bluuebunny/crossref_metadata_2025 huggingface dataset:
Introducing an Application of a Charged Coupled Device (CCD) in an Optical Tomography System
Authors: Jamaludin Juliza , Abdul Rahim Ruzairi , Abdul Rahim Herlina , Fazalul Rahiman Hafiz , Mohd Muji Siti Zarina , Mohd Fadzil Naizatul Shima , Pei Ling Leow , Jumaah Fahjumi , Ahmad Anita , Nor Ayob Nor Muzakkir , En Hong Ling
Published: April 2015

A tomographic system is a method used for capturing an image of an internal object section. Optical tomography is one method which widely used in medical and industrial fields. This paper reviews several applications of Charged Coupled Devices (CCD) and introduces an application of a CCD in an optical tomography system. Most of the previous research used this component for displacement measurement and as a video camera. This paper discusses its basic principle of operation, basic construction, its criteria, application, and its advantages compared to other optoelectronic sensors  available in today’s market. The applications of this sensor in fields such as astronomy and medical has proved the ability and the good performance of CCD in capturing images. This sensor should widen its usage in optical tomography fields because it can give high performance in image reconstruction.
An Accurate Operation of Wideband Multi-Port Reflectometer with New Calibration Method implementing Least Mean Square for Microwave Imaging Application
Authors: Che Yob Rashidah , Seman Norhudah
Published: April 2015

The wideband operation of multi-port reflectometer may lead to inaccurate reflection coefficient measurement caused by the overlapped phase characteristics of the used calibration standards. Therefore, a calibration procedure implementing Least Mean Square (LMS) is proposed to offer accurate operation of wideband multi-port reflectometer from 1 to 6 GHz. Its well wideband performance is verified by attenuators of 3, 6 and 10 dB that assessed as the device under tests (DUTs). The proposed LMS contains a learning rate, m and updated weight coefficient, W(k+1) to eliminate error and achieve the corrected reflection coefficient of DUT.
Evaluation Of Volumetric Properties And Resilient Modulus Performance Of Nanopolyacrylate Polymer Modified Binder (NPMB) Asphalt Mixes
Authors: Shaffie Ekarizan , Ahmad Juraidah , Arshad Ahmad Kamil , Kamarun Dzraini
Published: April 2015

This paper presents the potential benefits of nanopolyacrylate (NPA) for the asphalt mixtures used on pavement. This research evaluates the resilient modulus performance of dense graded Superpave-designed HMA mix. Two different types of dense graded Superpave HMA mix were developed consists of unmodified bitumen mix (UMB) and nanopolyacrylate modified bitumen mix (NPMB). Nanopolyacrylate polymer modified bitumen was prepared from addition of 6 percent of NPA polymer into asphalt bitumen. Resilient modulus results from Resilient Modulus test were determined to evaluate the performance of these mixtures. Results showed that all the mixes passed the Superpave volumetric properties criteria which indicated that these mixtures were good with respect to durability and flexibility. The Resilient modulus result of NPMB demonstrates better resistance to rutting than those prepared using UMB mix. It was estimated that the average resilient modulus values for both UMB and NPMB mixtures are decreased by 80 percent when the test temperature increased from 25ºC to 40ºC.   In conclusion, the addition of NPA to the binder has certainly improved the bitumen properties significantly and hence increase the resistant to rutting of the asphalt mixture.
Pavement Technology Elements in Green Highway
Authors: Aifa W. N. , Hainin M.R. , Abd.Majid M.Z. , MohamadZin R. , Yaacob H. , Zakaria R. , Bujang M.
Published: April 2015

A technology that has been experienced during the construction of a pavement has indicated the improvement in exploring the advanced technology pavement. Types of technologies of pavements applied are always related to the high performance of the pavements during the life span. Indeed, the application of technology in pavement has insisted to reduce the rate of environmental problems such as global warming, abundance of solid waste and so on. The development of technologies in pavement has been identified by the expert in highway engineering as one of the initiatives in response the sustainability requirement that later on will be applied to implement green highway concepts. Nowadays, the process of selecting a variety of green pavement technology element is becoming more challenging to be evaluated qualitatively. This paper aims to determine critical pavement technology element based on ranking of priority to achieve the objective of the green highway design. It is necessary to determine the critical elements in order to identify which elements will most contribute to the green practices based on the priority level of the weighted factor value. Therefore, a questionnaire survey was developed and distributed to the respondent in order to obtain the agreement level for the element. Based on the weighted analysis, it has been shown that the soil erosion control element has achieved first ranking in order to implement green highway and followed by permeable and cool pavement.In conclusion, the identification of critical elementsof green pavement technology is the main key towards sustainable development in the future.
Performance of Modified Asphalt Binder with Tire Rubber Powder
Authors: Hainin Mohd. Rosli , A. Aziz Md. Maniruzzaman , Adnan Abbas Mukhtar , Abdul Hassan Norhidayah , Putra Jaya Ramadhansyah , Y Liu Hong
Published: April 2015

