bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of PDMS Dome-Shaped Membrane and its Performance Analysis Using FEA for Fluidic Based Flow Sensor
Authors: Mat Nawi Mohd Norzaidi , Abd Manaf Asrulnizam , Arshad Mohd Rizal , Sidek Othman
Published: November 2014

The dome-shaped membrane was designed for the fluidic based flow sensor for the underwater sensing. It has the diameter of 5mm and thickness within 0.2mm. The simple fabrication process for the dome shaped structure was demonstrated using casting and molding processes. The effect of the fabrication process was investigated by measuring the thickness of the dome-shaped membrane for different sample. For the performance analysis, the actual shape which was the same with the fabricated shaped was simulated and compared with the ideal shape using finite element analysis for the same input flow rate. The membrane sensitivity of the actual shape decreased from 163.4 μm/ms-1 to 133.33 μm/ms-1 compared to the ideal shape based on the displacement of the membrane over input fluid velocity.
Preparation and Characterization of Newly Developed Polysulfone/Polyethersulfone Blend Membrane for CO2 Separation
Authors: Mannan Hafiz Abdul , Mukhtar Hilmi , Murugesan Thanabalan
Published: November 2014

Polymeric membranes suffer from so called upper bound tradeoff between permeability and selectivity as described by Robeson. Polymer blending is a valuable technique to tune the properties of polymeric membranes by physical mixing of different polymers in a single mixture. In this study, preparation and characterization of newly developed polysulfone/polyethersulfone (PSF/PES) blend flat sheet dense membranes is described for CO2/CH4 separation. Blend membranes with different blending ratios were prepared and the developed membranes were characterized by FESEM, FTIR and TGA to see the effect of blend ratio on morphology, bonding and thermal stability respectively. Permeability of CO2 and CH4 gases in pressure range of 2-10 bar is recorded to find out the ideal selectivity of prepared membranes. The results are discussed and compared with individual polymer membranes.
Modeling of Mullins Effect on Laminated Rubber-Metal Spring
Authors: Salim Mohd Azli , Abdullah Mohd Azman , Putra Azma
Published: November 2014

This paper presents the Mullins effect on the laminated rubber-metal spring analytically modeled using lumped parameter system. The general form of the equation is developed to represent the multi-degree-of-freedom system for layer of embedded metal plates. The Mullins effect can be observed when a compression load is applied to the spring. It is shown that by increasing the embedded metal plate, the Mullins effect inside the rubber is reduced due to the improved stiffness in vertical direction.
Vortex Formation for Different Geometry of Cavities Using High Reynolds Number
Authors: Saadun Mohd Noor Asril , Sharudin Muhammad Zulhakim , Che Sidik Nor Azwadi , Mohd Hanafi Mohd Hafidzal
Published: November 2014

A preliminary study of Computational Fluid Dynamics (CFD) on the effect of high Reynolds numbers in the cavity has been carried out. Two dimensional model analysis of the flow characteristics were conducted using the numerical solution of Navier-Stokes equations based on the finite difference method. The flow characteristics in the cavity and the driven flow were modeled via turbulence equation modelling. This paper focuses on the effects of different high Reynolds number on the flow pattern of contaminant removal in the cavity. Different types of geometry and aspect ratio of the geometry were used as the parameters of the cavity in this study. Based on visualization of flows between each model with the different parameters used, the results of a comparison analysis focusing on the behavior of the flow were reported.
Mixing Quality Improvement of a Coaxial Syngas Mixer by Adding Optimized Mechanical Tabs Using Three-Dimensional CFD Modeling
Authors: Danardono Dominicus , Kim Ki Seong
Published: November 2014

A coaxial gas mixer is designed for mixing air and synthesis gas or syngas as fuel. Three-dimensional computational models are harnessed to analyze and predict the influence of the mechanical tabs aspect ratio and number on the mixing characteristics and performance of the gas mixer. Attention is concentrated on the influence of mechanical tabs on the air-fuel ratio, pressure loss and mixing quality. The optimum design of the mechanical tab was realized with aspect ratio of 0.32 and 4 tabs with 45o tab angle. The coaxial gas mixer using the optimized mechanical tabs was realized with λ of 1.13 corresponding to pressure loss of 37.2 Pa at 100 m3/h air-flow rates and the coefficient of variation (CoV) of mixing was 0.29. The gas mixer with the mechanical tabs had much better mixing performance than the gas mixer without mechanical tabs with only relatively small increase in pressure loss.
Thermal Efficiency of the Photovoltaic Thermal System with Serpentine Tube Collector
Authors: Rosli Mohamad Afzanizam Bin Mohd , Misha Suhaimi , Sopian Kamaruzzaman , Mat Sohif , Sulaiman Mohd Yusof , Salleh Elias
Published: November 2014

