bluuebunny/crossref_metadata_2025 huggingface dataset:
Past, Future and Presents
Authors: Cook Ruth Gannon , Ley Kathryn
Published: January 2016

This study approaches educational marketing from the perspective of the customers, the students. Instructors and instructional designers have designed online learning using a process that revolves around delivery. The process addresses meeting the needs of administrators and aligns well with the growing demands of the educational marketplace. But the growing failure of students to successfully complete online courses warrants further exploration than simply adding more interactivities or instructor interaction. The authors pose that advertising and marketing have addressed complex consumer relationships for almost a century and have created long term successful customer relationships which could provide insights to help with higher education student retention issues. A look at design development research and marketing semiotics could provide greater understanding and student involvement to help marketing semiotics provide a deeper understanding of the importance of inclusion of students' life experiences and cultural histories.
Indonesian Government Knowledge Management Model
Authors: Sensuse Dana Indra , Wibowo Wahyu Catur , Cahyaningsih Elin
Published: January 2016

Knowledge management is a strategic issue that is usually used for strategic planning of organizational development in order to reach organization competitiveness and retaining organization knowledge. It has also become a trend in Governmental institution for implementing knowledge management align with the regulation. Internal employee rotation, promotion mutation and open bidding program among government institution take part of this loosing knowledge. Knowledge management model is set of knowledge process that encourage knowledge management initiative can enhance organizational objectives. Therefore it is needed to determine the suitable knowledge management model for the government, because the necessity of this model to accomplish some issues above. This research conducted a literature review and previous study analysis to build a theoretical model of Indonesian government knowledge management. Classification, categorization and elaboration analysis are used for construct a new theoretical model. Indonesian knowledge management model consists of two stages defining organizational strategy that delivering organizational strategy and knowledge management strategy stages which is consist of five elements, there are organization culture, critical success factor of knowledge management, SWOT analysis, organization KM process and organization knowledge map.
Modeling and Parametric Study of Cooling Loads Characteristics for Automotive Air-Conditioning System
Authors: Sukri M.F. , Musa Md Nor , Senawi M.Y. , Nasution H.
Published: January 2016

This paper presents a steady-state modeling and parametric study on the characteristics of cooling loads for an automotive air-conditioning system. The model enables the hourly prediction of vehicular cabin cooling load profile at various operating conditions and types of vehicle. The model utilizes correlations and equations proposed by ASHRAE and previous researchers available in the open literature. A validation exercise indicates that the simulation results are within 5% of published results. In the parametric study, the effects of five parameters: vehicle surface color, number of passenger, cabin temperature, vehicle speed and angle of front wind screen on the hourly cooling load profile on a daily basis are investigated. It was found that an increase in number of passenger and vehicle speed, darker vehicle surface color and lower cabin temperature will increase the cooling load. Meanwhile, the angle of front wind screen does not significantly influence the cooling load profile. In conclusion, the cooling loads profile can be used for air-conditioning system improvement/optimization exercise. The generic model can be used for complete vehicle air-conditioning simulation program towards energy-efficient air-conditioning system for better overall performance, especially in the early stage of vehicle development.
Investigation of the PMV and TSV Models of Thermal Comfort in Air-Conditioned University Classrooms in Malaysia
Authors: Shaari Nur Atikah , Zaki Sheikh Ahmad , Mat Ali Mohamed Sukri , Abd Razak Azli
Published: January 2016

A field study was done on the thermal comfort of seven air-conditioned university classrooms in the hot and humid climate of Malaysia. The aims of this paper are to investigate the perceptions of thermal comfort and the adaptation method of students in air-conditioned classrooms. In total, 189 respondents from the classrooms completed the questionnaire. A comparison was made between the Predicted Mean Vote (PMV) and the Thermal Sensation Vote (TSV) and it was found that the TSV values tended to be more sensitive than the PMV values. A variety of adaptation methods of the occupants in the classrooms are also presented. It was found that most of the occupants preferred to change the air-conditioning thermostat, probably because all the occupants had the opportunity to control the thermostat.
Evaluation of the Impacts of Refrigerant Charge of HC-290 to Replace HCFC-22 in a Freezer Performance
Authors: Sutandi Tandi , Sumeru K. , Nasution Henry , Ani Farid Nasir
Published: January 2016

Propane (HC-290) is one of hydrocarbons often called as a green refrigerant. As a result, in the long term, this refrigerant is able to be used as a substitute refrigerant to HCFC-22. Generally, the amount of charging HC-290 to replace HCFC-22 based on the density ratio of the refrigerants, for instance, the ratio of liquid density at-10°C between HCFC-22 and HC-290 is 40.59%. Also, most investigations reported that the refrigeration system performances of HC-290 were better compared to HCFC-22 without varying the refrigerant charging of HC-290. By varying the refrigerant charging of HC-290 in a freezer, the performances can be optimized. This study presents an experimental investigation of the impacts on the performances of a freezer when the refrigerant charging of HC-290 is varied replacing HCFC-22. Three performances are reported in the present study, namely: cooling capacity, input power and COP. The first experiment was performed on a freezer using HCFC-22 as working fluid and the amount of refrigerant charging was 450 gram. Furthermore, the tests were carried out using HC-290 with six charging conditions: viz.: 30, 35, 40, 45, 50 and 55% of the mass of HCFC-22. The results showed that when refrigerant of HC-290 was charged 45% (mass) of HCFC-22, the freezer yielded the biggest increase in the cooling capacity and COP.
Effect of Air to Air Fixed Plate Enthalpy Energy Recovery Heat Exchanger Flow Profile on Air Conditioning System Energy Recovery
Authors: Nasif Mohammad Shakir , Al-Waked Rafat
Published: January 2016