The two major distresses associated with flexible pavement are rutting deformation and fatigue cracking in world highways. This is mainly because of the increasing load and higher tire pressure of vehicles which are applied to highway pavements today. At the same time, the asphalt containing neat binders does not always performed as expected. As a consequence, these distresses reduce the design life of the pavement and increase the maintenance costs tremendously. Therefore, in order to minimize the distresses and increase the durability of asphalt pavement, there is need to improve the performance properties of neat asphalt binders. Many researchers reported that using different types of polymer to modify the asphalt binder could be a solution to minimize the distresses occurred in asphalt pavement and improve the overall performance of the pavement. Disposal of waste tires is a serious environmental concern in many countries. Several attempts were made in the past to modify asphalt binder using tire rubber powder to improve the performance of neat asphalt binders. It is believed that the use of Tire Rubber Powder (TRP) as an additive in the modification of asphalt binder can improve the binder performance properties, increase the durability of the pavement, and reduces the waste disposal problem. This study aims to review the previous studies conducted on the use of tire rubber powder in the modification of asphalt binder. It was observed that addition of tire rubber powder to the asphalt binder enhances the properties of modified binder. It was found that an increase in the percentage of tire rubber powder causes an increase in rutting factor (G*/sinδ) and decrease in fatigue factor (G*sinδ) indicating higher resistance against rutting and fatigue cracking. In addition, the use of tire rubber powder to modify asphalt binder is considered as a solution to enhance environmental and economic sustainability of pavements.
Strength and Microstructure Properties of Double Layered Concrete Paving Blocks Containing Waste Tyre Rubber Granules
Authors: Jusli Euniza , Md Nor Hasanan , Putra Jaya Ramadhansyah , Haron Zaiton
Published: April 2015

This paper aims to examine the effect of replacing the natural aggregate with waste tyrerubber granules. Waste tyrerubber granules were used as aggretate replacement in the pavingblock at four different percentage: 10%, 20%, 30%, and 40%. The paving blocks were tested in terms of their strength and the characteristics of their microstructure by measuring compressive strength, flexural strength, splitting tensile strength, and skid resistance. Field scanning electron microscopy (FESEM) and Fourier Transform Infra-Red(FTIR) analysis werecarried out on the paving block specimen. When 10% of the natural aggregate was replaced with waste tyrerubber granules, there was no substantial difference in the compressive strength but the flexural and splitting tensile strength increased to a certain extent. When more than 20% of waste tyrerubber granulesis incorporated in the paving blocks, the strength is acutely reduced even though there is a growth in ductility. The results proved that even after failure, the paving blocks did not shatter but still stayed imperforated. Double layer rubberized concrete paving blocks (DL-RCPBs) are more flexible and soft to the surface, and thus provide a better ride quality. This characteristic makes it suitable for trafficked roads. DL-RCPBs (30% and 40%) with low strength characteristics could be used on roads that not required high strength and may be viable for other applications, depending on the percentage of waste tyre rubber used. DL-RCPB with higher waste tyre rubber content exhibit higher skid resistance especially on dry surface but reduced on slippery surface. Two main factors that influence the skid resistance are high elasticity and rough surface texture of waste tyre rubber. It is suggested that DL-RCPBs could be introduced as one of alternative concrete paving block (CPB) that can be used in paving application.
Utilization of Sewage Sludge Molten Slag as Aggregate Substitute in Asphalt Mixtures
Authors: Mohd Jakarni Fauzan , Md Yusoff Nur Izzi , Wu Jiantao , A Aziz Md Maniruzzaman
Published: April 2015

Sewage sludge is one of the final products from wastewater treatment processes. Handling and disposal of sewage sludge has become one of the major economic and environmental concerns. Instead of simply treating and disposing, high temperature melting treatment is considered as one of the effective alternative efforts to utilize sewage sludge as reusable materials. High temperature melting is defined as the method of melting sewage sludge at temperature of about 1500°C before cooling the molten sludge to become solidified materials, known as molten slag. Past studies have shown that high temperature melting treatment could convert sewage sludge into reusable products without adverse environmental effects. The objective of this study is to evaluate the possible utilization of sewage sludge molten slag as aggregate substitute in asphalt mixtures for pavement construction applications. The whole concept of this study was designed to assess the materials characteristics and suitability, and thus to evaluate the performance of asphalt mixtures with sewage sludge molten slag as aggregate substitute in terms of Marshall stability and flow tests. Based on the conducted study, it can be concluded that sewage sludge molten slag fulfilled almost all the standard requirements for aggregates in asphalt mixtures and can be utilized as partial replacement for aggregates. Sewage sludge molten slag has shown to be able to resist wear, polishing effect and weathering actions.
Evaluation of Effects of Extended Short-Term Aging on the Rheological Properties of Asphalt Binders at Intermediate Temperatures Using Respond Surface Method
Authors: Hamzah Meor Othman , Omranian Seyed Reza , Golchin Babak , Hainin Mohd Rosli
Published: April 2015