Photovoltaic thermal (PVT) system is one of the renewable energy resources that produce electric and thermal energy simultaneously. One of the key parameters to ensure good performance of the PVT is the design of the collector absorber. In this study, a thermal model of the PVT was developed to predict the thermal efficiency of the system. Simulations were conducted on four configurations of the serpentine tube. Results showed that the best design could achieve 50% thermal efficiency at zero reduced temperature. Our findings indicate that the shape, gap, and diameter of the tubes of the absorber are crucial to the good performance of the PVT.
The Investigation of Coupling-Unwanted Signal to the Solar Panel Material due to Induced Overvoltage Created by Short Spark Gap
Authors: Abdul Rahim Nur Hidayu , Baharudin Zikri Abadi , Othman Md Nazri
Published: November 2014

Photovoltaics (PV) system converts light into electric current using the photo-electric effect. Due to the growing demand for renewable energy sources, the manufacturing of solar cells and PV system arrays has advanced considerably in recent years. However, lightning protection on photovoltaic material is very crucial to avoid strike damage caused by transient overvoltage to the photovoltaic system that may due to a direct or an indirect strike. There is no experimental study recently to show the profile of unwanted signals due to induced overvoltage that is coupled to the solar panel system or related material. It is consequently imperative that experimental work to investigate the unwanted signal that is coupled to the solar panel material be conducted. In this study, the experimental set up of induced overvoltage was conducted in which the unwanted signal due to induced voltage was created by the short spark gap. The experiment was conducted in a High Voltage lab in University Teknikal Malaysia Melaka (UTeM) using artificial lightning discharge of 1.2/50μs with the peak voltage of 33 kV. The distance between the solar panel and spark gap was varied in order to study the relationship between the maximum voltage of unwanted signal and the distance. The existence of unwanted signal due to induced voltage with of maximum voltage profile was observed and is discussed in detail in the result and discussion sections.
Performance Assessment of Slip Mode Frequency Shift (SMS) Islanding Detection Methods
Authors: Sapar Ahmad Farid , Gan Chin Kim , Shamshiri Meysam , Ramani Anis Niza
Published: November 2014

The awareness concerning the grid connected Photovoltaic (PV) has become vital and a major concern nowadays. Islanding detection is one of the most dominant challenges for distributed generation system connected to the utility grid. In addition, islanding has not been a preferable option as it may pose safety hazard and may cause damage to power generation and power supply facilities as a result of unsynchronized re-closer. Therefore, the islanding detection techniques are needed to ensure safe and reliable system operation. One of the established islanding prevention methods is the Slip Mode Frequency Shift (SMS) islanding method, which has numerous advantages over the other techniques. This paper investigates the active islanding detection methods and specifically focused on the SMS islanding method. The results show that the SMS islanding method successfully detected an unintentional fault and managed to isolate the system within the prescribed time range.
Design and Simulation of Small Heliostat Field at Universiti Teknologi PETRONAS Campus
Authors: Gamil Ahmed , Gilani Syed Ihtsham Ul Haq , Al-Kayiem Hussain Hamoud
Published: November 2014

Solar Power Tower systems have attracted the worldwide interest since the early 1980s and heliostat fields have been an area for development due to their high cost and important function. This paper presents a mathematical model to design a small heliostat field with 3 dual-axis heliostat units located in Universiti Teknologi PETRONAS, Malaysia. The model mainly relies on the sun position and tower and heliostat geometrical relations, namely, tower height and the ground distance of the concerned heliostats. The heliostat field layout is configured according to radial staggered pattern then varying the tower height and heliostat ground distance to calculate the facing and target angle of each heliostat. TRNSYS software was used to simulate the power output for the proposed heliostat field. The modeled heliostat field could deliver 10 kW for 12.4 m2 reflective area for latitude 4.3̊ N. A solar power tower testing facility will be built according to the design specifications produced in this paper and TRNSYS simulation results are required to estimate the power input to the receiver system for sizing purpose in the future.
Pt-Based Catalytic Microcombustor for Micropower Generation
Authors: Muhamad Nazri Murat , Muhamad Azman Miskam , Mohd Azmier Ahmad , Zainal Alauddin Zainal Alimuddin , Mohammad Zulfikar Ishak
Published: November 2014

This paper presents the fabrication and characterization of platinum-based catalytic microcombustor. The platinum catalyst was deposited onto type-304 stainless steel using the wet impregnation method. The stainless steel undergoes controlled conversion coating treatment in sulfuric acid solution to increase the porosity of its surface before the deposition of the platinum catalyst. The scanning electron microscopy result showed that the porosity on the stainless steel surface will depend on the length of treatment time in the sulfuric acid solution. The surface porosity increased as the treatment time increases. The stainless steel surface morphology changed from smooth to ‘cracked-mud’ morphology after treatment in sulfuric acid solution. The treatment time also provide significant effect to the amount of platinum deposited on the stainless steel surface. The energy dispersive x-ray analysis showed that the amount of deposited platinum for 10 seconds of treatment time was 0.68 wt%, whereas those for 20 and 30 seconds were 0.87 wt% and 1.10 wt%, respectively. Liquefied petroleum gas-air combustion result showed that the flame completely submerged inside the microcombustor with a catalyst, whereas portions of flame can be observed at the exhaust for the microcombustor without a catalyst. The minimum air-to-fuel ratios before the combustion blow-out for 10, 20, and 30 seconds of treatment time was 0.5, 0.4, and 0.3 respectively.
An Experimental Study on the Performance and Emissions of Diesel Engine Fuelled with Biodiesel Derived from Palm Oil
Authors: Jaat M. , Khalid Amir , Manshoor Bukhari , Ramsy Him , Mustaffa Norrizal
Published: November 2014