Fixed plate enthalpy heat exchanger which utilizes permeable material as heat and moisture transfer surface has been used as an energy recovery system to recover sensible and latent heat in HVAC systems. The heat exchanger effectiveness is affected by the air flow profile. It is well known that counter flow configuration provides highest effectiveness, however, in real applications, it is not possible to implement a counter flow configuration, as both inlet and outlet ducts of the two flow streams are located on the same side of the heat exchanger. Therefore, several quasi-counter-flow heat exchanger designs including Z-shaped, L-shaped, Z-shaped opposite flow configurations are proposed in this research and their effect on energy consumed by an air conditioning cooling coil has been investigated, where each of the proposed heat exchanger is incorporated in an air conditioning cooling coil model. The modeled cooling coil energy consumption and energy recovered by the heat exchangers are evaluated under Kuala Lumpur weather conditions. It has been found that an air conditioner coupled with L-shaped heat exchanger recorded up to 20% increase in energy recovery in comparison with Z-shaped oposite and Z-shaped heat exchanger.
Numerical Simulation of the Transient Development of Slug Flow in Horizontal Pipes
Authors: Al-Hashimy Zahid Ibrahim , Al-Kayiem Hussain H. , Nasif Mohammad Shakir , Mohmmed Abdalellah. O.
Published: January 2016

Slug flow regime in two and multi-phase flow in pipes is a complicated flow phenomena representing challenge in the design of the piping system. In the present work, water/air two phase flow was modeled and simulated as 3 dimensional, transient, and incompressible flow using Volume of Fluid technique in STAR-CCM+ software. The simulation was conducted to predict and evaluate the air-water slug flow in a horizontal pipe with 0.16 m diameter and 7 m long. The superficial velocities for both phases were extracted from Baker chart slug zone. The results were validated against experimental bench marking referenced in Baker chart and the proposed VOF technique shows a good capability in simulating the development of the slug flow regime. This model could be utilized for simulation of various two phase flow regimes.
Experimental Study of a Laminar Flow Solid Desiccant Dehumidifier Driven by a Low Temperature Heat Source
Authors: Jin Oh Seung , Thu Kyaw , Shahzad Muhammad Wakil , Chun Wongee , Ng Kim Choon
Published: January 2016

In this paper, an experimental study of a laminar flow solid desiccant dehumidifier has been presented. The cyclic steady state performance of adsorption-desorption processes was analyzed at various heat source temperatures and typical ambient humidity conditions in tropics. The desiccant dehumidification system consists of two beds filled with silica gel, two heat exchangers operating at 30 oC and 80 oC respectively, three humidity stations for measurement of the temperature and humidity conditions of the system and a blower to make airflow throughout the system. Type-RD silica gel of 0.3 mm average diameter was used as the working desiccant in the dehumidification system. This system has no moving parts rendering less maintenance compared with a rotary type. It is also energy-efficient means of dehumidification by adsorption process with low temperature heat source as compared to the conventional methods. As a result, it was observed the humidity ratio of inlet air is reduced from 24 g/kg of dry air to about 17 g/kg of dry air. Concomitantly, hot water at 80 oC is used to regenerate the adsorbent.
Numerical Investigation of Turbulent Magnetic Nanofluid Flow inside Straight Channels
Authors: Che Sidik Nor Azwadi , Raad Abdulwahab Mohammed
Published: January 2016

A numerical study using computational fluid dynamics method with an approach of single phase has been presented in order to determine the effects of the concentration of the nanoparticles and flow rate on the convective heat transfer and friction factor in turbulent regime flowing through three different straight channels (straight, circular and triangular) with different Reynolds number (5000 ≤ Re ≤ 20000) using constant applied heat flux. The nanofluid was used consist of Fe3O4 magnetic nanoparticles with average diameter of (13nm) dispersed in water with four volume fraction (0, 0.2, 0.4, 0.6%). The results revealed that as volume fraction and Reynolds number increase Nusselt number increase and the heat transfer rate in circular cross section tube is better than that in square and triangular cross section channels.
Investigation of Inverse-Turbulent-Prandtl Number with Four RNG k-ε Turbulence Models on Compressor Discharge Pipe of Bioenergy Micro Gas Turbine
Authors: Siswantara Ahmad Indra , Budiarso Budiarso , Darmawan Steven
Published: January 2016

Inverse-Turbulent Prandtl number (α) is an important parameter in RNG k-ε turbulence models since it affects the ratio of molecular viscosity and turbulent viscosity. In curved pipe, this highly affects the model prediction to a large range eddy-scale flow. According to Yakhot & Orzag, the α range from 1-1.3929 has not been investigated in detail in curved pipe flow (Yakhot & Orszag, 1986) and specific Re. This paper varied inverse-turbulent Prandtl number α to 1-1.3 in RNG k-ε turbulence model on cylindrical curved pipe in order to obtain the optimum value of α to predict unfully-developed flow in the curve with curve ratio R/D of 1.607. Analysis was conducted numericaly with inlet specified Re of 40900 which was generated from the experiment at α 1, 1.1, 1.2, 1.3. Wall surface roughness is not considered in this paper. With assumption that thermal diffusivity is always dominant to turbulent viscosity, higher Inverse-turbulent Prandtl number represent domination of turbulent viscosity to molecular viscosity of the flow and predict to have more interaction between large scale eddy to small scale eddy as well. The results show the use of α = 1.3 has increased the turbulent kinetic energy by 7% and the turbulent dissipation by 5% compared to general inverse-turbulent Prandtl number of 1. The value difference shows that the use of higher α on RNG turbulence model described more interaction between eddies in secondary and swirling flow at pipe curve at Re = 40900.
Hydrodynamic Design of New Type of Artificial Reefs
Authors: Yaakob Omar B. , Ahmed Yasser M. , Jalal M. Rajali , Faizul A.A. , Koh Koh K. , Zaid Tarmizi J.
Published: January 2016