Predicting the effects of short term aging on asphalt binders’ rheological properties can be a complicated task.  This is due to the exposure of different binders to different conditions. Hence, the utilization of a Respond Surface Method (RSM) is a practical way to predict these effects. An experimental matrix was planned to predict asphalt binders behavior at intermediate temperatures based on the central composite design for aging duration and test temperature. The test results showed that prolonging aging increased the binder complex modulus, but decreased the phase angle, while increasing the test temperature decreased the complex modulus but increased the phase angle. However, the trends in aging differ and depend on the binder type, test temperature and aging conditions. It was also found that the RSM method is a fast, effective and reliable tool to predict the effects of aging on binders’ rheological behavior.
The Interpretations of Gated Communities from the Malaysian Gating Experience
Authors: Z Ainur Zaireen, , K. Hussin, , A. L. Maslinda, , M. Y. Norhidayah, , M. N. Razali, , M. N. Noorsidi Aizuddin, , A. H. Mohammed, , Z. Siti Radiaton Adawiyah,
Published: April 2015

Principally, gated community is a walled and guarded housing area that is managed by some sort of internal governance. However, this interpretation is hardly generalizable since the experience with gating differs between countries. This paper attempts to place another input of international comparison in learning gated community characters in the literature, particularly in showing how the gating experiences may influence the interpretation of this housing form within a local setting. From the review made on the Malaysian experience, it was clear that the gated communities were entirely a market-driven product; the supply was dominated by private housing developers; and, hassimilar characters as mentioned above. However, with government intervention, the interpretation of this housing form has changed until it is now not simply a walled and guarded housing area with internal governance, but mainly characterised by its tenure. This situation implies that the understanding of gated communities between the policy and the practice is conflicting; thus, becomes a significant basis for further studies on the industry players’ preferences in developing gated communities.
Exploring Critical Success Factors of Energy Management for Sustainable Building in Malaysian University
Authors: Abdullah Saleh Alia , Mohammed Abdul Hakim , Abdullah Mat Naim
Published: April 2015

Universities are increasingly consuming energy due to its population with various activities. Thus, Malaysian Higher Education Ministry insisted all parties involved to take the initiatives in reducing the energy consumption. Focusing on the importance of practicing energy management (EM) effectively, this paper discusses the Critical Success Factors (CSFs) towards sustainable university. Structured interviews, pilot study and a questionnaire survey were conducted. The findings disclose the relative importance of the 23 number of identified CSFs. In order to explore the underlying relationship among the identified CSFs, factor analysis method was adopted, which leads to grouping the 23 identified CSFs into four groups.
Assessment of Forest Encroachment Using Remote Sensing Technique. Case Study: Mentigi Forest Reserve, Cameron Highlands
Authors: Mat Zin Mohd Hayyi , Ahmad Baharin
Published: April 2015

Agriculture is one of the biggest and profitable activities in Cameron Highlands, Malaysia. High quality plantation products such as tea, vegetable, fruits and flower have high demand in Malaysia. These profitable activities however have caused illegal agriculture and farming. Farmers tend to extent their farm by encroaching government lands and take advantage on any open space for illegal farming. These encroachment activities have affected forest reserve area including Mentigi Forest Reserve (MFR). This study is to identify and evaluate the encroachment activities within MFR area using multiple remote sensing datasets (SPOT 5 and IKONOS). Cadastral parcel map was used to delineate the MFR area and also provide the actual size of MFR area. Hybrid classification method was used on remote sensing image to classify the land-cover in the study area. Ground truth data from field observation were used to assess the accuracy of the classification. Results of this study showed the technique used was able to identify encroachment activities such as agriculture and development. The total encroachment area in MFR was about 2.8 ha in 2001 and has increased to about 7.3 ha in 2010. These encroachment areas represent 0.39% and 1.46% respectively. This area might be small but it may affect the forest ecosystem which can lead to hazardous natural disaster if not well monitored and managed.
Housing Bubble in Penang Prediction and Determinants
Authors: Yun Lu Loh , YM Lee Janice , Al-mulali Usama , Ahmad Nurul Afiqah , Mohammad Izran Sarrazin
Published: April 2015

House prices in Malaysian cities increased drastically in the past few years, notably in the state of Penang.  The existence of a housing bubble is speculated by major property players. This paper ascertains whether a housing bubble exists in Penang and explores the long-run and short-run determinants of Penang residential prices. Quarterly data (2000Q1 to 2012Q2) of House Price Index is the dependent variable and Gross Domestic Product, Consumer Price Index (CPI), Base Lending Rate (BLR) and Housing Supply as independent variables. Econometric model together with fully modified Ordinary Least Squares regression were used to detect the presence of housing bubble in Penang. The determinants of Penang house prices are based on Granger causality and variance decomposition analysis using the vector autoregressive (VAR) model. The results show no evidence of housing bubble in Penang housing market. CPI has both long-run and short run causality relationship with house prices while CPI and BLR explain a large part of housing price variance. Results show changes in inflation and cost of borrowing will greatly affect Penang house prices.
Child Safety Policy in High-Rise Building as Preventive Measures of Child Falls–A Review
Authors: Yusuf Sitiayu Zubaidah , Hussin Khadijah , Azali Nur Husna
Published: April 2015