The use of biodiesel as an alternative fuels in the diesel engine is very effective due to less of emissions and high performance. This study investigated the effect of palm oil blending and engine speed on performance and emission in diesel engine. The performance of biodiesel blends were investigated in terms of brake power, fuel consumption rate, flywheel torque, while emissions parameter was tested in terms of smoke opacity, hydrocarbon (HC), nitrogen oxide (NOx), carbon oxide (CO), carbon dioxide (CO2) and oxygen (O2) at various engine speed 1500, 2000, 2500 and 3000 revolution per minute (rpm). Biodiesel was blended with ordinary diesel fuel in various proportions. The engine was tested up to 50% load conditions by using Ordinary Diesel (OD), B5, B10 and B15 fuels. The properties of biodiesel fuel were tested including density, kinematic viscosity, water content and flash points test. Experimental results indicated that biodiesel blend shows the flywheel torque obtained is higher compared to the OD but fuel consumption rate and the brake power are quite similar when tested at ambient temperature. All biodiesel blends released good emissions compared to the OD. The CO2, CO, HC and O2 content released from the biodiesel fuels were clearly lower than the normal fuel except for NOX contents. Biodiesel released higher smoke opacity compared to OD at all range of engine speeds under 50% load condition. In conclusion, biodiesel fuels are found to offer better performances and emissions and are suitable to be used in unmodified diesel engine.
The Use of Untreated Waste Cooking Oil and Diesel Fuel Blends as IC Engine Fuels
Authors: Isa Ali Md. , Shahrir A. , Faizal W.M. , Iskandar M.T.
Published: November 2014

In the present experimental investigation, untreated waste cooking oil (UWCO) was used as an alternative fuel for a diesel engine. The high viscosity of the UWCO was reduced by blending with ordinary diesel. The blends of varying proportions of UWCO and diesel were prepared, analyzed and compared with diesel fuel. Measurements of chemical and physical properties have indicated a good potential of using UWCO as an alternative diesel engine fuel. The results showed that blends containing 5 to 40% of UWCO in diesel yielded the properties closely matching that of diesel. The performance of the engine using blends of UWCO was evaluated in a four cylinder diesel engine and compared with the performance obtained with diesel. Significant improvement in the engine performance was observed. The results showed that the addition of 30% UWCO with diesel produced higher brake power with a reduction in exhaust emission such as CO2 and NOx. The specific fuel consumption and the exhaust temperature were increased due to decrease in viscosity of the UWCO. Acceptable thermal efficiencies of the engine were obtained with blends containing up to 30% volume of UWCO. From the properties and engine test result, it has been established that 10-30% of UWCO can be substituted for diesel without any engine modification.
Remote Terminal Unit Developed for Distribution Automation System (DAS) Using MPLAB Software
Authors: Ab Ghani Mohd Ruddin , Wan Jusoh Wan Nor Shela Ezwane , Raman Siti Hajar , Mat Hanafiah Mohd Ariff , Wan Hassan Wan Ahmas Redhauddin , Jano Zanariah
Published: November 2014

Remote Terminal Unit (RTU) is a standalone data acquisition and control unit which monitors and controls an equipment at a remote location from the central station that utilizes Distribution Automation System (DAS). The RTU acquires information such as measured values, signal, meter readings and it transmits command or instruction, sets points, controls variables and monitors function time. In the present Distribution Automation System (DAS), the distribution field of automation allows the utilities to implement a flexible control of distribution system to enhance efficiency, reliability, and quality of electric service. The implementation of distribution automation system is highlighted based on two factors; benefit and area of distribution automation system implementation. The hardware design uses PIC16F877A microcontroller to control all the functions of RTU. The types of fault detected are undervoltage and overcurrent. The design consists of MPLAB software development using C programming and hardware assembly. RTU is also designed to communicate with the Supervisory Control and Data Acquisition (SCADA) system and resulting in RTU’s ability to detect undervoltage and overcurrent fault.
Computer Simulation of New High Capacity and Low-Loss HVDC Transmission for Sustainable Energy Systems
Authors: Zakaria Zahriladha , Mohammed Sabah Ramadhan
Published: November 2014

This paper presents a new technique for the design of high voltage direct current (HVDC) transmission system to transmit the electrical energy generated by sustainable energy sources to load center located at far distances. The problems with high power capacity and power loss of high voltage alternating current (HVAC) system particularly in long distance transmission, has led to emerge new technology which is HVDC transmission. Therefore, with the development of high voltage valves, it is possible to transmit DC power at high voltages and over long distances. Simulation results show that the HVDC has the capability to produce ±1000 kV with high power capacity of 3 GW and efficiency equal to 98% for load center located at 1000 km. The simulation of this study is implemented using MATLAB/Simulink software. This study provides an insight and useful for the design of future HVDC transmission technology to deliver a large amount of electricity over long distance efficiently.
Comparing Cooling Energy between Existing Air-Conditioning System and Proposed Design System
Authors: Syafiq Syazwan M.M. , Yusof M.Z.M. , Chang C.K. , Amir Abdullah M.D.
Published: November 2014