The purpose of this research work is to study the hydrodynamic characteristics of a new type of artificial reef structure, in order to provide a structure with low flow resistance, which will be a more suitable shelter for fishes and marine organisms. The idea of the new artificial reef is based on the streamlined bicycle helmet design concept. The hydrodynamic characteristics of the helmet and hollow cube artificial reefs (ARs) of the same volume have been studied at different water depths and wave frequencies of Malaysia seas using Computational Fluid Dynamics (CFD) method. The finite volume RANSE (Reynolds-Averaged Navier-Stokes Eqs.) code Ansys CFX was used for calculating the reefs drag force (FD) and flow characteristics, while the potential flow code Ansys Aqwa was used for calculating the reefs inertia force (FI). The Shear Stress Transport (SST) turbulence model was used in the RANSE code. The results of the two ARs were then compared for studying the hydrodynamic improvement due to the use of streamlined helmet artificial reef on the flow pattern around it. The streamlined body of the helmet artificial reef enhances the flow pattern at the aft region of the reef and provides flow zones with moderate flow speed at this area, which can help fishes and marine organisms from finding good shelter. The special shape of the different openings in the body of the helmet artificial reef improves the condition of the flow velocity distribution inside the unit than that of the hollow cube unit, which can increase the amount of the nutrient to the living fishes and organisms inside the reef.
Cost Estimation Study for the Effect of Biofouling on Engine Cooling System Performance with an 8000 BHP Vessel
Authors: Pamitran Agus Sunjarianto , Adam Samuel Agustinus , Nasruddin Nasruddin , Alhamid Muhammad Idrus
Published: January 2016

Every engine needs a cooling system in order to maintain the performance of engine. In this study the cooling system is applied in naval ship with the exchange of freshwater and seawater. Since the seawater contains biological fouling, then it is scaled in the heat exchanger so that the performance of heat exchanger is decreasing from time to time. This makes the heat transfer rate in cooler is less efficient so that to maintain the BHP of the engine it needs to consume more fuel. The result shows that the effect could incur a loss of about USD 463,852.8/month. This condition makes the importance of cooling system maintenance in order to keep the temperature of the naval ship engine and to minimize the additional fuel cost. For cooling system itself, to keep the cooler in a good condition, it needs to clean the cooler for every 720 hours, or once a month.
Initial Study on Hydrogen Permeation with Flat Sheet Pd/Ag Membrane for Mixture of Hydrogen and Carbon Dioxide
Authors: Faizal Hasan Mohd , Kawasaki Yuki , Yokomori Takeshi , Ueda Toshihisa
Published: January 2016

The hydrogen permeation with a flat sheet Pd/Ag membrane for mixture of hydrogen and carbon dioxide was investigated experimentally. A flat sheet, dense 77wt.%Pd/23wt.%Ag purification membrane with thickness of 25μm and diameter of 0.02m was used. The membrane temperature, total upstream pressure and inlet H2 mole fraction were set to 623K, 0.25MPa and 0.75, respectively. Meanwhile, the downstream pressure was set at atmospheric. Mean mole flux (feed flow rate/effective membrane surface area) was varied between 0.089-0.62mol.s-1.m-2. When the mean mole flux is increased, hydrogen permeation flux increases, which is supposed due to the effect of flow velocity. In addition, the analytical result based on Sieverts’ equation with the effect of permeation is found to be very close with the experimentally obtained hydrogen permeation flux. For permeation with H2:CO2 mixture, future work is necessary to investigate the variation in permeation flux with time.
Exergy Analysis and Exergoeconomic Optimization with Multiobjective Method of Unit 4 Kamojang Geothermal Power Plant
Authors: Nasruddin Nasruddin , Masdi Septian Khairul , Surachman Arief
Published: January 2016

This study presents four analysis at unit 4 Kamojang geothermal power plant are exergy analysis at current condition, exergy efficiency optimization, economic optimization, and exergoeconomic optimization with wellhead valve pressure as a variable. Calculations are conducted by using the MATLAB. Thermodynamics characteristic of geothermal fluid assumed as water characteristic which get from REFPROP. Wellhead pressure operational condition 10 bar has exergy efficiency 31.91%. Exergy efficiency optimization has wellhead valve pressure 5.06 bar, exergy efficiency 47.3%, and system cost US$ 3,957,100. Economic optimization has well pressure 11 bar, exergy efficiency 22.13%, and system cost US$ 2,242,200. Exergoeconomic optimization has 15 optimum condition. Exergoeconomic optimization aims to analyze the optimum wellhead valve pressure for maximum exergy efficiency and minimum cost of power plant system.
Prediction of Gas Hydrate Formation Using Radial Basis Function Network and Support Vector Machines
Authors: Ibrahim A.A. , Lemma T.A. , Kean Moey Lip , Zewge Mesfin Gizaw
Published: January 2016