Urbanization is one of the factors that lead to the high-rise buildings construction and vertical commercial development in developed countries especially in high density area to ensure that housing stock is sufficient. The continuous growth of high-rise residential properties indicates that there is a need for an effective property management system to provide a sustainable high-rise residential property development. The children who live in high-rise residential would be exposed to danger or accident especially risk of fall from height and currently has been occurring nation-wide for many years resulting serious injuries and deaths. This incident can be avoided by incorporating simple child safety designs into new homes or by providing child safety features into existing homes. However, this matter requires the intervention of policy and legislation for the enforcement of the implementation. Hence, this paper attempt to reviews the literature concerning the needs of policy related to child safety for high-rise residential in order to control an accident involving children falls. The outcome of this study hopefully will ensure the implementation of child safety policy in order to prevent child falls and make sure the building is safe to be occupied especially for children.
Individual Tree Measurement in Tropical Environment using Terrestrial Laser Scanning
Authors: Abdul Rahman Muhammad Zulkarnain , Majid Zulkepli , Abu Bakar Md Afif , Rasib Abd Wahid , Wan Kadir Wan Hazli
Published: April 2015

Detailed forest inventory and mensuration of individual trees have drawn attention of research society mainly to support sustainable forest management. This study aims at estimating individual tree attributes from high density point cloud obtained by terrestrial laser scanner (TLS). The point clouds were obtained over single reference tree and group of trees in forest area. The reference tree is treated as benchmark since detailed measurements of branch diameter were made on selected branches with different sizes and locations. Diameter at breast height (DBH) was measured for trees in forest. Furthermore tree height, height to crown base, crown volume and tree branch volume were also estimated for each tree. Branch diameter is estimated directly from the point clouds based on semi-automatic approach of model fitting i.e. sphere, ellipse and cylinder. Tree branch volume is estimated based on the volume of the fitted models. Tree height and height to crown base are computed using histogram analysis of the point clouds elevation. Tree crown volume is estimated by fitting a convex-hull on the tree crown. The results show that the Root Mean Squared Error (RMSE) of the estimated tree branch diameter does not have a specific trend with branch sizes and number of points used for fitting process. This explains complicated distribution of point clouds over the branches. Overall cylinder model produces good results with most branch sizes and number of point clouds for fitting. The cylinder fitting approach shows significantly better estimation results compared to sphere and ellipse fitting models.
Accuracy Assessment of LIDAR-Derived Elevation Value Over Vegetated Terrain in Tropical Region
Authors: Ismail Zamri , Abdul Rahman Muhammad Zulkarnain , Mohd Salleh Mohd Radhie , Mohd Yusof Abdul Razak
Published: April 2015

Airborne LiDAR has been widely used to generate good quality of Digital Terrain Model (DTM). Normally, good quality of DTM would require high density and quality of airborne LiDAR data acquisition which increase the cost and processing time. This study focuses on investigating the capability of low density airborne LiDAR data captured by the Riegl system mounted on an aircraft. The LiDAR data sampling densities is about 2.2 points per m2. The study area is covered by rubber trees with moderately dense understorey vegetation and mixed forest. The ground filtering procedure employs the adaptive triangulation irregular network (ATIN) technique. A reference DTM is generated using 76 ground reference points collected using total station. Based on this DTM the study area is divided into different classes of terrain slopes. The point clouds belong to non-terrain features are then used to calculate the relative percentage of crown cover. The overall root mean square error (RMSE) of elevation values obtained from airborne LiDAR data is 0.611 m. The slope of the study area is divided into class-1 (0-5 degrees), class-2 (5-10 degrees), class-3 (10-15 degrees) and class-4 (15-20 degrees). The results show that the slope class has high correlation (0.916) with the RMSE of the LiDAR ground points. The percentage of crown cover is divided into class-1 (60-70%), class-2 (70-80%), class-3 (80-90%) and class-4 (90-100%). The correlation between percentage of crown cover and RMSE of the LiDAR ground points is slightly lower than the slope class with the correlation coefficient of 0.663.
An Overview of the Forecasting Methods Used in Real Estate Housing Price Modelling
Authors: Munusamy Mohan , Muthuveerappan Chitrakala , Baba Maizan , Abdullah @ Mohd Asmoni Mat Naim
Published: April 2015

Forecasting is very fundamental in real estate where the past transactions become the evidences while decision making for the present and the future. Several techniques and validation approached that were commonly used in housing price index forecasting. Beside the appropriate forecasting method, error calculation is one of the critical constraints in accuracy out of all methods. This paper overview the available methods and the types of error being considered in forecasting techniques. Then the forecasting methods, namely Multiple Regression Analysis (MRA) and Artificial Neural Network which are highly applied in forecasting modelling are compared over its error accuracy.
Wrinkling of a Polymeric Gel During Transient Swelling
Authors: Toh William , Ding Zhiwei , Yong Ng Teng , Liu Zishun
Published: April 2015

