bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation and Analysis of Wall Cracks in Cement Stabilized Rammed Earth Technology
Authors: Kandamby G. W. T. C.
Published: November 2020

Cement stabilized rammed earth (CSRE) is one of the developed and affordable housing technologies, adopted in many countries, which has been used in Sri Lanka since 2004 for building single and two-floor houses. Steel slip-form and timber formwork have been used for casting walls. Information collected on wall cracks under these two methods is analyzed to justify the reasons for these cracks. Data collected at the initial stage of construction and its serviceability period of 12 years is considered under this study. Most of the walls have been in satisfactory condition, but few had to be repaired. CSRE wall tends to crack similar to other masonry technology due to faulty construction and environmental changes. Major issues are the cracks due to shrinkage of CSRE material which appeared after one year period of construction. Detailing the construction with the provision of shrinkage cracks is required to mitigate the vertical cracks on CSRE walls.
Energy Design and Optimization of a Greenhouse: A Heating, Cooling and Lighting Study
Authors: Belkadi A. , Mezghani D. , Mami A.
Published: November 2020

This paper presents a new approach to properly optimize the energy consumption in a greenhouse. An improved intermediate modeling to establish the energy balance in a greenhouse within a higher precision was adopted. While the classical model focuses on the efficient cooling and heating demands and neglects the profound impact of lighting parameters, it was shown that these three necessary components are interdependent, and they should be taken into account all together to comfortably reach optimal crop production and energy consumption. This study’s contribution is the classical model’s improvement and the demonstration of the fact that the heat released by the luminaries and the energy used by this equipment has fundamental consequences on the energy balance as well as the preferred choice of the possible shape of the greenhouse and its adequate cover.
Formulating Module Assessment for Improved Academic Performance Predictability in Higher Education
Authors: Alsuwaiket M. , Blasi A. H. , Al-Msie'deen R. A.
Published: November 2020

The choice of an effective student assessment method is an issue of interest in Higher Education. Various studies [1] have shown that students tend to get higher marks when assessed through coursework-based assessment methods which include either modules that are fully assessed through coursework or a mixture of coursework and examinations than assessed by examination alone. There are a large number of educational data mining (EDM) studies that pre-process data through conventional data mining processes including data preparation process, but they are using transcript data as they stand without looking at examination and coursework results weighting which could affect prediction accuracy. This paper proposes a different data preparation process through investigating more than 230,000 student records in order to prepare students’ marks based on the assessment methods of enrolled modules. The data have been processed through different stages in order to extract a categorical factor through which students’ module marks are refined during the data preparation process. The results of this work show that students’ final marks should not be isolated from the nature of the enrolled module’s assessment methods. They must rather be investigated thoroughly and considered during EDM’s data pre-processing phases. More generally, it is concluded that educational data should not be prepared in the same way as other data types due to differences as data sources, applications, and types of errors in them. Therefore, an attribute, coursework assessment ratio (CAR), is proposed to be used in order to take the different modules’ assessment methods into account while preparing student transcript data. The effect of CAR on prediction process using the random forest classification technique has been investigated. It is shown that considering CAR as an attribute increases the accuracy of predicting students’ second-year averages based on their first-year results.
Effects of Greenshipping to the Maritime Industry
Authors: Ogbonnaya E. A. , Poku R. , Adigio E.
Published: November 2020

In order to keep focus on the important agenda of sustainability which has lately become an issue of priority, the maritime industry must implement technologies on existing vessels and on those under construction so as to reduce their emissions into the environment. This study examines three potential sources of emission and also identifies a set of emission control measures that are available and could, if fully applied, reduce emission by 19.058%. With the waste heat recovery system, about 2500 kW of energy are saved, thereby increasing the efficiency to 59.11% having about 10.13% gain compared to engines without a waste heat recovery system. It is therefore recommended that the use of waste heat recovery systems should be encouraged on marine vessels to reduce the impact of noxious gasses into the atmosphere.
A Model-Based Approach of DC-DC Converters Dedicated to Controller Design Applications for Photovoltaic Generators
Authors: Labidi Z. R. , Schulte H. , Mami A.
Published: November 2020