The oil and gas industry struggles to prevent formation of hydrates in pipeline by spending substantial amount of dollars. Hydrates are ice-like crystalline compounds that are composed of water and gas in which the gas molecules are trapped in water cavities. The hydrate formation is favorable at elevated pressure and reduced temperature and can be determined through experiment. However, the cost involved to determine early hydrate formation using experiment is driving researchers to seek for robust prediction methods using statistical and analytical methods. Main aim of the present study is to investigate applicability of radial basis function networks and support vector machines to hydrate formation conditions prediction. The data needed for modeling was taken from well-established literature. Performance of the models was assessed based on MSE, MAE, MAPE, MSPE, and Modified Pearson’s Correlation Coefficient. Data-based models enable the oil industry to predict the conditions leading to hydrate formation hence preventing clogging of the pipeline and high pressure buildup that could lead to sudden burst at the connections.
Thermo-Mechanical Investigation of Free Volume Theory for Polyamie-6
Authors: Umer Jamal , Saprounov Ivan , Emri Igor , Zupančič Barbara , Shahzad Muhammad Wakil
Published: January 2016

Polymers always show time-dependent mechanical properties. In order to use polymers in engineering applications, long-term mechanical propertes should be characterized. Free volume theroy is the mostly used theory to predict and model the mechanical properties of polymers. The effect of temperature is modelled thorugh William-Landel-Ferry (WLF) equation, whereas, the combined effect of temperature and pressure is modelled by Filler-Moonan-Tschoegl (FMT) equation. Both of the models are based on free volume theory. A set of expermentations were performed to investigate the validity of free volume concpet for one of the most important engineering polymer; i.e. Polyamide-6.
Thermal Conductivity for Mixture of Rice Husk Fiber and Gypsum
Authors: Musa Mohamad Nor , Abdul Aziz Mohamed Fikhri
Published: January 2016

This project is conducted with aim to determine the thermal conductivity for mixture of rice husk fiber and gypsum. The thermal conductivity value for 100% gypsum is also determined in this project for comparison purpose. The experiment used the Guarded Hot Plate Method, single specimen apparatus. This method is based on one-dimensional heat flow through conduction and steady state technique. Four samples have been tested which are 100% gypsum with a mass of 1kg for sample 1, a mixture of 0.1kg of rice husk fiber and 1kg gypsum for sample 2, mixture of 0.2kg of rice husk fiber and 1kg gypsum for sample 3 and a mixture of 0.3kg of rice husk fiber and 1kg gypsum for sample 4. From the data of the experiment that have been carried out, the value of thermal conductivity is decreasing with the increasing of rice husk fiber in the sample. The value of thermal conductivity is 0.772W/mK for sample 1, 0.7574 W/mK for sample 2, 0.7469W/mK for sample 3 and 0.7368W/mK for sample 4. The rice husk fiber is a bio-waste material and the mixture of rice husk fiber and gypsum will add value to the material as gypsum are widely used in construction field such as for plaster ingredient and ceiling finishing because it is a good insulator. The mixture of rice husk fiber and gypsum improve the 100% gypsum thermal conductivity and therefore the mixing of these two materials should have bright application potential.
Strategy for Cooling Green Buildings
Authors: Bielek Boris
Published: January 2016

Green building and its strategic areas for conservation or the rational use of material, energy and water resources. Fundamentals of cooling and basic strategies for cooling green building. Wide range of passive forms of building cooling based on the utilization of natural physical phenomena and renewable energy. Cooling by cross-ventilation. Cooling by stack ventilation. Earth tube cooling. Cooling by earth sheltering. Cooling by night ventilation with thermal mass. Cooling by sun shading system. Cooling through physical cavity of building. Cooling the building with energy from renewable sources – solar cooling systems, heat pumps using the energy of natural environment, well water direct cooling systems.
Sustainability of ETICS Maintenance Technologies
Authors: Minarovičová Katarína , Antošová Naďa
Published: January 2016

A strategy for the recovery of the building stock in Slovakia imposes obligations and proposals to provide additional investment for renovation with a view to 2020, aiming at further reduction of energy consumption of buildings and reducing the consumption of natural fuel resources. Maintenance of existing External Thermal Insulation Composite Systems (ETICS) remains without system solutions, using chemical methods for disposal of microorganisms. Environmental impacts at a price of current sociological needs are not known and detected. Principles of sustainability must be regarded as the starting point when applying the concept of ETICS maintenance.
Development of Boundary Layer in CRIACIV in Florence (Prato) and Comparison with CFD
Authors: Magát Marek , Olekšáková Ivana , Žilinský Juraj
Published: January 2016

In this article are described the results from testing profile of atmospheric boundary layer in BLWT (Boundary layer wind tunnel) in Florence (Prato), Italy with emphasis on comparison of the results with simulations in CFD (Computational fluid dynamics) software OpenFoam. The values are compared with calculated values from EuroCode.
Comparison of Pressure Coefficients of Cube Silsoe with the Results in the Wind Tunnel of Faculty of Civil Engineering in Bratislava
Authors: Lobotka Peter , Žilinský Juraj
Published: January 2016