When exposed to an external solvent, a dry polymeric network imbibes the solvent and undergoes large deformation. The resulting aggregate is known as a hydrogel. This swelling process is diffusion driven and thus results in differential swelling during transient swelling. When subjected to external geometrical constraints, such as being rigidly fixed or attachment to a compliant substrate, wrinkles have been shown to appear due to mechanical instabilities. In the case of free swelling, there are no external constraints to induce the instabilities accounting for wrinkling patterns. However, during the transient swelling process, the swelling differential between the gel on the exterior and the interior causes compressive stresses and gives rise to mechanical instabilities. It is also observed that the time dependence of the swelling profile causes the wrinkles to evolve with time. In this work, we investigate this interesting phenomenon of transient wrinkle mode evolution using the finite element and state-space methods. From our simulations and prediction, we find that there is an inverse relation between critical wave number and time, which has earlier been observed in experiments.
Convective Heat Transfer on Flat Plate at Very High Temperature and Pressure Gradient
Authors: Pedrosa A. C. F. , Nagamatsu H. T.
Published: April 2015

This paper describes heat transfer measurements on flat plates for various free-stream temperatures, pressure gradients, Reynolds numbers and Mach numbers anticipated in advanced gas turbines. A shock tube generated the high temperature and pressure air flow, and a variable geometry test section was used to produce inlet flow Mach number of 0.11 and accelerate the flow over the plate to sonic velocity. Thin platinum film heat gages recorded the local surface heat flux for laminar, transition, and turbulent boundary layers. The free-stream temperatures varied from 630°R (350°K) to 4700°R (2611°K) for a Tw/Tr,g temperature ratio of 0.82 to 0.12 and Mach numbers from 0.11 to 1.90. The Reynolds number based on the model length was varied from 8.8 × 102 to 5 × 106. The experimental heat flux data were correlated with the laminar and turbulent theories and the transition phenomenon was examined.
Turbine or Electric Motor Driven Gas Compressors on Production Platforms
Authors: Overli J. M. , Magnusson R.
Published: April 2015

This paper describes the results obtained from a study commissioned to ascertain the optimum drive arrangements for the gas compression machinery to be installed on an integrated platform in the North Sea.

The study was restricted to two main drive type alternatives:

- All compressor stages on one shaft driven by a variable speed aero-derivative gas turbine.

- All compressor stages with separate, constant speed, electric motor drives.

The study took into account drive option and shafting arrangements with regard to flexibility of operation, weight, area, lay-out, foundation/alignment, waste heat recovery requirements, availability/reliability, safety, maintenance, fuel consumption, investment cost and operational experience.

For the specific case studied, the overall conclusion was in favour of the gas turbine drive alternative.
Boundary Conditions for the Potential Equation in Transonic Internal Flow Calculation
Authors: Deconinck H. , Hirsch Ch.
Published: April 2015

An analysis of internal potential flow is presented showing the existence of multiple potential solutions with shocks for a given mass flow rate. These solutions are related to non isentropic Euler solutions.

Inflow and outflow boundary conditions are proposed which uniquely determine the shock position allowing the calculation of potential flows which are either choked or have a supersonic inlet.

Numerical computations using a multigrid finite element approach are presented and compared with exact quasi-one-dimensional Euler solutions confirming the ability of the potential method to solve accurately supersonic and choked nozzle flows.
Economics of High-Performance Regenerators
Authors: Valentino S. J.
Published: April 2015

Industrial energy conservation has become a topic of increasing concern in recent years since energy costs began to escalate rapidly. No longer is it adequate for users and project designers to evaluate equipment on first cost; instead prime consideration must be given to the costs of operation, maintenance, and availability. In the gas turbine area, considerable effort has been put forth to increase the cycle efficiency by heat recovery methods. While the technique is not new, use of very-high-effectiveness regenerators specifically designed to minimize maintenance downtime has increased in recent years. The resulting fuel savings offer a payback of 1 to 2 years; this payback, in conjunction with low maintenance, has made the use of high-performance equipment economically attractive. This paper presents fuel savings and evaluation techniques for several heavy-duty gas turbines, together with design features employed to achieve minimum downtime. Field experience on a number of installations also is presented.
Emissions Variability and Traversing on Production RB211 Engines
Authors: Hawkins H. L. , Bhangu J. K. , Priddin C. H. , Walker P. H.
Published: April 2015