In this paper, a model-based approach of DC-DC converters dedicated to controller design applications for photovoltaic generators is introduced. The paper provides a mathematic averaging model, based on the state space method for DC-DC converters that is used as an adaptation level in photovoltaic generators. This modeling allows the dynamics of the system to be described by presenting a reliable model to be used for oriented controller design. The two most needed topologies of DC-DC converters are proposed, buck and buck-boost, and an overview of integral state feedback controller design using a model-based approach for a boost converter connected to a photovoltaic generator described in our previous published work is provided. The model-based conception of both converter types is analyzed for optimal use in control-oriented design. The validation of each model is demonstrated by comparative curves represented by a detailed plant model using simscape devices available and implemented in Simulink/Matlab.
Hybrid PSO-Optimized ANFIS-Based Model to Improve Dynamic Voltage Stability
Authors: Truong D. N. , Bui V. T.
Published: November 2020

The objective of this paper is to perform a hybrid design for an Adaptive Neuro-Fuzzy Inference System (ANFIS) optimized by Particle Swarm Optimization (PSO) to improve the dynamic voltage stability of a grid-connected wind power system. An onshore 99.2MW wind farm using Doubly Fed Induction Generator (DFIG) is studied. To compensate the reactive power absorbed from the power grid of the wind farm, a Static VAR Compensator (SVC) is proposed. To demonstrate the performance of the proposed hybrid PSO–ANFIS controller, simulations of the voltage response in time-domain are performed in Matlab to evaluate the effectiveness of the designed controller. From the results, it can be concluded that the proposed hybrid PSO-optimized ANFIS-based model can be applied to enhance the dynamic voltage stability of the studied grid-connected wind power system.
Hydraulic Model Investigation on Stepped Spillway's Plain and Slotted Roller Bucket
Authors: Kote A. S. , Nangare P. B.
Published: November 2020

In ogee spillway, the released flood water from crest to toe possesses a high amount of kinetic energy causing scour and erosion on the spillway structure. The dam projects normally have a stilling basin as an energy dissipater which has specific energy dissipation limitations. The stepped spillway is a better option to minimize kinetic energy along the chute and safely discharge water in the river domain. The Khadakwasla dam is situated in Pune, Maharashtra (India), and has scouring and erosion issues on the chute of ogee spillway and on the stilling basin. The present study develops a physical hydraulic model for the dam spillway with steps, plain and slotted roller bucket as per IS Code 6934 (1998) and IS Code 7365 (2010). Experiments were performed at heads of 4m (low head) and 6m (high head) on the developed physical models, namely on the plain and slotted roller bucket model for the ogee spillway and the plain and slotted roller bucket model for the stepped spillway. It was found that the plain roller bucket of ogee spillway dissipates 81.26% of energy at the low head, whereas the stepped spillway with slotted roller bucket dissipates the 83.86% of the energy at the high head.
Analysis of Rectangular Plates on Resting Winkler and Two-Parameter Elastic Foundation Models by Finite Difference Method
Authors: Nguyen T. H.
Published: November 2020

Analysis of rectangular plates on a rising elastic foundation is common when designing the foundation of civil, traffic, and irrigation works. The current research presents the results of the analysis of rectangular plates on rising Winkler elastic and two-parameter foundation using the finite difference method. The computational programming was done on Matlab. The results of the research verify the accuracy of the FEM and are in agreement with findings in the literature. In addition, this research also compares the calculation results of two foundation models and investigates the change of plate height ratio to plate size.
Evaluation of the Mechanical Behavior of Local Brick Masonry in Pakistan
Authors: Shah T. M. , Kumar A. , Shah S. N. R. , Jhatial A. A. , Janwery M. H.
Published: November 2020

Masonry is the oldest form of construction in the world [1]. Research shows that it is the most widely used construction material in Pakistan and it has remained as such for more than the past hundred years. The majority of buildings in Pakistan are load-bearing burnt-brick masonry structures. Unfortunately, the brick masonry structures in Pakistan are not designed with respect to any regulatory code, because none exist. Consequently, these structures are not constructed according to a safe design and thus become hazardous and often face considerable damage and sometimes prove to be fatal. This study aims to study the behavior of local brick masonry under normal, shear and thermally challenging conditions and to model its behavior by relating the crushing strength (f’m) to the height-to-thickness ratio and temperature.
Utilizing Upper Arm Images in Determining Body Mass Index and Nutritional Status
Authors: Al-Mashaqbah S. F. , Al-Zyoud W. , Al-Zaben A.
Published: November 2020