Air-conditioning (AC) system is typically used to remove the sensible and latent heat loads in buildings. It provides cool and dehumidified air to meet the occupants comfort and good indoor air quality (IAQ). Improper design and analysis of AC process resulted in high cooling energy and unsatisfied indoor humidity level in tropical climate. The objective of this study is to identify the cooling energy in hotel restaurant by comparing the design with proper fresh air ventilation design. The hotel restaurant was designed with primary air unit (PAU) and air handling unit (AHU) as to remove sensible and latent loads. The performance of the AC system has been monitored and analysed using psychrometric chart. For the AC air side system, 296.2 kW of cooling energy was used in standard operation. An alternative design was proposed for the said hotel restaurant employing only one AHU, with a cooling capacity of 165.9 kW which was 43 % lower than the existing system. The difference in temperature, humidity ratio and air flow rate influenced the cooling energy for AC system.
Theoretical Analysis on Energy Consumption for Industrial Robots
Authors: Mohd Kazim Mohd Nor Fakhzan , Mohd Shah Hairol Nizam , bin Muhammad Nasir Muhammad Dzulhaxif
Published: November 2014

This paper presents a theoretical analysis on energy consumption for industrial robots. In this project, the industrial robot used is a virtual robot resembling the FANUC LR Mate 200iB robotic arm. The first two joints consume the most electrical energy, this research focuses only on the first two joints. The calculation of the electrical energy consumed is based on a previous established research done by Herman (2009) from Universiti Teknikal Malaysia Melaka (UTeM) in the year 2009. In this research, three different time intervals were used to set the speed of the robotic arm to be at 50%, 100% and 200% speed and they were tested on 10 different angles with 10 time intervals for the 1st and the 2nd robotic joints.
Physical and Chemical Activation Effect on Activated Carbon Prepared from Local Pineapple Waste
Authors: Yacob Abdul Rahim , Azmi Adlina , Amat Mustajab Mohd Khairul Asyraf
Published: November 2014

The characteristics and quality of activated carbons prepared depending on the chemical and physical properties of the starting materials and the activation method used. In this study, activated carbon prepared using pineapple waste. Three parts of pineapple waste which comprises of peel, crown and leaf were studied. For comparison activated carbon were prepared by both physical and chemical activation respectively. Three types of chemicals were used, phosphoric acid (H3PO4), sulphuric acid (H2SO4), and potassium hydroxide (KOH). The preparation includes carbonization at 200°C and activation at the 400°C using muffle furnace. The chemical characterization of the activated carbon was carried out using Thermogravimetric analysis (TGA), Nitrogen gas adsorption analysis and Fourier transform infrared (FTIR). The highest BET surface area was achieved when the pineapple peel soaked in 20% phosphoric acid with a surface area of 1115 m2g-1. FTIR analysis indicates that the reacted pineapple waste successfully converted into activated carbons.
Performance Evaluation of Adaptive Indoor Matched Rake Receiver Using Multiple-Combining Techniques
Authors: Fayadh Rashid Ali , Abd Malek Mohd Fareq , Fadhil Hilal Adnan , Saudin Norshafinash
Published: November 2014

This paper discusses the enhancement of the wireless rake receiver for high speed and short distance indoor ultra wideband (UWB) propagation with line-of sight (LOS) and non line-of sight (NLOS) channel models. The proposed matched rake receiver uses three main combining techniques, maximum ratio combining (MRC), equal gain combining (EGC), and selective combining (SC) to capture most of the energy of the multi-path components (MPCs). When the wireless communication systems work with high capacity and high speed in transmission and reception scenarios, there will be a serious challenge defined as inter-symbol interference (ISI) during the reception process. The ISI causes increasing in the bit error rate (BER) when the wireless communication systems work with high bit rate propagation. The matched rake receiver scheme was designed to suppress ISI by maximizing the signal to noise ratio (SNR) before constructing the desired signal in decision circuit and effectively the system enhancement is improved. After adding additive white Gaussian noise (AWGN) to the received signal, the improvement is cleared comparing with the theoretical results that has no AWGN. During the comparison of the simulation results, MRC partial rake receiver of less complexity showed better performance than the EGC and SC rake receivers.
Effect of Alkali and Water Content on Setting Time and Strength of Fly Ash Based Geopolymer
Authors: Asif Afshan , Man Zakaria , Azizli Khairun Azizi , Hamidi Rashidah Mohammed
Published: November 2014

The current work presents the effect of alkali concentration and water content on fly ash based geopolymer material. In this paper geopolymer material was prepared where Si/Al ratio (1.85: 1) is fixed and solid to water ratio (S/W) and NaOH concentration (4M, 8M, 12M) were varied. All samples were tested to establish the roles of water and alkali on the setting time and strength. At low solid to water ratio, (S/W= 3:1), the water quantity is high and the hardening of gel phase take more time. However, as water content is reduced from S/W 3:1 to 4:1 ratio, the setting point decreased significantly and only small change in setting time is observed when S/W shifted from 4:1 to 5:1. Sample prepared with 8M of NaOH showed the highest compressive strength. In this regards, Fourier transform infrared spectroscopy (FTIR) results support this observation where broad band (asymmetric strectching band) become sharper and shift towards lower wavenumber (1082.36 cm-1 to 985.16 cm-1). This finding shows that, to obtain required processing time at desired mechanical strength (20-30 Mpa) for a specific application of geopolymer, the suitable amount of water must be established.
Solid Waste Management and Treatment in Malaysia
Authors: Ismail Norasyikin , Ani Farid Nasir
Published: November 2014