In order to control the emissions from aircraft gas turbines, the International Civil Aviation Organisation (I.C.A.O.) and the U.S. Environmental Protection Agency (E.P.A.) have, through consultations with the various parties over the past decade, made firm proposals for an emission certification scheme, together with mandatory limiting levels for certain pollutants. The compliance with the proposed emission standards requires that a representative sample is collected from the engine exhaust plane and transported without changing its chemical composition to the analysis instruments. Despite clearly defined rules for sample transfer and analysis methods, the emissions measurement will be subject to variability due to the following factors:

a) engine-to-engine variability which will include the impact of dimensional tolerance on the combustor hardware and other components which affect the combustor performance,

b) sampling variation because of the nonuniform distribution of the pollutant species in the exhaust plane (see references 4,5), with the result that engine manufacturers are required to demonstrate “by means of detailed traverse measurements in the sampling plane” that a specific probe design provides a representative sample,

and

c) gas analysis instrumentation scatter that occurs in the actual analysis of identical samples.
Combustion Characteristics of Hydrogen - Carbon Monoxide Based Gaseous Fuels
Authors: White David J. , Kubasco Alan J. , LeCren Richard T. , Notardonato Joseph J.
Published: April 2015

An experimental rig program has been conducted with the objective of evaluating the combustion performance of a family of fuel gases based on a mixture of hydrogen and carbon monoxide. These gases, in addition to being members of a family, were also representative of those secondary fuels that could be produced from coal by various gasification schemes. In particular, simulated Winkler, Lurgi, and Blue-water low and medium energy content gases were used as fuels in the experimental combustor rig. The combustor used was originally designed as a low NOx rich-lean system for burning liquid fuels with high bound nitrogen levels. When used with the above gaseous fuels this combustor was operated in a lean-lean mode with ultra long residence times. The Blue-water gas was also operated in a rich-lean mode. The results of these tests indicate the possibility of the existence of an “optimum” gas turbine hydrogen - carbon monoxide based secondary fuel. Such a fuel would exhibit low NOx and high efficiency over the entire engine operating range. It would also have sufficient stability range to allow normal light-off and engine acceleration. Solar Turbines Incorporated would like to emphasize that the results presented here have been obtained with experimental rig combustors. The technologies generated could, however, be utilized in future commercial gas turbines.
The Microsynchronizer: A Microprocessor Based Synchronizing Relay
Authors: Near Timothy P. , Johnson Daniel
Published: April 2015

A generator power system synchronizer, the microsynchronizer was developed specifically for gas turbine generator drives. It provides improved performance and reliability as compared to synchro n izers used in the past, while at the same time it cuts costs of manufacturing and installation. Faster and more accurate synchronizing is achieved by including a speed matching function and utilizing more sophisticated algorithms. Higher reliability is obtained by minimizing parts count, eliminating adjustments, incorporating transient suppression, and designing “failsafe” features. The microsynchronizer was first installed in the field in early 1979, while more than 100 will be in service by the end of 1982.
Ceramic Applications in Turbine Engines (CATE) Development Testing
Authors: Helms H. E. , Thrasher S. R.
Published: April 2015

The objective of the CATE program was to apply ceramic components to the hot flow path of an existing vehicular gas turbine engine and thereby demonstrate the feasibility of structural ceramic components. To accomplish this the Allison IGT 404-4 gas turbine engine has operated at successively higher temperatures made possible by the introduction of ceramic components with performance and component durability demonstrations. Extensive ceramic material characterization, supplier process development work, development of non-destructive inspection (NDI) techniques, rig ceramic component development and proof testing, and engine demonstration testing have been conducted.

This paper describes the CATE Project concept for development testing of ceramic components for use in vehicular gas turbine engines. Included will be the approach to development testing, a description of the CATE GT 404 engine and the ceramic components designed for that engine, a summary of the development test experience accumulated on the ceramic components, an assessment of the results and benefits gained from the program, and recommendations for follow-on component development work.
Experimental and Numerical Investigation of a Large Cylindrical Oil-Fired Combustor
Authors: ElMahallawy F. M. , Khalil E. E. , Abdel Aal O.
Published: April 2015

The present work presents measurements of velocity, temperature and heat transfer rates carried out on a segmented water-cooled cylindrical oil-fired flame tube typical of a 0.56 kg/s packaged fire-tube steam boiler. A prediction procedure, that solves the conservation equations of the various entities, was successfully used to produce computed velocities, temperatures and heat flux distributions. A two-equation turbulence model, a combustion model and a discrete ordinate radiation model were used to approximate the various characteristics of the flow. The combustion model solved the Eulerian equations of the gas phase, and the Lagrangian equations of the droplet motion, heating, evaporation and combustion.
The GTCP331, a 600 HP Auxiliary Power Unit Program
Authors: Stohlgren L. M.
Published: April 2015

