open-loop environment. In this study, tapered section with converging steps is introduced at both ends of the flexible media to amplify the reverse flow. Study conducted shows that the reverse peak flow is rather significant with estimate of 23% lower than the forward peak flow. The flow dynamics on the other hand has shown to exhibit different characteristics as per the forward peak flow.
Effects of Two-Phase Flow Friction Factor Correlations on the Optimal Pressure Drop-Martinelli Parameter Pair in a Mini-Channel
Authors: Mohd Ghazali Normah , Pamitran Agus Sunjarianto , Jong-Taek Oh , Ahmad Robiah , Rabin Muhammad Khairul Fitkry
Published: January 2016

Substantial research has been completed with more on-going on the flow pattern and heat transfer associated with two-phase flows. Discrepancies reported may have been as much as agreements, due to the different models, approaches, flow regimes, correlations, and new working fluids being utilized. This paper reports the outcome of a study to look at the effects of applying two different friction factor correlations on the simultaneous minimization of the pressure drop and Martinelli parameter under optimized flow rate and vapor quality, using genetic algorithm. The homogeneous model is assumed with ammonia as the working fluid, the coolant being environmentally friendly and having recently discovered as a potential replacement for the current refrigerants in micro and mini-channels. Results show that significant differences in the frictional pressure drop and Martinelli parameter arise due to the different correlations used, and this is only the outcome from two different correlations currently being considered by researchers in pressure drop analysis for two-phase flows in mini-channels. Thus, absolute agreement is indeed not possible between theoretical, experimental, and numerical work in view of the many different available correlations being utilized today with differences between 10 to 100 percent that has already been established.
Numerical Study on Fluid Structure Interaction of Slug Flow in a Horizontal Pipeline
Authors: Mohmmed Abdalellah Omer , Nasif Mohammad Shakir , Al-Kayiem Hussain Hamoud , Al-Hashimy Zahid Ibrahim
Published: January 2016

It is well-known that when slug flow occurs in pipes it may result in damaging the pipe line. Therefore it is important to predict the slug occurrence and its effect. Slug flow regime is unsteady in nature and the pipelines conveying it are indeed susceptible to significant cyclic stresses. In this work, a numerical study has been conducted to investigate the interaction between the slug flow and solid pipe. Fluid Structure Interaction (FSI) coupling between 3-D Computational Fluid Dynamic (CFD) and 3-D pipeline model code has been developed to assess the stresses on the pipe due to slug flow. Time – dependent stresses results has been analyzed together with the slug characteristic along the pipe. Results revealed that the dynamic behavior of the pipelines is strongly affected by slug parameters. The FSI simulation results show that the maximum stresses occurred close to the pipe supports due to slug flow, where the pipe response to the exerted slug forces is extremely high. These stresses will subsequently cause fatigue damage which is likely reduce the total lifetime of the pipeline. Therefore a careful attention should be made during the design stage of the pipeline to account for these stresses. The system has been investigated under multiple water velocities and constant air velocity, the maximum stress was obtained at the water velocity of 0.505 m/s. Moreover, when the water velocity is increased from 0.502 to 1.003 m/s the maximum stress magnitude is decreased by 1.2% and when it is increased to 1.505 m/s the maximum stress is diminished by 3.6%.
Simulation of Unsteady Incompressible Flow Using a New Particle Method
Authors: Ng Khai Ching , Mohd Yusoff Syamimi , Hwang Yao Hsin , Sheu Tony Wen Hann , Yusoff Mohd Zamri
Published: January 2016

A new particle method, namely the Moving Particle Pressure Mesh (MPPM) method is developed to compute incompressible single- and multi-fluid flows. Unlike the conventional particle method (such as SPH and MPS) whereby the pressure variable is associated with individual moving particle, the pressure is treated as a field (or Eulerian) variable due to the fact that there is no transport equation of pressure can be expressed for an incompressible moving fluid particle. A more accurate method can then be easily devised to evaluate the pressure gradient, which is important in governing the subsequent motion of individual fluid particle. The method is applied to compute several incompressible flow cases and the numerical results agree considerably well with the reference solutions.
Design, Simulation and Fabrication of Polydimethylsiloxane (PDMS) Microchannel for Lab-on-Chip (LoC) Applications
Authors: Abidin Ummikalsom , Majlis Burhanuddin Yeop , Yunas Jumril
Published: January 2016