A huge amount of solid wastes are generated daily in Malaysia. A staggering amount of municipal solid waste (MSW) is produced by one person daily in both urban and rural areas. Apart from these there would also be wastes that come from sewage sludge, industrial waste, agricultural waste, and clinical waste. Statistics of waste generated in Malaysia from each sector mention is presented in this paper. As the population of the country keep expanding, so does the generation of solid waste. However, we could take advantage of the situation by converting these wastes into syngas; which is known to be potentially capable in replacing natural gas for industrial and consumer’s energy application. In addition, existing treatment and processing of biomass and solid fuels such as coal has been widely used in industrial scales to generate electricity. Treatment of solid waste is one of many ways to manage this massive amount of solid waste generated.
Passenger Comfortability Studies of Electric Vehicle under ISO-2631 Criteria
Authors: Wibowo Wibowo , Ubaidillah Ubaidillah , Candra Ipnu , Nizam Muhammad
Published: November 2014

The study focuses on the vertical, longitudinal and lateral responses of ride performance of an electric vehicle. Issues related to the design of vehicle model with passive suspension system are discussed. A full-car seven-degrees-of-freedom model is used to investigate the dynamic responses by applying road disturbances in sinusoidal road input excitation. Frequency response of the heave, roll and pitch of the sprung mass is obtained for the need of studying the effects of given variations of the suspension stiffness coefficient and the suspension damping coefficient. Finally, using the ISO-2631 criteria, the result of the responses in frequency domain are evaluated to evaluate the passenger comfortability.
A New Method in Producing Ni Deposited Hydroxyapatite Composite by Modification of Electroless Deposition Technique
Authors: Sri Asliza M.A. , Mohd Zaheruddin K. , Rahmat Azmi , Jamaludin Shamsul Baharin , Ahmad Khairel Rafezi
Published: November 2014

Ni deposited Hydroxyapatite powder was prepared by electroless deposition technique without sensitization and activation treatments. The composition and phase of deposition were studied. The surface morphologies and composition of initial pure HA powder, as received Ni deposited HA powder and compacted Ni deposited HA powder after sintering were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) respectively. The phases in the powder before and after sintering were investigated by x-ray diffraction (XRD). From the experiment, with the increase of reduction agent, the plating time becomes shorter and optimal concentration of reduction agent and powder ratio is 3:1. The result shows that Ni succesfully deposited on HA powder and confirmed by EDX result. The Ni grain size distribution of 75nm to 250nm can be clearly observed on the HA surface from the micrograph after sintering. Decomposition of hydroxyapatite into α-TCP (α tricalcium phosphate) and TTCP (tetracalcium phosphate) did not occur in nickel deposited HA before and after sintering. On the other hand, a sharp Ni peak were detected
A Comparative Study on the Role of Precursors of Graphitic Carbon Nitrides for the Photocatalytic Degradation of Direct Red 81
Authors: Theerthagiri J. , Senthil R.A. , Madhavan J. , Neppolian B.
Published: November 2014

The graphitic carbon nitride (g-C3N4) materials have been synthesized from nitrogen rich precursors such as urea and thiourea by directly heating at 520 °C for 2 h. The as-synthesized carbon nitride samples were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-vis) absorption spectroscopy, photoluminescence (PL) and particle size analysis. The photoelectrochemical measurements were performed using several on-off cycles under visible-light irradiation. The x-ray diffraction peak is broader which indicates the fine powder nature of the synthesized materials. The estimated crystallite size of carbon nitrides synthesized from urea (U-CN) and thiourea (T-CN) are 4.0 and 4.4 nm respectively. The particle size of U-CN and T-CN were analysed by particle size analyser and were found to be 57.3 and 273.3 nm respectively. The photocatalytic activity for the degradation of the textile dye namely, direct red-81 (DR81) using these carbon nitrides were carried out under visible light irradiation. In the present investigation, a comparison study on the carbon nitrides synthesized from cheap precursors such as urea and thiourea for the degradation of DR81 has been carried out. The results inferred that U-CN exhibited higher photocatalytic activity than T-CN. The photoelectrochemical studies confirmed that the (e--h+) charge carrier separation is more efficient in U-CN than that of T-CN and therefore showed high photocatalytic degradation. Further, the smaller particle size of U-CN is also responsible for the observed degradation trend.
Dielectric Relaxation Study on TiO2 Based Nanocomposite Blend Polymer Electrolytes
Authors: Ambika C. , Hirankumar G.
Published: November 2014