Body mass index (BMI) is the most widely used index for determining the fitness status of an individual. Midd-upper arm circumference (MUAC) is another commonly used anthropometric index, providing a simple measurement widely used for nutrition level screening. However, building a massive population database based on both BMI and MUAC measurements is time-consuming and may introduce errors due to instrumentations and different operators. In this paper, a measurement technique of BMI from photographic images of the upper arm is presented. Three parameters are measured from the subject photos with a scale attached, and these are upper arm length, sagittal plane middle arm thickness (SMT), and frontal plane middle thickness (FMT). Different parameters are derived from the SMT and the FMT. These parameters are used to study the correlation and measurements agreements with the BMI. It is found that all parameters related to SMT correlate very well with the BMI with correlation coefficients of more than 90%. In addition, the SMT measurement limits (both upper and lower) are acceptable and within the clinical significance range. Finally, the receiver operating characteristics analysis of both SMT and MUAC has been evaluated. The findings show that SMT is slightly better than MUAC since it gives excellent sensitivity (94.7%) without compromising the specificity (88.5%) when compared to the MUAC results.
Dynamic Rock Type Characterization Using Artificial Neural Networks in Hamra Quartzites Reservoir: A Multidisciplinary Approach
Authors: Sokhal A. , Benaissa Z. , Ouadfeul S. A. , Boudella A.
Published: November 2020

A new multidisciplinary workflow is suggested to re-characterize the Hamra Quartzite (QH) formation using artificial neural networks. This approach involves core description, routine core analysis, special core analysis and raw logs of fourteen wells. An efficient electrofacies clustering neural network technology based on a self-organizing map is performed. The inputs in the model computation are: neutron porosity, gamma ray and bulk density logs. According to the self-organizing map results, the reservoir is composed of five electrofacies (EF1 to EF5): EF1, EF2 and EF3 with good reservoir quality, EF4 with moderate quality, and EF5 with bad quality. Hydraulic flow units are determined from well logs and core data using the flow zone indicator (FZI) approach and the multilayer perception (MLP) method. Obtained results indicate eight optimal hydraulic flow units. Hydraulic flow units for un-cored well are determined using the MLP, the used inputs to train the neural system are: neutron porosity, gamma ray, bulk density and predefined electrofacies. A dynamic rock typing is achieved using the FZI approach and combining special core data analysis to better characterize the hydraulic reservoir behavior. A best-fit relationship between water saturation and J-function is established and a good saturation match is obtained between capillary pressure and interpreted log results.
Greenhouse Modeling, Validation and Climate Control based on Fuzzy Logic
Authors: Jomaa M. , Abbes M. , Tadeo F. , Mami A.
Published: November 2020

This paper deals with the modeling and control of the air temperature and humidity in greenhouses. A physical model of the greenhouse used in the Simulink/Matlab environment is elaborated to simulate both temperature and indoor humidity. As a solution to the non-linearity and complexity of the greenhouse system, a fuzzy logic method is developed to control the actuators that are installed inside the greenhouse for heating, ventilation, humidification and cooling to obtain a suitable microclimate.
Identification of Building Failure Indicators
Authors: Khoso A. R. , Khan J. S. , Faiz R. U. , Akhund M. A. , Ahmed A. , Memon F.
Published: November 2020

A most frequent problem in the construction industry of Pakistan is the failure of structures, especially buildings, before their expected design life. Structural failure in buildings at the time of construction or after completion may result in human casualties, waste of money, social disturbance, and clashes, and claims between stakeholders. Many researches have already been conducted about key causes which lead a structure to fail at later stages. This research is pursuing to analyze early building failure indicators (BFIs) in Pakistan. Indicators and causes emerged from a thorough literature review, past projects, and site visits of various projects in Pakistan. The causes were grouped in sets of BFIs with the consent of structural experts. The collected data were analyzed in SPSS using mean value. Critical reasoning and conceivable recommendations are suggested by the opinion of experienced stakeholders having worked at various projects in Pakistan. The identification of these indicators is a key interest research topic for the country, as it would possibly reduce the failures of buildings in the future, saving lives, money, time, and conflicts among stakeholders.
Dynamic Economic/Environmental Dispatch Problem Considering Prohibited Operating Zones
Authors: Torchani A. , Boudjemline A. , Gasmi H. , Bouazzi Y. , Guesmi T.
Published: November 2020