Microchannel of micron-to milimeter in dimension has been immensely used for fluid handling in transporting, mixing and separating biological cells in Lab-on-Chip (LoC) applications. In this paper, design, simulation and fabrication of Polydimethylsiloxane (PDMS) microfluidic channel are presented. The microchannel is designed with one inlet and outlet. A reservoir or chamber is proposed as an extra component in the microchannel design for ease of separating the intended biological cells as used in LoC magnetic separator and micro-incubator. Finite Element Analysis (FEA) shows laminar flow characteristic is maintained in the proposed microchannel design operating at volumetric flow rate between 0.5 to 1000 μL/min. In addition, pressure drop data across the microchannel are also been obtained from the FEA in determining the safe operation limit of the microchannel. The PDMS microchannels of two different chamber geometries have been successfully fabricated using replica molding technique from SU-8 negative photoresist mold. The fabricated SU-8 mold and the PDMS microchannel structure dimension are characterized using Scanning Electron Microscopy (SEM). Reversible bonding of PDMS microchannel layer and PDMS tubing layer has successfully accomplished by activating the PDMS surfaces using corona discharge. The preliminary testing of the microchannel confirmed its function for LoC continuous flow applications.
Characterization of Flat Sheet Pd/Ag Membrane Using Pure Hydrogen
Authors: Faizal Hasan Mohd , Kawasaki Yuki , Yokomori Takeshi , Ueda Toshihisa
Published: January 2016

The permeation characteristic of a flat sheet Pd/Ag membrane was investigated experimentally by using pure hydrogen. A 77wt.%Pd/23wt.%Ag membrane with 25μm thickness and 0.02m diameter was used. The hydrogen permeation mole flux was investigated under various reference membrane temperatures (423-723K), for upstream pressures of 0.21-0.29MPa, and feed flow rate of 1.39x10-4mol/s. In all cases, the downstream pressure was set at atmospheric. Experimental results demonstrate the linear relationship between the hydrogen permeation flux and difference in square root of hydrogen partial pressure between the upstream side and downstream side, regardless of reference temperatures. This indicates the compatibility of the Pd/Ag membrane used in the present study with Sieverts’ Law. At sufficiently low temperature level, the hydrogen permeation flux is found to be very sensitive with the changes in the temperature.
Theoretical Study of a Novel Four-Chamber Rotary Compressor: Design and Thermodynamic Analysis
Authors: Alduqri Y.A. , Musa Md Nor
Published: January 2016

A novel four-chamber rotary compressor (FCRC) is being developed for a refrigerator and an air-conditioning system. The novelty lies in the usage of three rotating sleeves and two oppositely installed vanes each has one end fixed to an outer sleeve and the other end to a rotor, respectively. In this paper, the swept volume, the delivered pressure, the work and the power of the FCRC are formulated and analyzed. The compressor configuration and thermodynamic analysis are based on the 174 cc swept volume with R134a as the compressed gas. Considering the encouraging results, added by design simplicity of mainly cylindrical shaped components, the proposed FCRC is reckoned to be very suitable to be used for air-conditioning and refrigeration applications.
Electrical Generation Using Renewable Technology for Remote Area: A Review
Authors: Behrouzi Fatemeh , Malik Adi Maimun Abdul , Ahmed Yasser Mohammed , Nakisa Mehdi
Published: January 2016

This paper is a review about process, progress and operation principle of renewable technology using water current as a clean, green and renewable energy to generate electricity for areas especially remote site that access to water but they are poor in electricity.
Modeling of an Optimized Hybrid Energy System for Kutubdia Island, Bangladesh
Authors: Salehin Sayedus , Ehsan M. Monjurul , Noor Shafi , Sadrul Islam A.K.M.
Published: January 2016