Nanocomposite solid polymer electrolytes comprise of PMMA (poly methyl methacrylate), PVP (poly vinyl pyrolidone), MSA (methanesulfonic acid) and TiO2 as nanofiller were prepared by solution casting technique at different compositions. Sample with 1 mol% incorporated TiO2 has shown maximum conductivity and its value was found as 2.82 ×10-5 S/cm. The value of conductivity has been enhanced to about 31% upon the addition of nanofiller. The relaxation time for all the prepared composites as well as for the composite having maximum conductivity at various isotherms have been calculated from the loss tangent plot. The frequency and temperature dependence of dielectric constant and dielectric loss nanocomposite solid polymer electrolytes have also been studied. The modulus analysis confirms the non-Debye type formalism in the prepared composites.
Influence of Estimation Methods of Power Spectral Density Function on the Calculated Fatigue Life with Spectral Method
Authors: Niesłony Adam , Böhm Michał , Materac Agnieszka
Published: November 2014

Spectral method is one of the most effective methods of fatigue life estimation. In this method fundamental parameters characterizing the load process are determined on the basis of Power Spectral Density (PSD) function. PSD function can be obtained in many ways. Several functions from parametric methods, nonparametric methods and subspace method from Matlab package were discussed in this paper in terms of their use for the determination of fatigue life. Finally, calculated fatigue life was determined using spectral method and cycle counting method and compared using probability distributions of amplitudes according to Dirlik and Miner rule for damage summation.
Analysis of the Fatigue Life of Sintered Porous 316L Steel with Different Density
Authors: Falkowska Anna , Seweryn Andrzej
Published: November 2014

The paper presents the results of strength and fatigue life of porous sintered 316L stainless steel. Samples with different porosity ( 26%, 33% and 41%) were tested. Graphs of fatigue life were obtained. Both areas of crack initiation propagation and destructions of the samples were determined.
The Influence of In-Plane Constraint on Void Behavior in Front of a Crack in Plane Strain
Authors: Galkiewicz Jaroslaw
Published: November 2014

This paper investigates voids’ behavior in front of a crack in elastic-plastic material under plane strain condition. Using the modified boundary layer approach for selected values of Q-stress it evaluates the deformations of a material cell. The deformations are recomputed with an exact three-dimensional model.
Method for Monitoring the Destruction Process of Materials Using a High-Speed Camera and a Catodioptric Stereo-Vision System
Authors: Garbacz Piotr , Czajka Piotr , Burski Bartłomiej
Published: November 2014

The article presents a method for monitoring the destruction process of materials under mechanical load on a universal testing machine. Observations of the subjects are made using a high-speed camera and a catadioptric stereo-vision system. The camera allows for data acquisition with the capture speed more than a million frames per second (FPS) with reduced resolution. Catadioptric vision systems use mirrors and lenses in order to modify the observation path. In the proposed system four mirrors are required to divide the observation path into two separate paths. This enables monitoring the test specimens from different perspectives, which provides a number of advantages including information redundancy or stereovision. In order to verify the proposed method several metal specimens were put under mechanical load and monitored with the vision system. Test results are enclosed in the article. Selected registered images presenting the moment of the destruction are described in greater detail with data about the capture speed provided. The tests were conducted under front and back lighting in order to assess the best method of illumination.
Experimental Study of Non-Uniform Distribution of Basic Mechanical Parameters in Steel-Titanium Bimetal
Authors: Sołtysiak Robert , Boroński Dariusz , Karolczuk Aleksander , Kowalski Mateusz
Published: November 2014

The scope of this work is to study the process of explosive welding on basic strength properties of the welding interface layer and layers of the material which is near the welding interface. For this purpose the results of tests of basic strength properties in selected layers of steel-titanium bimetal (S355J2, titanium Grade 1) made by explosive welding are presented in the work. Tests were carried out by using mini-samples taken from the welding interface and from places located near the welding interface. Strength tests were carried out on the original system for strength tests - Micro Fatigue System (MFS). Strain during the tests was defined on the basis of a field analysis of dislocations in the camera's field of observation by use of the digital image correlation method. The conducted tests showed that the explosive welding process had impact upon basic strength parameters of the material of particular layers of the plated product.
Shear Strength Testing of Bonded Joints of Dental Materials
Authors: Wirwicki Mateusz , Topoliński Tomasz
Published: November 2014

Zirconium dioxide is a material more and more used by technicians and dental surgeons due to its chemical composition and excellent mechanical strength. It features high biocompatibility and may be used even in 6-unit fixed dental bridges. Adhesive bonding is one of the methods used in dental applications. New generation bonding agents featuring high mechanical strength are widely available on the market. This article presents the equipment designed and manufactured to European Standards for bonded joint testing as well as specimen geometry and bonding method. Monotonic and fatigue tests of bonded joints were performed, the results were presented and Weibull analysis was performed.
Influence of Adhesive Layer on Mechanical Properties of Multilayer Pipes
Authors: Piotrowski Michał , Mroziński Stanisław
Published: November 2014