At the small town of Silsoe, UK , under the leadership of engineer Richards the model was made up with edge of the cube 6 m, used for research of wind on the model. Cube named Silsoe took over many laboratories in the world and diminished cube was tested in the wind tunnel. The aim of our study was to compare recently built the wind tunnel Faculty of Civil Engineering in Bratislava with other sites in the world. Suitable for this purpose served just cube model Silsoe of the edge of 200 mm, which was tested in the wind tunnel of Faculty of Civil Engineering and subsequently also in the workplace at VZLU Prague. The model coefficients were measured the pressure on the cladding of cube and compared with the other measurements. The test results are presented in this paper.
Comparison of Requirements in Slovak and Selected Foreign Legislation on the Issue of Safe Distance of the Wooden Building Structures from the Flue
Authors: Lišková Zuzana , Olbřímek Juraj
Published: January 2016

The paper deals with the solution of interconnections of flue and combustible construction products in the fire safety design. It is focused mainly on a prescribed value of safe distance of the wooden building construction from a single-walled metal chimneys. The aim of article is to point out the necessity to solve the contradictory requirements in the Slovak legislation and inconsistency with the foreign regulations in terms of fire rates caused by chimneys and flues.
Daylighting for Buildings: Influence of the Solar Eclipse on its Spectral Characteristics
Authors: Hartman Peter , Hanuliak Peter , Fabian Miroslav , Darula Stanislav
Published: January 2016

Extraordinary occurrence of the solar eclipse offers opportunity to evaluate spectral characteristic changes and intensities of daylighting during its various phases. Changes of the daylight spectrum in positions: zenith and 45° above horizon with orientation of sensors opposite to sun position were measured. Changes of horizontal illuminance and luminance as well as changes of the correlated colour temperature in the range of the Planck curve were measured in Bratislava and evaluated. Paper presents results of experimental measurements and discusses in point of view of sunlight characteristic’s changes as source of daylighting.
Solution of Own Window Pane Oscillation by Subspace Iteration Method
Authors: Bagoňa Miloslav , Šimiček Jozef , Baláž Richard
Published: January 2016

Solving building acoustic of structures leads to a requirement to know behavior of dynamically loaded structures. Often used design is a window, that glass pane can be modeled as board. When measuring acoustic qualities of windows, monitored value is frequency of excited sound as a sound pressure. From solutions of dynamically loaded structures is known fact that when excited frequency of load is equal, or approximately equal to its natural frequency, there is an unwanted resonance phenomenon.
The Results of Experimental Measurements of the Effects of Floating Floor Washers
Authors: Dlhý Dušan , Tomašovič Peter , Petrák Peter
Published: January 2016

Many manufacturers of spring washers laid under floating floors express the effect of the reduction in a normalized impact noise level as a single digit number ∆L(dB) without defining the composition of the ceiling construction and wear layer, where the reduction in impact noise has occurred. This expression represents the quality and efficiency of washers for general public as well as for experts (architects, designers), which however, cannot be achieved by in situ (on site) measurements.
Requirements and Solution of Barrier-Free Measures upon Architectonic – Construction Solution of Kitchen and Bathroom in a Flat of Special Determination
Authors: Pernišová Alena
Published: January 2016

Healthy person does not often realize its certainty when he moves around in the flat and makes activities related to running of the household. Persons on wheelchairs, moving with crooks or walking stick, or otherwise handicapped, are in more difficult situation. Therefore barrier-free environment in flats defined for persons with limited ability of movement and orientation is very important. This group of people faces the biggest problem with barrier-free transfer when working in the kitchen, as well as when moving around in the bathroom or WC. In order to better understand the wheelchair person we have to take into consideration how this person moves around in the kitchen, how he gets from and on the wheelchair in the bathroom and WC. He movers either alone or with his assistant, therefore the project engineer shall also consider the handling space for another person when designing the size of floor area. Persons with handicap must deal with safe movement around their flat on everyday basis.
Adaptation of the Ruin of Outbuilding next to Classicist Manor-House in Opatová - Lučenec
Authors: Varga Tibor , Pauliny Pavol , Ingeli Rastislav
Published: January 2016

Is it possible to live in a ruin while meeting the contemporary construction and engineering requirements for the interior and preserving its authenticity at the same time? The ruin of outbuilding is located in a protected area of the classicist manor-house from the second half of the 19th century. In order to sustain the continuity of the character of such historical environment, the goal was to preserve its appearance as much as possible. The proposed adaptation of the outbuilding ruin for residential usage applies an experimental concept of reconstruction using progressive and renewable building materials and technological procedures. In this contribution, we deal with the designed reconstruction of the building while preserving authenticity and considering the energy requirements applicable in our legislation. Under the current marginal conditions, it is not only the energy needs for the heating season that need to be solved. The project shall be considered comprehensively, i.e. including the energy needed for cooling. The submitted building concept calculates with energy for both the heating and cooling season. The question is whether or not it is possible to design the NZEB concept for the reconstructed building observing the contemporary construction and engineering requirements for the interior while preserving its authenticity?
The Effect of Process Parameters on the Mechanical Properties of A356 Al-Alloy/ZrO2 Nanocomposite
Authors: Shash Ahmed Y. , Amer Amer E. , El-Mahallawi Iman , El-Saeed Moataz A.
Published: January 2016