Along with economic dispatch, emission dispatch has become a key problem under market conditions. Thus, the combination of the above problems in one problem called economic emission dispatch (EED) problem became inevitable. However, due to the dynamic nature of today’s network loads, it is required to schedule the thermal unit outputs in real-time according to the variation of power demands during a certain time period. Within this context, this paper presents an elitist technique, the second version of the non-dominated sorting genetic algorithm (NSAGII) for solving the dynamic economic emission dispatch (DEED) problem. Several equality and inequality constraints, such as valve point loading effects, ramp rate limits and prohibited operating zones (POZ), are taken into account. Therefore, the DEED problem is considered as a non-convex optimization problem with multiple local minima with higher-order non-linearities and discontinuities. A fuzzy-based membership function value assignment method is suggested to provide the best compromise solution from the Pareto front. The effectiveness of the proposed approach is verified on the standard power system with ten thermal units.
Crack Pattern Investigation in the Structural Members of a Framed Two-Floor Building due to Excavation-Induced Ground Movement
Authors: Mangi N. , Mangnejo D. A. , Karira H. , Kumar M. , Jhatial A. A. , Lakhair F. R.
Published: November 2020

Increased urbanization causes traffic and parking issues especially in metropolitan cities like Karachi, London, Shanghai, etc. To accommodate parking issues for the vehicles mainly in urban areas (excavated) underground parking areas under or nearby high rise buildings are preferred. As a result of excavation, ground movements occur that have a major impact on structures, buildings, and utilities. The past research usually oversimplified surface structure as an equivalent elastic beam, which is unable to represent the behavior of a framed building realistically. In this study, the detrimental effects (i.e. crack pattern) on a two-floor RCC framed building founded on piles due to an adjacent excavation-induced ground movement are investigated. Elasto-plastic coupled-consolidation analysis was adopted. The hypoplastic constitutive model was used to capture soil behavior. It is an advanced model which is able to capture the soil unique features which are non-linear behavior, stiffness degradation (with stress, strain & path-dependent), and stress-strain dependent soil dilatancy. The concrete damaged plasticity (CDP) model was used to capture the cracking behavior in the concrete beams, columns and piles. It was revealed that the induced slope and tilting are not equal. Consequently, the frame was distorted. As a result, tension cracks were induced at the inner side of the column.
Short-Term Electric Load Forecasting Using Standardized Load Profile (SLP) And Support Vector Regression (SVR)
Authors: Dung N. T. , Phuong N. T.
Published: November 2020

Short-term load forecasting (STLF) plays an important role in business strategy building, ensuring reliability and safe operation for any electrical system. There are many different methods used for short-term forecasts including regression models, time series, neural networks, expert systems, fuzzy logic, machine learning, and statistical algorithms. The practical requirement is to minimize forecast errors, avoid wastages, prevent shortages, and limit risks in the electricity market. This paper proposes a method of STLF by constructing a standardized load profile (SLP) based on the past electrical load data, utilizing Support Regression Vector (SVR) machine learning algorithm to improve the accuracy of short-term forecasting algorithms.
Analysis of Video Signal Transmission Through DWDM Network Based on a Quality Check Algorithm
Authors: Ilic S. , Jaksic B. , Petrovic M. , Markovic A. , Elcic V.
Published: November 2020

This paper provides an analysis of the multiplexed video signal transmission through the Dense Wavelength Division Multiplexing (DWDM) network based on a quality check algorithm, which determines where the interruption of the transmission quality starts. On the basis of this algorithm, simulations of transmission for specific values of fiber parameters ​​ are executed. The analysis of the results shows how the BER and Q-factor change depends on the length of the fiber, i.e. on the number of  amplifiers, and what kind of an effect the number of multiplexed channels and the flow rate per channel have on a transmited signals. Analysis of DWDM systems is performed in the software package OptiSystem 7.0,  which is designed for systems with flow rates of 2.5 Gb/s and 10 Gb/s per channel.
Clustering of Precipitation Pattern in Indonesia Using TRMM Satellite Data
Authors: Kuswanto H. , Setiawan D. , Sopaheluwakan A.
Published: November 2020

This paper identifies the climatic regions in Indonesia based on the rainfall pattern similarity using TRMM data. Indonesia is a tropical climate region with three main climate clusters, i.e. monsoonal, anti-monsoonal and semi-monsoonal. The clusters were formed by examining rainfall observation datasets recorded at a number of stations over Indonesia with coarse spatial resolution. Clustering based on higher resolution datasets is needed to characterize the rainfall pattern over remote areas with no stations. TRMM provides a high resolution gridded dataset. A statistical test has been applied to evaluate the significance of TRMM bias, and it indicated that the TRMM based satellite precipitation product is a reasonable choice to be used as an input to cluster regions in Indonesia based on the similarity of rainfall patterns. The clustering by Euclidean distance revealed that Indonesia can be grouped into three significantly different rainfall patterns. Compared to the existing references, there have been regions where the rainfall pattern has been shifted. The results in this research thus update the previously defined climate regions in Indonesia.
Automated Activity Recognition with Gait Positions Using Machine Learning Algorithms
Authors: Ng Y. L. , Jiang X. , Zhang Y. , Shin S. B. , Ning R.
Published: November 2020