This paper presents an optimized energy system model for a small locality in Kutubdia Island, Bangladesh at latitude of 21.82 °N, longitude of 91.86 °E. This isolated island is located at the southern coast of Bangladesh, separated from the main land by the Kutubdia channel. At present, grid connection from the mainland is not present and is not planned in the near future. The proposed energy system comprises Solar PV, Wind turbines, Biogas generators for power generation whereas a diesel generator has been used as backup power supply and batteries have been considered to facilitate energy storage. Hybrid Optimization Model for Electric Renewable (HOMER) has been used to obtain an optimized system comprising all the renewable energy resources present. The designed energy system consists of 28 kW Solar PV panels, 30 kW Wind Turbines, 8 kW Biogas Generator, 9 kW Diesel Generator. The system generates electricity with a renewable fraction of 97%. The cost of electricity has been estimated as US$ 0.42/kWh considering 10% Rate of Return with an initial capital cost of US$ 199,541.
The Road Particle Effect on Squeal Noise of Disc Braking System
Authors: Abdul Rahman Muhammad Arsyad , Hamid Mohd Kameil Abdul , Mat Lazim Ahmad Razimi
Published: January 2016

This experimental work was carried out to examine the effect of road particle on squeal noise exerted at different load and sliding speed. The test was performed under dry sliding condition by utilizing brake test rig and commercial brake pad and discs. Squeal measurement was taken based on frequency, sound pressure level (SPL) value, vibration and brake torque measurement. The output signal from microphone and accelerometer was processed by Fast Fourier Transform analyzer to synchronize value SPL and vibration in the power spectrum graph. Simultaneous increase at the same value of frequency and SPL values showed the squeal occurrence for value above 70dBa and 1000Hz respectively. Result for test with road particle showed number of squeal tends to increase compared to test without road particle. SPL also showed high pitch of noise on squeal with road particle presence. Brake torque significantly increased with increasing brake line pressure and exaggerated with road particle. Higher brake torque resulted in higher coefficient of friction and showed high squeal generation.
Elemental Diffusion Behaviour of Biomedical Grade Titanium Alloy through Thermal Oxidation
Authors: Anwar Mahmood , Izman Sudin , Abdul-Kadir Mohammed Rafiq , Nazim Engku Mohammad , Kadir Aini Abdul , Konneh Mohamed , Ayu Hassan Mas
Published: January 2016

Major issues related to implant failure are wear debris and metal ions release where Titanium-Aluminium-Niobium alloys still face those problems despite of better biocompatibility. Surface modification is one of the alternatives in order to reduce those wear as well as ion release problems to the host tissue. In this study, experiments were carried out to investigate the element diffusion behaviour of Ti-6Al-7Nb alloy through thermal oxidation in order to obtain coating on the surfaces for diminishing those effects. Thermal oxidation was carried out at 650°C for three different durations 6, 12 and 24 hours. It is found that at prolong time, Niobium diffusion occurs where short duration Aluminium dominates. This suggests that longer heating time promotes heavy metal diffusion by restricting diffusion of light metal and hence, dominates the heavy metal oxide layer formation. The oxide layer formed on the substrate may lead to increase the lifespan of the implant and reduces the harmful effects caused by wear debris or toxic ion from metal alloys.
Characteristic of Oil Palm Activated Carbon Produced from Microwave and Conventional Heating
Authors: Zaharah Abas Fatimatul , Ani Farid Nasir
Published: January 2016