In this study the effect of zirconia (ZrO2) nanoparticles (40 nm) in reinforcing A356 aluminum alloys as a base metal matrix were investigated. Zirconia nanopowders were stirred in the A356 matrix with different fraction ratios ranging from (0, 1, 2, 3, 5%) by weight at variable stirring speeds ranging from (270, 800, 1500, 2150 r.p.m) at a mushy zone (600°C) and liquid state (700°C) using a constant stirring time for one minute. The microstructure revealed the change of grains from dendritic to spherical shape with increasing stirring speed. The Scanning Electron Microscopy of the fractured surface revealed the presence of nanoparticles at the interdendritic spacing of the fracture surface and was confirmed with EDX analysis of these particles.The results of the study showed that the mechanical properties (strength, elongation and hardness) using ZrO2 as reinforcements were increased at the following parameters: 1500 r.p.m stirring speed in semi-solid state (600oC) and adding 3 wt.% of ZrO2.
On the Modeling of Eigenmodes and Eigenfrequencies of Carbon Graphene Sheets under the Influence of Vacancy Defects
Authors: Kazemi Seyedeh Alieh , Yengejeh Sadegh Imani , Öchsner Andreas
Published: January 2016

The vibrational behavior of defected graphene sheets was investigated via finite element analysis. The simulations were carried out for perfect and imperfect nanosheets. This study was conducted to examine the influence of vacant sites on these nanostructures. In the current study, a graphene sheet is considered as a space frame. The natural frequency and corresponding mode shapes of the perfect and defective nanosheets were obtained and compared. Results are presented as diagrams stating the natural frequency of graphene sheets with respect to the amount of vacancy defects. The results indicate that the natural frequency of nanosheets reduced by introducing atomic defects to the configuration of these nanomaterials. Such impurities lower the vibrational stability of graphene sheets.
Optimization of High Energy Ball Milling Parameters for Synthesis of Ti1-xAlxN Powder
Authors: Radune Maya , Zinigrad Michael , Frage Nachum
Published: January 2016

Taguchi’s method was applied to investigate the effect of the main HEBM parameters: milling time (MT), ball to powder weight ratio (BPWR) and milling speed (MS) on the dissolved AlN fraction in TiN. The settings of HEBM parameters were determined by using the orthogonal experiments array (OA). The as-received and milled powders were characterized by X-ray diffraction (XRD). The optimum milling parameter combination was determined by using the analysis of signal-to-noise (S/N) ratio. According to the analysis of variance (ANOVA) the milling speed is the most effective parameter and the optimal conditions for powder synthesis are: MT 20h, MS 600rpm, BPWR 50:1. The result of the experiment conducted under optimal conditions (AlN was completely dissolved during experiment) confirmed the conclusions of the statistical analysis.
Use of Pseudoboehmite Nanoparticles for Drug Delivery System of Glucantime®
Authors: Munhoz Jr. Antônio Hortêncio , Martins J.S. , Ribeiro Roberto R. , Miranda Leila Figueiredo , Andrades R.C. , Bertachini K.C. , Silva L.G.A.
Published: January 2016

Recently, the incidence of American Cutaneous Leishmaniasis (ACL) has been grown in Latin America, especially in Brazil, where from 1980 to 2005, 605,062 cases were recorded. The drug glucantime®, whose active principle is the meglumine antimoniate (or meglumine antimonate) is used in the treatment of leishmaniasis. Its toxicity is due mainly to the presence of antimony in its structure. Therefore, it is crucial to determine the safe dose levels of this drug in the treatment. Drug delivery systems have been currently the focus of many studies due to its effectiveness in treating diseases proved to be superior compared to conventional methods. Drug delivery systems can avoid overdosing by decreasing the amount of drug intake, which results in a better therapeutic effect in addition to reducing the risks of plasma concentration reaching toxic levels. Synthetic nanomaterials have been receiving great attention due to their potential applications in pharmaceutical technology as well as the possibility of controlling their particle size and composition, which allows a better performance in drug release. Pseudoboehmite is a synthetic aluminum compound precursor of alumina [1] and a polymorph of boehmite, with active groups in its structure [2], making it an excellent adsorbent material. In this work, pseudoboehmite was prepared by using the sol-gel process for being used as an excipient. The incorporation of pseudoboehmite in glucantime® was performed in the processing of tablets. Both pseudoboehmite and the tablets were characterized via X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TG), and scanning electron microscopy (SEM) using secondary electron detector and EDS detector. The release profile was obtained by UV/Vis spectroscopy for in vitro simulation. No reaction between the drug and the excipient was observed.
Numerical Simulation of the Mechanical Behaviour of Single-Walled Carbon Nanotube Heterojunctions
Authors: Sakharova Nataliya A. , Pereira André , Antunes Jorge M. , Fernandes José Valdemar
Published: January 2016

The study of the mechanical behaviour of single-walled carbon nanotube heterojunctions has been carried out, implementing nanoscale continuum approach. A three-dimensional finite element model is used in order to evaluate the elastic behaviour of cone heterojunctions. It is shown that the bending rigidity of heterojunctions is sensitive to bending conditions. The torsional rigidity does not depend on torsion conditions. Both rigidities of the heterojunction are compared with those of the thinner and thicker constituent nanotubes.
Two-Dimensional Observation of the Core–Mantle Model for Superplastic Flow in an ODS Ferritic Steel
Authors: Masuda Hiroshi , Tobe Hirobumi , Sato Eiichi , Sugino Yoshito , Ukai Shigeharu
Published: January 2016