Exoskeletons are wearable devices for enhancing human physical performance and for studying actions and movements. They are worn on the body for additional power and load-carrying capacity. Exoskeletons can be controlled using signals from the muscles. In recent years, gait analysis has attracted increasing attention from fields such as animation, athletic performance analysis, and robotics. Gait patterns are unique, and each individual has his or her own distinct gait pattern characteristics. Gait analysis can monitor activity in sensitive areas. This paper uses various machine learning algorithms to predict the activity of subjects using exoskeletons. Here, localization data from the UIC machine learning repository are used to recognize activities with gait positions. The study also compares five machine learning methods and examines their efficiency and accuracy in activity prediction for three different subjects. The results for the various machine learning methods along with efficiency and accuracy results are discussed.
Foreign Inclusions, Enclosed Cavities, Partial Discharge Models and Discharge Energy: A Short Review Regarding Solid Dielectrics and Composite Insulating Systems
Authors: Danikas M. , Morsalin S.
Published: November 2020

Partial discharges in cavities are one of the main reasons of breakdown of insulating materials and insulating systems in general. The present paper aims at commenting some aspects of the relation between partial discharges and insulation damage. Some basic models explaining the workings and impacts of discharges in cavities are discussed. Discussions about the possibility of damage in the presence of multiple cavities as well as of the risks of minute discharges and/or charging phenomena below the so-called inception voltage are conducted. It is remarked that the question of the relationship between discharge parameters and insulation damage is still an important one, especially for composite insulating systems.
Acceptable Wait Time Models at Transit Bus Stops
Authors: Arhin S. A. , Gatiba A. , Anderson M. , Manandhar B. , Ribbisso M.
Published: November 2020

This study aimed at determining patrons’ acceptable wait times beyond the bus scheduled arrival time at bus stops in Washington, DC and to develop accompanying prediction models to provide decision-makers with additional tools to improve patronage. The research primarily relied on a combination of manual and video-based data collection efforts. Manual field data collection was used for surveying patrons to obtain their suggested acceptable wait times at bus stops, while video-based data collection was used to obtain bus stop characteristics and operations. In all, 3,388 bus patrons at 71 selected bus stops were surveyed. Also, operational data for 2,070 bus arrival events on 226 routes were extracted via video playback. Data were collected for AM peak, PM peak and mid-day periods of nine-month duration from May 2018 through January 2019. The results of the survey showed that the minimum acceptable wait time beyond the scheduled arrival time was reported to be 1 minute, while the maximum acceptable wait time was reported to be 20 minutes. Regression analyses were conducted to develop models to predict the maximum acceptable wait time based on factors including temperature, presence of shelter at the bus stops, average headway of buses, and patrons’ knowledge of bus arrival times. The models were developed for A.M., P.M. and mid-day periods. The F-Statistics for the models were determined to be statistically significant with p values
Behavioral Modeling and Digital Predistortion of 2x2 MIMO Wireless Transmitters with Enhanced Multivariable Polynomials
Authors: Zemzemi I. , Boulejfen N.
Published: November 2020

In this paper we propose a novel concept named Enhanced Multivariable Memory Polynomials (EMVP) for the behavioral modeling and linearization of Multiple Input Multiple Output (MIMO) transmitters in the presence of linear (LC) and nonlinear (NLC) coupling effects. The proposed model improves the linearization performance of the conventional Multivariable Memory Polynomials (MVP) model. Its performance is experimentally compared with the ones of three popular polynomial models. EMVP model has succeeded in offering better linearization of MIMO transmitters, with fewer coefficients, compared to the conventional models. Experimental results showed improvement in Adjacent Channel Power Ratio (ACPR
Comparative Study of the Electrical Characteristics of Different Photovoltaic Modules in Outdoor Environment
Authors: Jatoi A. R. , Samo S. R. , Jakhrani A. Q.
Published: November 2020