Malaysia has been acknowledged as one of the largest producer and exporter in the production of oil palm biomass. This is not surprisingly that industry contributes massive amount of the waste such as empty fruit bunches, palm mesocarpfibre, and palm kernel shell. This abundance of oil palm by-products make them an attractive source of raw material for the production of activated carbon. The activated carbon has been widely used in variety industries such as bio-catalyst, removal of toxic substance, purification of liquid and gas as well as catalyst support. The comparison of characteristic of oil palm activated carbon produced via microwave and conventional heating has been discussed in this paper. The characterization of the activated carbon includes elemental analysis, the Brunauer-Emmet-Teller (BET) surface area as well as Scanning Electron Microscopy (SEM) has been analyzed in this study.Hence, from the result, it shows that the SEM micrograph of oil palm shell (OPS) activated carbon prepared via microwave heating by using chemical activation produced the clearly and uniformly pore compared to full cavity and not well formed of pore in oil palm shell (OPS) activated carbon via conventional heating.
Influence of Some Parameters on Thermo-Hydrodynamic Fluid Flow Behaviour of Solar Chimney Power Plants
Authors: Chergui Toufik , Larbi Salah , Bouhdjar Amor
Published: January 2016

The purpose of this study is related to a numerical simulation of flows in a solar chimney. The mathematical modelling approach used is based on flows in an opened enclosure with two components: a cylinder and a disc. This analysis consists in developing a computer software with dimensionless variables, and in generalized coordinates, in order to simulate an air flow in a chimney, by taking into account different flow regimes. Thermo-hydrodynamic aspect of flows is also analysed by solving the governing equations numerically using the finite volume method with adequate boundary conditions. The results presented are related to air flow velocity and temperature distributions versus Rayleigh number and some geometrical and physical parameters, such as the height of the chimney and the solar radiation intensity. The approach undertaken in this paper is related mainly in analyzing a solar chimney power plant to produce a power of a few MW.
X-Ray Diffraction, Microstructure and Mössbauer Studies of Nanostructured Fe90Mg10  Powders Elaborated by Mechanical Alloying
Authors: El Mohri Abdennour , Guittoum Abderrahim , Taibi K. , Azzaz M.
Published: January 2016

The mechanical alloying (MA) of elemental powder mixtures of Fe90Mg10 (atomic ratio of 79.67:20.33) was performed in an argon atmosphere using a planetary ball mill process. The alloy formation and the different physical properties were investigated as a function of milling time, t (in the 0–54h range) by means of the X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), and Mössbauer spectroscopy (MS). The formation of the solid solution α-Fe (Mg) started after 4 h of milling. The Mg peaks are completely missing. XRD results also indicated that when the milling time increases, the lattice parameter increases, whereas the grain size decreases and the mean level of microstrains increase. The powder particle morphology was observed by SEM at different stages of milling. The Mössbauer spectra were fitted with two sextets corresponding to the crystalline body centered cubic (bcc) Fe phase and a second sextet which represents supersaturated solid solutions of Mg in (α-Fe). The appearance and the increase in intensity of the second sextet 17, 66 % at (12 h) to 50 % (54 h) with t corresponding to the dissolved Mg in the (α-Fe). This may indicate that the interfacial region effect increases with milling time due to the grain size reduction and to the disordered state of the interfacial region.
Effect of Zinc Oxide Nanoparticle Sizes on Viscosity of Nanofluid for Application in Enhanced Oil Recovery
Authors: Lee Kean Chuan , bin Saipolbahri Zulhilmi Akmal , Soleimani Hassan , Zaid Hasnah Mohd. , Guan Beh Hoe , Chuan Ching Dennis Ling
Published: January 2016

Zinc oxide (ZnO) with different nanoparticle (NP) sizes was prepared and synthesized by using the sol-gel method with organic precursor, followed by the characterization of the ZnO nanoparticle by using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) to identify the effect of nanoparticle sizes of ZnO on the viscosity of the nanofluid. The impact of nanoparticle sizes on EOR was investigated. Results showed both viscosity and interfacial tension (IFT) increased with the nanoparticle size.
Microwave Conductivity of Fe and Mg Based Nanocomposites
Authors: Otmane Fadhéla , Triaa S. , Azzaz Mohammed
Published: January 2016