In the paper the assessment was made of the influence of adhesive layer on strength properties of multilayer pipes. The conducted tests revealed that during the multilayer pipe’s construction process it is necessary to take into account the adhesive’s immediate strength, fatigue life and the change in their values depending on the temperature and the loading working on the pipe in the exploitation conditions. The adhesive’s influence or the lack thereof on the fatigue life depends on the level of stress σmax. This influence is minimal in the area of the greatest working stress and increases along with the decrease of stress.
Application of Vibration for Energy and Data Transfer in Mechanical Constructions; Energy Harvesting
Authors: Kaleta Jerzy , Lewandowski Daniel , Wiewiórski Przemysław
Published: November 2014

The work presents a method of at once power and information transmission through pair of rails using SURPS (Smart Ultrasonic Resonant Power System). The solution allows to (electrically) feed sensors located in hardly accessible places of mechanical constructions with simultaneous half-duplex data transmission (e.g. measurement “question-response”), when conventional power supply (requiring e.g. electricity networks, storage batteries, batteries, etc.) is eliminated. The mechanism of power transmission consists in “sending” of mechanical energy through an actuator in a form of “pure” sinusoidal ultrasonic wave and next “receiving” it and transforming into useful electrical current by a harvester. Both magnetostrictive and piezoelectric harvesters/actuators were used. For information transfer F2F (frequency - double frequency) procedures were used, they are a kind of FM (Frequency Modulation). To optimise transmission (the highest possible efficiency and acceptably low noise level), software allowing to select the right type of an actuator, modulation and the recommended frequency band was developed. Additionally it is possible to determine resonance frequency for each construction which is to be used for information and power transfer.
Determination of Dynamic Characteristics of Welded Joints Made of Steel S460NL
Authors: Barnat Wiesław , Kordys Marek
Published: November 2014

Examination of the behavior of materials under very high speed plastic deformation are widely used during the designing process of dynamically loaded steel structures. Steel is widely used as a basic material for designing engineering structures. Characteristics of steel obtained under static experiments are different from those obtained during static tests.
Analysis of Strain Distribution in Notch Zone in Aluminium FSW Joints for Irregular Fatigue Loading Conditions
Authors: Boroński Dariusz , Sołtysiak Robert , Lutowski Zbigniew
Published: November 2014

Joining aluminium alloys with the use of welding techniques often impairs their strength properties and in some cases it is very difficult or even impossible. An alternative method for joining this type of material is friction welding including FSW welding. The airplane aluminium alloy 2024-T3 is an example of material that can be welded using this method. Heat emitted during the process, which contributes to the material plasticisation in the zones of welding, causes significant changes in the material structure, thus affecting the joint properties. Fatigue life calculations of this type of joint can be performed according to different approaches. One of them is a local approach which requires knowledge of local strains or stresses within the notch zone. This paper is a presentation of exemplary results of experimental and numerical tests of strain in the zone of notch that occur in a joint under time variable loading.
Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions
Authors: Magee N. B. , Miller A. , Amaral M. , Cumiskey A.
Published: November 2014

Abstract. Here we show high-magnification images of hexagonal ice crystals acquired by environmental scanning electron microscopy (ESEM). Most ice crystals were grown and sublimated in the water vapor environment of an FEI-Quanta-200 ESEM, but crystals grown in a laboratory diffusion chamber were also transferred intact and imaged via ESEM. All of these images display prominent mesoscopic topography including linear striations, ridges, islands, steps, peaks, pits, and crevasses; the roughness is not observed to be confined to prism facets. The observations represent the most highly magnified images of ice surfaces yet reported and expand the range of conditions in which rough surface features are known to be conspicuous. Microscale surface topography is seen to be ubiquitously present at temperatures ranging from −10 °C to −40 °C, in supersaturated and subsaturated conditions, on all crystal facets, and irrespective of substrate. Despite the constant presence of surface roughness, the patterns of roughness are observed to be dramatically different between growing and sublimating crystals, and transferred crystals also display qualitatively different patterns of roughness. Crystals are also demonstrated to sometimes exhibit inhibited growth in moderately supersaturated conditions following exposure to near-equilibrium conditions, a phenomenon interpreted as evidence of 2-D nucleation. New knowledge about the characteristics of these features could affect the fundamental understanding of ice surfaces and their physical parameterization in the context of satellite retrievals and cloud modeling. Links to supplemental videos of ice growth and sublimation are provided.
The POLARCAT Model Intercomparison Project (POLMIP): overview and evaluation with observations
Authors: Emmons L. K. , Arnold S. R. , Monks S. A. , Huijnen V. , Tilmes S. , Law K. S. , Thomas J. L. , Raut J.-C. , Bouarar I. , Turquety S. , Long Y. , Duncan B. , Steenrod S. , Strode S. , Flemming J. , Mao J. , Langner J. , Thompson A. M. , Tarasick D. , Apel E. C. , Blake D. R. , Cohen R. C. , Dibb J. , Diskin G. S. , Fried A. , Hall S. R. , Huey L. G. , Weinheimer A. J. , Wisthaler A. , Mikoviny T. , Nowak J. , Peischl J. , Roberts J. M. , Ryerson T. , Warneke C. , Helmig D.
Published: November 2014