The electrical characteristics of photovoltaic (PV) modules are affected by solar radiation and module temperature in outdoor environment. It was found that polycrystalline gained a yearly 0.50°C more average module temperature than monocrystalline. Non-crystalline amorphous modules got a yearly 0.83°C more average temperature than thin film modules. The attainment and release of module temperature was related with material properties of PV module technologies. The amorphous module gave 5.7%, 2.7% and 15.0% more yearly average open-circuit voltage than polycrystalline, monocrystalline and thin film modules. Besides that, the thin film modules gave 6.5% and 1.7%, 9.3% and 4.0%, and 11.3% and 8.8% more yearly average normalized short-circuit current and power output than polycrystalline, monocrystalline and thin film modules respectively. It was shown that the maximum annual average open-circuit voltage was given by amorphous modules and maximum short-circuit current and power output by thin film modules during the study period.
Intelligent Control of a Photovoltaic Pumping System
Authors: Elgharbi A. , Mezghani D. , Mami A.
Published: November 2020

This paper presents the application of the Adaptive Neuro Fuzzy Inference System (ANFIS) to track the maximum power of a photovoltaic generator that feeds a motor-pump group unit through a Pulse Width Modulation (PWM) inverter powered by a Single Ended Primary Inductance Converter (SEPIC) installed in the laboratory. The ANFIS control is trained in different temperatures and irradiances and the maximum power point tracking system varies automatically the duty cycle of the SEPIC converter. The performance of the MPPT controller is tested in simulations in Matlab/Simulink.
Experimental Water Quality Analysis from the Use of High Sulfuric Fly Ash as Base Course Material for Road Building
Authors: Viet Duc N.
Published: November 2020

Water quality directly influences human life. Drinking water contamination can result in severe health problems. This paper deals with the analysis of water specimens from submergence of material containing high sulfuric fly ash as base course material for road building. The specimens were obtained from real road testing. Results showed that for the material that used fly ash and chemical admixture, water quality was suitable for drinking in accordance with the standard parameters prescribed by the Vietnam Ministry of Health, while for the material that used the same fly ash without chemical admixture, the total arsenic content was eight times higher than that of the former. Thus, if one desires to utilize fly ash with high sulfur as base course material for road building, it needs to be used in combination with appropriate chemical admixture, so that it would not affect ground water quality.
Particle Packing Application for Improvement in the Properties of Compressed Stabilized Earth Blocks with Reduced Clay and Silt
Authors: Malkanthi S. N. , Perera A. A. D. A. J.
Published: November 2020

Soil as a building material has been used in different forms such as mud, adobe, rammed earth and bricks. The present study focuses on producing Compressed Stabilized Earth Blocks (CSEBs) giving attention to the particle size distribution in the soil mixture. The literature established that compressive strength significantly depends on clay and silt content and 25% of clay and silt produce optimum results while no attention has been given to the amount of other, larger particles. Soil grading refers to the combination of different-size particles in a soil mixture. The correct selection of sizes in the correct proportion may cause improvements in CSEB properties. This paper explains the application of particle packing technology for the improvement of CSEB properties. The theoretical concepts provide a continuous particle size distribution, and the soil used for the experiments also has a continuous particle size distribution. The soil used in the experiments was subjected to washing to reduce the clay and silt content. Separated clay and silt and large particles of different sizes were added to the mixture to match particle size distribution to the optimization curves as explained in particle packing theories. The experimental results show that the CSEB properties can be significantly improved by modifying particle size distribution to fit the suggested optimization curves. According to the results, the compressive strength improved by more than 50% with different amounts of cement stabilization. Significant improvements in the dry densities and water absorption ratios of blocks were observed with this particle size modification.
The Influence of Coconut Fiber on the Compressive and Flexural Strength of Paving Blocks
Authors: Mudiyono R. , Sudarno S.
Published: November 2020

The aim of this study is to determine the influence of coconut coir fiber on the compressive and flexural strength of paving blocks. The research was carried out using paving blocks with dimensions of 20cm×10cm×6cm, mixed with coir fiber by 0%, 0.1%, 0.2%, and 0.3% by weight. The results showed that no addition of coconut coir fiber resulted in compressive strength of 24.49Mpa, while the addition of 0.1% coconut coir fiber resulted in compressive strength of 25.39Mpa after 7 days. A mixture with no coconut coir fiber resulted in flexural strength of 31.5Mpa while the addition of 0.1% coconut coir fiber gave a flexural strength of 33Mpa in the age of 14 days. The conclusion of this study is that the addition of 0.1% coconut coir fiber in a paving block mixture can increase its compressive and flexural strength.
Flexural Behavior of RC Beams Made with Recycled Aggregates Under 12-Month Long Term Loading
Authors: Oad M. , Memon B. A. , Buller A. H. , Memon N. A.
Published: November 2020