Two-dimensional grain movements were microscopically observed in high-temperature shear deformation of an oxide-dispersion-strengthened ferritic steel with an elongated and aligned grain structure that was sheared in a direction perpendicular to the grain long axis. The microstructure was analyzed using electron back-scattered diffraction and electron channeling contrast imaging techniques before and after the shear deformation. Clear grain switching events, which are assumed to occur via grain-boundary sliding (GBS), were observed and the switching mechanism was characteristic of the core–mantle superplasticity model proposed by Gifkins; dislocation densities got much higher in narrow areas near the grain boundaries (mantles) than the grain interiors (cores). The mantle regions typically appeared in protruding portions of grains that was likely resistant to GBS, and low-angle boundaries were found to emerge at the core–mantle boundaries via slipping of dislocations within the mantle regions.
Influence of Superplastic Forming on Reduction of Yield Strength Property for Ti-6Al-4V Fine Grain Sheet and Ti-6Al-4V Standard
Authors: Sartkulvanich P. , Li Don , Crist Ernest , Yu K.O.
Published: January 2016

The SPF experiments were conducted on two sheet materials: Ti-6Al-4V Fine Grain Sheet (Ti-64 FGS) and Ti-6Al-4V Standard (Ti-64 STD) to investigate the influence of SPF conditions on the reduction of yield strength (YS) and change in microstructure for those two products. Results show that a) Ti-64 FGS has better formability at high testing strain rate than Ti-64 STD, b) initial YS values of Ti-64 FGS is 10% higher than Ti-64 STD, c) reduction of YS in Ti-64 FGS is 15-27%, which is much higher than 4-9% YS reduction for Ti-64 STD, d) the most influential factor on YS reduction is the forming temperature for Ti-64 FGS, but is the strain rate for Ti-64 STD, and e) microstructure pictures of initial Ti-64 FGS before forming is finer and more isotropic than Ti-64 STD, but Ti64 FGS shows more grain growth after SPF, which results in greater drop of yield strength.
Processing, Superplastic Properties and Friction Stir Welding of Fine-Grained AZ31, AZ91, AE42 and QE22 Magnesium Alloys
Authors: Ryspaev Talant , Janecek M. , Kral Robert , Wesling Volker , Wagner Lothar
Published: January 2016

The grain refinement after thermo-mechanical treatment (TMT) was investigated in AZ91, AE42, und QE22 magnesium alloys. The optimal over-aging temperature was determined to be 300 °C in the case of AZ91 and AE42 alloys and 350 °C for QE22 alloy.
After optimized TMT, the average grain sizes were 13.5 µm (AE42), 11.1 µm (AZ91) and 1.9 µm (QE22). The QE22 alloy exhibited the superior superplastic properties, with maximum elongation to failure 750 % and strain rate sensitivity parameter m=0.73.
The Friction Stir Welding showed that the original base material grain structure of the alloys AZ31 and AZ91 replaced by ultrafine grains in the stir zone.
The purpose of the present paper is to present the results of the grain refinement in magnesium alloys by thermo mechanical treatment and stir welding.
Fabrication of Dense Nanostructured Bulk Ceramics by Means of Spark-Plasma-Sintering (SPS) Processing
Authors: Morita Koji , Kim Byung Nam , Yoshida Hidehiro , Hiraga Keijiro , Sakka Yoshio
Published: January 2016

In order to fabricate fine-grained and dense nanoceramic materials, the effect of spark-plasma-sintering (SPS) conditions was examined in MgAl2O4 spinel as a reference material. The SPS conditions, such as heating rate and loading temperature, strongly affected the microstructures. Although the density can be improved with decreasing the heating rate to less than 10 °C/min, it requires a long processing time. In order to fully utilize the high heating rate that is a primary advantage of the SPS technique, load controlling is very effective to achieve high density with maintaining fine grain size. An increase in the loading temperature during SPS processing can reduce the residual porosity in a spinel even at the widely used high heating rate of 100 °C/min. This suggests that for the SPS processing in ceramics, the load controlling is an important factor as well as the heating rate and sintering temperature.
Energy Absorption of Superplastic Zn-22Al Alloy Foam Manufactured through Melt Foaming Process
Authors: Ogawa Satoshi , Sekido Kenji , Kitazono Koichi
Published: January 2016

Closed-cell superplastic Zn-22Al alloy foams were manufactured through the melt foaming process using sodium hydrogen carbonate powder as a foaming agent. Foaming tests were carried out under different foaming temperatures, times and additive amounts of foaming agent. The porosity of Zn-22Al alloy foams were between 30 and 70%. The cell wall consisted of fine equiaxial crystal grains after solution treatment. The compressive properties of the Zn-22Al alloy foams were investigated at room temperature and high temperature. Zn-22Al alloy foams exhibited high strain rate sensitivity, which was caused by superplastic deformation of the cell wall material.
High-Temperature-Tensile-Deformation Behavior of Ti-6Al-4V Alloy with the Acicular α′ Martensite Microstructure
Authors: Nishihara Takuro , Matsumoto Hiroaki , Iwagaki Yohei , Shiraishi Tohru , Ono Yoshiki
Published: January 2016