Abstract. A model intercomparison activity was inspired by the large suite of atmospheric chemistry observations made during the International Polar Year (2008) in the Arctic. Nine global and two regional chemical transport models have performed simulations for 2008 using a common emissions inventory to quantify the differences in model chemistry and transport schemes. This paper summarizes the models and compares their simulations of ozone and its precursors, and presents an evaluation of the simulations using a variety of surface, balloon, aircraft and satellite observations. Despite using the same emissions, large differences are seen among the models. Differences in a number of model parameters are identified as contributing to differences in the modelled chemical species, including cloud fields and photolysis rates. The largest differences among models, and between models and observations, are in NOy partitioning (PAN vs. HNO3) and in oxygenated volatile organic compounds (VOCs) such as acetaldehyde and acetone. Comparisons to surface site measurements of ethane and propane indicate that the emissions of these species are significantly underestimated. While limited in spatial and temporal coverage, the aircraft measurements provide a simultaneous evaluation of many species. Satellite observations of NO2 from OMI have been used to evaluate the models over source regions, indicating anthropogenic emissions are underestimated in East Asia, but fire emissions are generally overestimated. The emission factors for wildfires in Canada are evaluated using the correlations of VOCs to CO in the model output in comparison to enhancement factors derived from aircraft observations, showing reasonable agreement for methanol and acetaldehyde, but underestimate of ethanol, propane and acetone, while overestimating ethane emission factors.
Characteristics of tropopause parameters as observed with GPS radio occultation
Authors: Rieckh T. , Scherllin-Pirscher B. , Ladstädter F. , Foelsche U.
Published: November 2014

Abstract. Characteristics of the lapse rate tropopause are analyzed globally for tropopause altitude and temperature using global positioning system (GPS) radio occultation (RO) data from late 2001 to the end of 2013. RO profiles feature high vertical resolution and excellent quality in the upper troposphere and lower stratosphere, which are key factors for tropopause determination, including multiple ones. RO data provide measurements globally and allow examination of both temporal and spatial tropopause characteristics based entirely on observational measurements. To investigate latitudinal and longitudinal tropopause characteristics, the mean annual cycle, and inter-annual variability, we use tropopauses from individual profiles as well as their statistical measures for zonal bands and 5° × 10° bins. The latitudinal structure of first tropopauses shows the well-known distribution with high (cold) tropical tropopauses and low (warm) extra-tropical tropopauses. In the transition zones (20 to 40° N/S), individual profiles reveal varying tropopause altitudes from less than 7 km to more than 17 km due to variability in the subtropical tropopause break. In this region, we also find multiple tropopauses throughout the year. Longitudinal variability is strongest at northern hemispheric mid latitudes and in the Asian monsoon region. The mean annual cycle features changes in amplitude and phase, depending on latitude. This is caused by different underlying physical processes (such as the Brewer–Dobson circulation – BDC) and atmospheric dynamics (such as the strong polar vortex in the southern hemispheric winter). Inter-annual anomalies of tropopause parameters show signatures of El Niño–Southern Oscillation (ENSO), the quasi–biennial oscillation (QBO), and the varying strength of the polar vortex, including sudden stratospheric warming (SSW) events. These results are in good agreement with previous studies and underpin the high utility of the entire RO record for investigating latitudinal, longitudinal, and temporal tropopause characteristics globally.
Impact of droughts on the carbon cycle in European vegetation: a probabilistic risk analysis using six vegetation models
Authors: Van Oijen M. , Balkovi J. , Beer C. , Cameron D. R. , Ciais P. , Cramer W. , Kato T. , Kuhnert M. , Martin R. , Myneni R. , Rammig A. , Rolinski S. , Soussana J.-F. , Thonicke K. , Van der Velde M. , Xu L.
Published: November 2014

Abstract. We analyse how climate change may alter risks posed by droughts to carbon fluxes in European ecosystems. The approach follows a recently proposed framework for risk analysis based on probability theory. In this approach, risk is quantified as the product of hazard probability and ecosystem vulnerability. The probability of a drought hazard is calculated here from the Standardized Precipitation–Evapotranspiration Index (SPEI). Vulnerability is calculated from the response to drought simulated by process-based vegetation models. We use six different models: three for generic vegetation (JSBACH, LPJmL, ORCHIDEE) and three for specific ecosystems (Scots pine forests: BASFOR; winter wheat fields: EPIC; grasslands: PASIM). The periods 1971–2000 and 2071–2100 are compared. Climate data are based on gridded observations and on output from the regional climate model REMO using the SRES A1B scenario. The risk analysis is carried out for ~ 18 000 grid cells of 0.25 × 0.25° across Europe. For each grid cell, drought vulnerability and risk are quantified for five seasonal variables: net primary and ecosystem productivity (NPP, NEP), heterotrophic respiration (Rh), soil water content and evapotranspiration. In this analysis, climate change leads to increased drought risks for net primary productivity in the Mediterranean area: five of the models estimate that risk will exceed 15%. The risks increase mainly because of greater drought probability; ecosystem vulnerability will increase to a lesser extent. Because NPP will be affected more than Rh, future carbon sequestration (NEP) will also be at risk predominantly in southern Europe, with risks exceeding 0.25 g C m−2 d−1 according to most models, amounting to reductions in carbon sequestration of 20 to 80%.