In the present study we report on the microwave conductivity of Fe and Mg based nanocomposites. They consist of an epoxy resin matrix reinforced with coarse Fe, mechanically milled Fe and mechanically milled Mg powders. Mechanically milled powders were obtained by high energy ball milling. The morphology of the obtained powders was characterized using Scanning Electron Microscopy (SEM). Electromagnetic scattering parameters were measured within a rectangular X-band metallic wave guide. Electromagnetic parameters were calculated using the Nicolson-Ross-Weir (NRW) algorithm. Microwave conductivity and associated skin depth spectra of the nanocomposites under study are deduced.
Separation of Sulphuric Acid from an Acid Suspension of Cellulose Nanocrystals by Manual Shaking
Authors: Liew Soon Yee , Thielemans Wim , Hewakandamby Buddhika
Published: January 2016

In this paper, the separation of sulphuric acid from a suspension of cellulose nanocrystal by manual shaking is described. Cellulose nanocrystals are prepared from acid hydrolysis of cotton using 64 wt% sulphuric acid at ca. 45 °C for 45 minutes. After the hydrolysis was complete, water was added to dilute the mixture to a resulting concentration of 30 wt% of the acid. This mixture was shaken rigorously in a closed container and after 48 hours, separation occurs such that cellulose nanocrystals float, with the bubbles introduced by the shaking, to give clear acid solution at the bottom. This shaking-floating process is repeatable for several cycles after the acid was removed from the bottom and more water was added. Using this simple process, the total acid recovery of > 90% has been achieved, and the concentration of all the acid recovered combined was 17.5 wt%. This work demonstrates a method that allows energy efficient and up-scalable separation of cellulose nanocrystals from the acidic suspension from which it was extracted.
Spectral triples and Toeplitz operators
Authors: Engliš Miroslav , Falk Kévin , Iochum Bruno
Published: January 2016

We give examples of spectral triples, in the sense of A. Connes, constructed using the algebra of Toeplitz operators on smoothly bounded strictly pseudoconvex domains in

\mathbb C^n

, or the star product for the Berezin–Toeplitz quantization. Our main tool is the theory of generalized Toeplitz operators on the boundary of such domains, due to Boutet de Monvel and Guillemin.
The Gysin sequence for quantum lens spaces
Authors: Arici Francesca , Brain Simon , Landi Giovanni
Published: January 2016

We define quantum lens spaces as ‘direct sums of line bundles’ and exhibit them as ‘total spaces’ of certain principal bundles over quantum projective spaces. For each of these quantum lens spaces we construct an analogue of the classical Gysin sequence in K-theory. We use the sequence to compute the K-theory of the quantum lens spaces, in particular to give explicit geometric representatives of their K-theory classes. These representatives are interpreted as ‘line bundles’ over quantum lens spaces and generically define ‘torsion classes’. We work out explicit examples of these classes.
A Dixmier–Douady theory for strongly self-absorbing $C^\ast$-algebras II: the Brauer group
Authors: Dadarlat Marius , Pennig Ulrich
Published: January 2016

We have previously shown that the isomorphism classes of orientable locally trivial fields of

C^\ast

-algebras over a compact metrizable space

X

with fiber

D \otimes \mathbb K

, where

D

is a strongly self-absorbing

C^\ast

-algebra, form an abelian group under the operation of tensor product. Moreover this group is isomorphic to the first group

\bar{E}^1_D (X)

of the (reduced) generalized cohomology theory associated to the unit spectrum of topological K-theory with coefficients in

D

. Here we show that all the torsion elements of the group

\bar{E}^1_D(X)

arise from locally trivial fields with fiber

D \otimes M_n (\mathbb C)

,

n\geq 1

, for all known examples of strongly self-absorbing

C^\ast

-algebras}

D

. Moreover the Brauer group generated by locally trivial fields with fiber

{D\otimes M_n (\mathbb C)}

,

n\geq 1

is isomorphic to

T or {\bar{E}^1_D(X)}

.
Action de Hopf sur les opérateurs de Hecke modulaires tordus
Authors: Banerjee Abhishek
Published: January 2016