In the present era of infrastructure development, demolishing waste management poses serious problems, particularly in urban centers. Vast development requires huge amounts of conventional concrete aggregates resulting in serious environmental problems. Therefore, efforts are carried out in utilizing demolishing waste, particularly demolishing concrete as coarse aggregates used in new concrete. This article presents laboratory investigations of flexural behavior of reinforced concrete beams made with partial replacement of natural coarse aggregates with coarse aggregates from demolished concrete under 12-month long-term loading. Two batches of beams were cast and cured for 28 days. In the first batch three RC beams with partial replacement of natural coarse aggregates were cast, while in the second batch 6 RC beams with all-natural coarse aggregates were prepared. Out of these six beams three beams were tested under short-term loading to determine maximum load. 50% of this load was used as sustained load on the remaining all beams. The beams were mounted on purpose made frames and deflection, strain, and cracking were recorded on daily basis. After the elapse of the defined time the beams were tested under central point load until failure. Result comparison shows a 4.96% increase in deflection and 2.33% reduction in peak load. Based on the results of this study it is concluded that demolished concrete as coarse aggregates in new concrete shows reasonably good performance under 12-month long-term loading.
Corrosivity Evaluation of Copper-Nickel Alloy (90/10) in Pumps Used in Offshore Platforms for Seawater Pumping
Authors: Mainier F. B. , Coelho A. M. , Barros E. F.
Published: November 2020

This work discusses the case of corrosion in a copper-nickel alloy used in seawater, where chlorination is necessary to control micro- and macro-organism growth that can render inoperable the seawater supply system used in an offshore platform. Studies developed in the last 30 years have shown copper-nickel’s adequateness in seawater, with a corrosion rate of about 0.001mm/year. However, annual equipment inspection showed localized corrosion in an internal chamber in a stand-by pump. Such corrosion occurred due to high-concentration of sodium hypochlorite (NaClO) injection into the operational system, even for pumps that were out of operation. To evaluate this corrosive process, gravimetric (mass loss) and electrochemical tests were developed in synthetic seawater with NaClO at concentrations of 100, 500, 1000 and 5000mg/L. The results indicated that the corrosiveness varied from low to moderate. The presence of pitting and crevices observed in the laboratory tests derails or compromises material use in seawater. It was concluded that there is a need for continuous monitoring of the NaClO injection in seawater pumps, and a method was proposed in order to minimize or avoid a high concentration of chlorine in standby pumps.
Influence of Coarse Aggregate Gradation on the Mechnical Properties of Concrete, Part II: No-Fines Vs. Ordinary Concrete
Authors: Buller A. S. , Tunio Z. A. , Abro F. U. R. , Ali T. , Jamali K. A.
Published: November 2020

This study aims to investigate the effect of different gradations of coarse aggregates on mechanical properties of no-fines concrete (NFC). NFC reduces a structure’s self-weight, thus minimizing cost. The effects of coarse aggregate gradation on mechanical properties such as compressive strength, split tensile strength, and flexural strength were studied and compared at the end of 28-day water curing. A fixed cement- to-aggregate proportion 1:6 with 0.5 water/cement (w/c) ratio was adopted. Four gradations of coarse aggregates ranging between specific maximum and minimum size were used, namely 5mm-4mm, 10mm-4mm, 20mm-4mm and 20mm-15mm. The results of this study reveal the substantial effect of the gradation of coarse aggregates on strength properties compressive and tensile strength of NFC.
Suitability of Quaternary Sediments of Wadi Arar, Saudi Arabia, as Construction Materials: An Environmental Radioactivity Approach
Authors: Alghamdi M. A. M.
Published: November 2020

The surficial quaternary deposits of Wadi Arar were radioactively evaluated for construction purposes. The concentrations of 226Ra, 232Th, and 40K were used to evaluate the radioactive suitability of Wadi Arar. Gamma-spectrometry technique with an HPGe detector was used to measure the concentrations of Ra, Th, and K. The average specific activities of Ra, Th, and K were 22.92, 16.99, and 223.66Bq/kg respectively. The average value of the air absorbed dose rate (D) was 30.47nGy/h. The average values of the indoor and outdoor annual effective dose equivalent (AEDE) were 149.46 and 37.36μSv/y respectively. The average value of the radium equivalent activity index (Raeq) was 64.44Bq/kg. The maximum values of the external and internal hazard index (H) were 0.20 and 0.27 respectively. Radioactivity concentration and hazard index values are within the acceptable global values and do not pose any significant radiological threat to the population. These results reflect the safety of Wadi Arar as a site for construction and the potential to use depositional sediments at the site as construction materials.
Post Construction and Long Term Settlement of an Embankment Dam Computed with Two Constitutive Models
Authors: Bhutto A. H. , Zardari S. , Bhurgri G. S. , Zardari M. A. , Bhanbhro R. , Memon B. A.
Published: November 2020