The Garrett GTCP331 series auxiliary power unit (APU) is currently entering airline service as a Category I -Essential APU with the Boeing and Airbus advanced transport aircraft. The GTCP331 APU serves as a secondary pneumatic and electrical power source for the aircraft systems, both on the ground and in-flight. As it enters airline service, the GTCP331 APU offers: sound design origin, advanced metallurgical technology, a rigorous test program background, state-of-the-art full authority digital electronic controls, and the application of acoustic attenuating techniques and materials. These facets combine to present user-airlines with a modern, high-technology APU that through lowered operating cost, and increased reliability and maintainability, meets the challenge of reduced cost of ownership.
Three-Dimensional Modeling of Horseshoe Vortex Flows
Authors: Turan A. , Ruggieri N. G. , Smith G. E. , Forbes B. C.
Published: April 2015

AVCO Lycoming’s circumferentially stirred combustor employs a well-established vortex, in the shape of a horseshoe with fuel injection at the apex, to promote mixing in each sector of the annulus. This paper presents the results of a three-dimensional viscous flow analysis of this horseshoe vortex flow field. The results agree well with flow visualization tests. Analytical results were also obtained for some variations of the basic configuration in which the horseshoe vortex fails to become well-established. These results highlight certain critical aspects of circumferentially stirred combustor designs. Thus the overall study has illustrated the substantial engineering contribution that can be made by three-dimensional modeling of the underlying flow fields in combustors employing highly structured, swirling flows.
Propulsion System Screening for Survivability and Effectiveness
Authors: Montague Hugh
Published: April 2015

Selection of engines has been traditionally concerned with performance capability. Although performance is still an essential element in all future applications, recognition of operational realities has placed importance on system survivability and ultimate cost. In advanced military aircraft design, it is necessary and feasible to evaluate propulsion systems in a combat context that will discriminate according to the cost of performing the required mission. Methods are outlined which can be utilized during parametric studies to permit the screening of candidate design options, and identification of trends and design drivers. This approach provides the analyst with the ability to assess the impact of survivability and vulnerability characteristics upon the selection of the proper engine and propulsion system for a given mission task in terms of a cost related figure of merit. The importance of early consideration of these requirements in the weapon system design process has been dramtically illustrated by a recent study concerning propulsion survivability and weapon system design. The first preliminary aircraft design was found to be unacceptably susceptible to radar-seeking threat missiles. Utilizing the analytical results, a modest redesign to the aircraft reduced the combat cost by a factor of sixty. The results present informative phenomenology, while the methods illustrated show an approach that provides early screening, rapid optimization and ability to focus on the significant design factors.
The Measurement of Turbomachinery Stator-to-Drum Running Clearances
Authors: Davidson David P. , DeRose Robert D. , Wennerstrom Arthur J.
Published: April 2015

The clearance between a compressor or turbine case and rotating blades or shrouds has been measured in a variety of ways over the years with varying degrees of accuracy. However, one critical clearance which has defied active measurement heretofore has been that between the tip of a cantilevered stator vane and an adjacent drum rotor. A significant number of turbomachines under development, representing many millions of dollars, have met an inglorious end through unanticipated rubs which were experienced in this area.

The present paper describes how a device which was introduced by its manufacturer for conventional rotor tip or shroud clearance measurements was applied to measure stator-vane-to-drum clearance. The installation technique is explained, and the results of vane-to-drum measurements made with a research compressor are presented. Adaptations of the same technique should permit similar measurements to be made within a turbine, and possibly on rotating seals buried deep within a turbomachine.
Experimental Investigation of Fuel Distribution in a Transverse Stream
Authors: Mao-lin Yang , Shan-jian Gu , Gao-en Liu , Xiang-yi Li
Published: April 2015

The results of an experimental investigation of fuel distribution downstream of a plain orifice injector in a transverse air stream are presented. The fuel concentration distribution at the survey plane downstream of the injector was determined with an iso-kinetic sampling technique and the pattern of fuel distribution was described. The empirical expressions for the centreline of a fuel spray (which was defined as the maximum fuel concentration line or penetration distance of the fuel jet) and for the peak value of the fuel concentration were obtained. An empirical method is proposed to predict the liquid fuel concentration distribution in the plane downstream of the injector and the fuel despersion contour line.
Redesign and Performance Analysis of a Transonic Axial Compressor Stator and Equivalent Plane Cascades With Subsonic Controlled Diffusion Blades
Authors: Dunker R. , Rechter H. , Starken H. , Weyer H.
Published: April 2015

In order to verify a new controlled diffusion blade design concept, the stator of an existing transonic axial compressor stage was redesigned. Stator and equivalent cascade tests revealed the potential of such blades for a considerably higher aerodynamic loading than it has been applied up to now.

The design procedure is described and the results of plane cascade and stage testing are submitted including performance analysis of both, cascade and stator blade sections, at design and off-design operating conditions.

The blade profile shapes and cascade geometries were calculated by means of an inverse 2-dimensional method taking also into account the axial velocity density ratio (AVDR). This design concept is essentially based on prescribed blade pressure distributions which are optimized with respect to the blade boundary layer development.

The flow phenomena are illustrated by means of loss and flow turning investigations, blade pressure distributions and laser velocimetry data.