Let

\Gamma \subseteq SL_2(\mathbb Z)

be a principal congruence subgroup. For each

\sigma \in SL_2(\mathbb Z)

, we introduce the collection

\mathcal A_\sigma (\Gamma)

of modular Hecke operators twisted by

\sigma

. Then,

\mathcal A_\sigma(\Gamma)

is a right

\mathcal A (\Gamma)

-module, where

\mathcal A (\Gamma)

is the modular Hecke algebra introduced by Connes and Moscovici. Using the action of a Hopf algebra

\mathfrak{h}_0

on

\mathcal A_\sigma (\Gamma)

, we define reduced Rankin–Cohen brackets on

\mathcal A_\sigma (\Gamma)

. Moreover

\mathcal A_\sigma (\Gamma)

carries an action of

\mathcal H_1

, where

\mathcal H_1

is the Hopf algebra of foliations of codimension 1. Finally, we consider operators between the levels

\mathcal A_\sigma (\Gamma)

,

{\sigma\in SL_2(\mathbb Z)}

. We show that the action of these operators can be expressed in terms of a Hopf algebra

\mathfrak{h}_{\mathbb Z}

.
Compact quantum metric spaces from quantum groups of rapid decay
Authors: Bhowmick Jyotishman , Voigt Christian , Zacharias Joachim
Published: January 2016

We present a modified version of the definition of property RD for discrete quantum groups given by Vergnioux in order to accommodate examples of non-unimodular quantum groups. Moreover we extend the construction of spectral triples associated to discrete groups with length functions, originally due to Connes, to the setting of quantum groups. For quantum groups of rapid decay we study the resulting spectral triples from the point of view of compact quantum metric spaces in the sense of Rieffel.
Easy quantum groups and quantum subgroups of a semi-direct product quantum group
Authors: Raum Sven , Weber Moritz
Published: January 2016

We consider homogeneous compact matrix quantum groups whose fundamental corepresentation matrix has entries which are partial symmetries with central support.We show that such quantum groups have a simple presentation as semi-direct product quantum groups of a group dual quantum group by an action of a permutation group. This general result allows us to completely classify easy quantum groups with the above property by certain reflection groups.We give four applications of our result. First, there are uncountably many easy quantum groups. Second, there are non-easy homogeneous hyperoctahedral quantum groups. Third, we study operator algebraic properties of the hyperoctahedral series. Finally, we prove a generalised de Finetti theorem for those easy quantum groups in the scope of this article.
Jacobi and Poisson algebras
Authors: Agore Ana L. , Militaru Gigel
Published: January 2016

Jacobi/Poisson algebras are algebraic counterparts of Jacobi/Poisson manifolds. We introduce representations of a Jacobi algebra

A

and Frobenius Jacobi algebras as symmetric objects in the category. A characterization theorem for Frobenius Jacobi algebras is given in terms of integrals on Jacobi algebras. For a vector space

V

a non-abelian cohomological type object

{\mathcal J}{\mathcal H}^{2} \, (V, \ A)

is constructed: it classifies all Jacobi algebras containing

A

as a sub algebra of codimension equal to

{\rm dim} (V)

. Representations of

A

are used in order to give the decomposition of

{\mathcal J}{\mathcal H}^{2} \, (V, \ A)

as a coproduct over all Jacobi

A

-module structures on

V

. The bicrossed product

P \bowtie Q

of two Poisson algebras recently introduced by Ni and Bai appears as a special case of our construction. A new type of deformations of a given Poisson algebra

Q

is introduced and a cohomological type object

\mathcal{H}\mathcal{A}^{2} \bigl(P,\, Q ~|~ (\triangleleft, \, \triangleright, \, \leftharpoonup, \,\rightharpoonup)\bigl)

is explicitly constructed as a classifying set for the bicrossed descent problem for extensions of Poisson algebras. Several examples and applications are provided.
The Rokhlin property vs. Rokhlin dimension 1 on unital Kirchberg algebras
Authors: Barlak Selçuk , Enders Dominic , Matui Hiroki , Szabó Gábor , Winter Wilhelm
Published: January 2016