Titanium alloys are widely used in aerospace components, with the most widely used alloy being (α+β)-type Ti-6Al-4V (hereafter designated as Ti-64) alloy owing to its high specific strength and high formability associated with superplasticity. This work examines the tensile deformation behavior of the Ti-64 alloy with the acicular α′ martensite microstructure tested at from 700°C to 900°C. Higher tensile-elongation and higher strain-rate-sensitivity value are seen in the Ti-64 alloy with the α′ martensite microstructure as compared to that with the lamellar (α+β) microstructure. During deformation of the α′ martensite microstructure at 700°C or 800°C, acicular microstructure evolves into fine equiaxed (α+β) structure, whereas there is no apparent change in microstructure in the case of the lamellar (α+β) starting microstructure. This result indicates that dynamic globularization during deformation is strongly enhanced in the acicular α′ martensite starting microstructure, thereby leading to higher tensile elongation.
Superplastic Deformation Behavior in Dual-Phase Mg-Ca Alloy
Authors: Yano Takahiko , Ikeo Naoko , Watanabe Hiroyuki , Mukai Toshiji
Published: January 2016

Superplastic deformation behavior was investigated for a dual-phase Mg-Ca alloy. The elongation-to-failure reached more than 120% with the strain rate sensitivity, m, over 0.4. The activation energy required for the deformation was estimated to be 98 kJ/mol which is close to the activation energy for grain boundary diffusion in magnesium. Therefore, the superplastic deformation mechanism was suggested to be the grain boundary sliding rate, which is controlled by boundary diffusion.
Effects of Initial Microstructure and Deformation Method on Grain Refinement in a Cu-Cr-Zr Alloy
Authors: Shakhova Iaroslava , Belyakov Andrey , Kaibyshev Rustam
Published: January 2016

The development of submicrocrystalline structure in a Cu-0.3wt.%Cr-0.5wt.%Zr during multidirectional forging (MDF) and equal channel angular pressing (ECAP) was investigated in comparison. A large number of strain-induced subboundaries with low-angle misorientations appeared at early deformation. The subsequent straining led to an increase in the misorientations of these subboundaries, resulting in the formation of submicrocrystalline structure at sufficiently large strains. The process of microstructural evolution can be considered as continuous dynamic recrystallization. MDF provided faster kinetics of new ultrafine grain formation as compared to ECAP. The fraction of ultrafine grains with a size below 2 μm comprised 0.59 or 0.23 after MDF or ECAP to a total strain of 4, respectively. The grain refinement kinetics could be accelerated by the presence of second phase precipitates. The fraction of ultrafine grains after MDF to a strain of 4 achieved 0.36 or 0.59 in the solution treated or aged samples, respectively.
Microstructural Evolution of Body-Centred Cubic Fe-Al Alloy by Friction Stir Processing with SiC Particles Addition
Authors: Nagaoka Toru , Kimoto Yoshihisa , Watanabe Hiroyuki , Fukusumi Masao , Morisada Yoshiaki , Fujii Hidetoshi , Bhadeshia H.K.D.H.
Published: January 2016

The surface of body-centred cubic Fe-7Al (mass%) alloy plate was successfully modified by friction stir processing with SiC particles addition. The stir zone with SiC addition had an average grain size of 5.9 μm, smaller than that of 10.1 μm in the stir zone without SiC addition. SiC particles introduced by friction stir processing were converted to fine Fe3AlCx particles by reaction with the ferrite matrix. The hardness near the surface of the stir zone was significantly increased to 351 HV by introduction of particles, compared to the hardness of 200 HV in the stir zone without particles addition. The dispersed particles also contributed to suppression of grain growth of the matrix at elevated temperature.
Two-Dimensional Molecular Dynamics Simulation for Studying of Grain Refinement
Authors: Baimova Julia A. , Dmitriev Sergey V.
Published: January 2016

The molecular dynamics simulation method in two-dimensional case is presented for the simulation of grain refinement and can be applied to the investigation of grain boundary sliding and defects movement under severe plastic deformation. Nanopolycrystalline system is shown as the example of the application of the method proposed. Atomistic details of structure formation and grain growth (refinement) are shown by the example of change of loading scheme. It was shown that elongated grains which appear under plastic deformation can grow up even larger or be destroyed, depending on the direction of the applied maximal shear stresses.
Superplasticity in a 5024 Aluminium Alloy Subjected to ECAP and Subsequent Cold Rolling
Authors: Mogucheva Anna , Yuzbekova Diana , Kaibyshev Rustam
Published: January 2016

The superplastic behavior of an 5024 alloy, subjected to equal-channel angular pressing (ECAP) followed by extensive cold rolling (CR), was studied in the temperature range 250-500°C and at strain rates ranging from 10–4 to 10–1 s–1. The maximum elongation-to failure of ~1440% with a corresponding strain rate sensitive coefficient m of ~0.42 was attained at 450°C and a strain rate of ~1.4×10–1 s–1. The relationship between superplastic properties and microstructure of the alloy was discussed.
Constitution of ISO and JIS for Method of Tensile Testing of Superplastic Materials
Authors: Kitazono Koichi , Takayama Yoshimasa , Motohashi Yoshinobu , Ono Fumio
Published: January 2016

Method for tensile testing of superplastic materials had been standardized as ISO 20032: 2007, which is based on JIS, Japanese Industrial Standard, H 7501 and H 7505. These standards specify the test specimens of S-and R-types. Recently, the working group organized by Osaka Science and Technology Center, Japan, proposed a revised version of ISO 20032 with several corrections. After systematic review and voting at ISO/TC (Mechanical Testing of Metals) 164/SC2 (Ductility Testing), the second edition of ISO 20032 was published in 2013. Now, a working group has been set for proposing a revised version of JIS corresponding to ISO 20032: 2013. This paper reports the constitution process of these ISO and JIS standards.