The test results reveal that the 2-D approach applied is quite promising for the 3-D stator blade design. Finally overall and blade element performance comparisons between the original NACA 65 profiled stator and the redesigned one demonstrate the favourable flow behaviour of the new stator as well as the great potential of the controlled diffusion blade concept.
Vectoring Exhaust Systems for STOL Tactical Aircraft
Authors: Tape R. F. , Hartill W. R. , Curry S. , Jones T. J.
Published: April 2015

An analytical study has been performed to investigate the performance and application of four exhaust nozzle concepts with the potential to enhance the short takeoff and landing capabilities of advanced tactical aircraft for the 1990’s. The exhaust system concepts include side and rear exhaust thrust vectoring systems with axisymmetric and non-axisymmetric nozzles.

To investigate the application of the nozzle concepts, advanced tactical aircraft have been configured which will operate from 700 or 1000 feet fields. Four different propulsion system configurations were used, each producing glide slope equilibrium in a different way.

The characteristics of these STOL aircraft are compared with those of a CTOL aircraft designed to perform the same mission. The results show that the short field performance can be achieved with little aircraft TOGW or LCC penalty. The study also identifies promising configurations for STOL tactical aircraft.
Temperature Profile Development in Turbulent Mixing of Coolant Jets With a Confined Hot Cross Flow
Authors: Wittig S. L. K. , Elbahar O. M. F. , Noll B. E.
Published: April 2015

The mixing of coolant air jets with the hot gas exiting the primary zone is of major importance to the combustor exit temperature profile. Geometry and momentum flux ratios are the dominant parameters. A theoretical and experimental study of single as well as opposite wall jet injection into a hot cross flow reveals the applicability and limitations of existing correlations. Modified correlations are presented for opposite wall injection with jets of different momentum flux ratios. The advantages in applying field methods for describing the flow are discussed.
Gas Turbine Performance Improvement by Retrofit of Advanced Technology
Authors: Tendon V. C. , Zabrodsky A.
Published: April 2015

Development and operation of larger size gas turbines have demonstrated that higher turbine inlet temperature can be sustained due to advancement in material and cooling technology. After a feasibility study it was determined that modern available technology can be applied to existing previous generation of machines. These programs are identified as “The Performance Upgrade of Gas Turbine”. Amongst the significant benefits that can be realized by retrofitting state of art parts in existing machines are higher power and more durable parts. This paper discusses various programs that are currently offered and implementation technique of upgrading the machines. A recent example is also presented. These unique programs are particularly attractive at the time of overall life consumption of the initial set of hot parts. At that point in an operating gas turbine it will be beneficial to retrofit the latest configuration parts to realize the performance improvements.
Stiffness Derivative Finite Element Technique to Determine Nodal Weight Functions With Singularity Elements
Authors: Sha George T.
Published: April 2015

The use of the stiffness derivative technique coupled with “quarter-point” singular crack-tip elements permits very efficient finite element determination of both stress intensity factors and nodal weight functions. Two-dimensional results are presented in this paper to demonstrate that accurate stress intensity factors and nodal weight functions can be obtained from relatively coarse mesh models by coupling the stiffness derivative technique with singular elements.

The principle of linear superposition implies that the calculation of stress intensity factors and nodal weight functions with crack-face loading, σ(rs), is equivalent to loading the cracked body with remote loads, which produces σ(rs) on the prospective crack face in the absence of crack. The verification of this equivalency is made numerically, using the virtual crack extension technique. Load independent nodal weight functions for two-dimensional crack geometry is demonstrated on various remote and crack-face loading conditions. The efficient calculation of stress intensity factors with the use of the “uncracked” stress field and the crack-face nodal weight functions is also illustrated.

In order to facilitate the utilization of the discretized crack-face nodal weight functions, an approach was developed for two-dimensional crack problems. Approximations of the crack-face nodal weight functions as a function of distance, (rs), from crack-tip has been successfully demonstrated by the following equation:

h a , r s = A a √ r s + B a + C a √ r s + D a r s

Coefficients A(a), B(a), C(a) and D(a), which are functions of crack length (a), can be obtained by least-squares fitting procedures. The crack-face nodal weight functions for a new crack geometry can be approximated using cubic spline interpolation of the coefficients A, B, C and D of varying crack lengths. This approach, demonstrated on the calculation of stress intensity factors for single edge crack geometry, resulted in a total loss of accuracy of less than 1%.
Operating Experience With a Waste Heat Recovery System Installed on a Pipeline Compressor Station
Authors: Vogt G. M.
Published: April 2015

Construction of the Borsig waste heat recovery system at NOVA’s Clearwater Compressor Station is now complete. Initial operation of the system has been very encouraging.

This paper is an update on an earlier paper entitled “Pipeline Compressor Station with Waste Heat Recovery” by G. M. Holldorff, A. R. Hladun and S. A. Dunn. The process cycle including main components and control functions will be reviewed and their performance evaluated. Operating experience to date is also presented.

In emphasizing safety, NOVA has instituted unique operating and maintenance procedures to this system. These procedures are also outlined.