We investigate outer symmetries on unital Kirchberg algebras with respect to the Rokhlin property and finite Rokhlin dimension. In stark contrast to the restrictiveness of the Rokhlin property, every such action has Rokhlin dimension at most one. A consequence of these observations is a relationship between the nuclear dimension of an

\mathcal O_\infty

-absorbing C*-algebra and its

\mathcal O_2

-stabilization. We also give a more direct and alternative approach to this result. Several applications of this relationship are discussed to cover a fairly large class of

\mathcal O_\infty

-absorbing C*-algebras that turn out to have finite nuclear dimension.
AN INDEX TO SELECTED SCIENTIFIC NAMES IN EDWARDS' (1929) MONOGRAPH ON BRITISH CHIRONOMIDAE
Authors: Spies Martin
Published: January 2016

--
CHIRONOMID FAUNA OF CENTRAL YAKUTIAN LAKES (NORTHERN RUSSIA) IN PALAEOENVIRONMENTAL INVESTIGATION
Authors: Nazarova L , Kumke T. , Pestrjakova L , Hubberten H.-W.
Published: January 2016

--
FOR DIGNITY AND POWER: Black Women’s Political Leadership in Postwar St. Louis
Authors: Ervin Keona K.
Published: January 2016

St. Louis was not only one of the most segregated cities in the twentieth century, but it was also a major hub of organized resistance led especially by Black women. The Gateway City was a crucible for the emergence of Black women’s leadership in the post-World War II period. A mid-sized border city, St. Louis was a point of regional confluence. Its relatively small Black population, rigid lines of racial demarcation in jobs and housing, and the local Black freedom movement that centered on working-class interests all factored into Black women’s formal political leadership of mainstream civil rights institutions in St. Louis, where they held considerable public voice. From the 1940s to early 1980s in St. Louis, Pearl S. Maddox, Marian Oldham, DeVerne Calloway, Jean King, and Ora Lee Malone fought locally to expose and ameliorate the structural causes of racialized poverty. Leading campaigns for jobs, decent working conditions, affordable housing, state-based economic protections, living wages, welfare rights, and unfettered Black access to urban space and the consumer marketplace, women activists were key architects of freedom agendas. They pushed political progress not only in civil rights organizations but also in unions and state government, as they addressed the compounding impact of urban inequality in postwar America.
Noble Metal Nanoparticles and Their (Bio) Conjugates. II. Preparation
Authors: Capek Ignác
Published: January 2016

Hybrid nanoparticles of gold and silver can not only retain the beneficial features of both nanomaterials, but also possess unique advantages (synergism) over the other two types. Novel pseudospherical and anisotropic nanoparticles, bimetallic triangular nanoparticles, and core@shell nanoparticles were prepared by the different procedures for various applications and understanding both the particle evolution (nucleation) and nanoparticle anisotropy. Hybrid nanoparticles of gold and silver are considered to be low in toxicity, and exhibit facile surface functionalization chemistry. Furthermore, their absorption peaks are located in visible and near-infrared region. These nanoparticles provide significant plasmon tunability, chemical and surface modification properties, and significant advances in the growth into anisotropic nanostructures. The photoinduced synthesis can be used to prepare various (sub) nanoparticles and OD and 1D nanoparticles. Ostwald and digestive ripening provided narrower particle size distribution.
Providing Perpetual Access
Authors: Glasser Sarah
Published: January 2016

This paper presents the results of an online survey about perpetual access for electronic serials that have been canceled, have ceased, or have transferred to different publishers. The survey sought to ascertain the true experiences of libraries working to maintain perpetual access. Results indicate a high success rate for providing perpetual access. Results also indicate a lack of standardization for and many challenges to keeping track of and providing perpetual access. A discussion section expands on key findings and the most common obstacles to providing perpetual access.