For the settlement computation of an embankment dam, the soil stiffness is of great importance. Unfortunately, due to the lack of funds allocated for geotechnical investigation, stiffness parameters are commonly not evaluated as compared to strength properties. As a result, this may create hindrance in the use of advanced constitutive models such as Hardening Soil Model (HSM). In this study, the settlement with respect to depth and long term settlement of an embankment dam computed with Mohr-Coulomb Model (MCM) is compared with that of HSM applied to foundation soil only with limited data on stiffness. The results show that the MCM overestimated settlement in comparison with HSM. The settlement increment of MCM, in comparison with HSM, at the crest and at the depth of 120m was 53% and 82% respectively after the filling of the reservoir. The settlement computed with MCM and HSM were 2.9% and 1.35% of the dam height. It can be interpreted that the settlement predicted with MCM is unrealistically high due to the single constant value of modulus of elasticity (MOE), while the predictions of HSM are in agreement with the literature. In addition, the long term settlement computed using MCM is about 59% higher than that of HSM for the condition after the filling of the reservoir. This paper shows that the settlement of an embankment dam could be predicted reliably by using HSM even when a limited number of stiffness data is available.
Spectral Re-Growth Suppression in the FBMC-OQAM Signal Under the Non-linear Behavior of a Power Amplifier
Authors: Jake J. , Mwangi E. , Langat K.
Published: November 2020

Typically, the filter bank multicarrier with offset quadrature amplitude modulation (FBMC-OQAM) bears some impressive properties that make it popular as one of the substitutes to orthogonal frequency division multiplexing (OFDM) for the upcoming technology of broadband wireless communication systems. Although FBMC-OQAM preserves the multicarrier modulation (MCM) features, its spectrum usually suffers from impairments when subjected to the nonlinear behavior of a power amplifier (PA) which results in spectral re-growth. Due to the spectrum limitation and low energy efficiency foreseen in the forthcoming 5G networks, it is vital to confine the spectrum of the FBMC-OQAM signal within the allocated band of interest. In this paper, the suppression of the spectral re-growth experienced on the FBMC-OQAM signal due to the nonlinear distortion effects introduced by the PA is investigated. The crest factor reduction (CFR) method in combination with an adaptive digital pre-distortion (DPD) are used. The peak windowing technique based on sequential asymmetric superposition windowing (SASW) algorithm is used in the CFR part while the least square estimation with QR-decomposition (LSE/QR) has been used as the coefficient’s estimator and adaptation algorithm in the DPD part. The performance of the two combined techniques has been evaluated on SystemVue2018 simulation platform. The adjacent channel leakage ratio (ACLR) and the error vector magnitude (EVM) have been considered as the performance merits. The simulation results show that the proposed techniques significantly improve the spectrum, first by reducing the PAPR of the FBMC-OQAM signal by about 1.5dB. Secondly, the spectral re-growth has been reduced by about -45.74dB adjacent channel leakage suppression and the error vector magnitude measure has been obtained to be about 7.12%. (-22.95dB). These values lead to better average input power of the FBMC-OQAM signal and improvement in the spectral efficiency and they are in accordance with the 3GPP standard for wideband signals in nonlinear systems.
Application of FVSI, Lmn and CPF Techniques for Proper Positioning of FACTS Devices and SCIG Wind Turbine Integrated to a Distributed Network for Voltage Stability Enhancement
Authors: Eisa Osman S. H. , Irungu G. K. , Murage D. K.
Published: November 2020

Induction power generators are the most popular wind energy conversion systems (WECS) because they do not require synchronization units. However, they usually draw a huge quantity of reactive power during disturbances. Hence, incorporating wind power into power networks may cause voltage instability. This paper presents the usage of STATCOM and SSSC FACTS devices for voltage stability enhancement of a distribution network with a squirrel cage induction generator (SCIG) wind power turbine. The continuation power flow (CPF) approach is utilized as a tool to determine the most suitable position of SCIG in the system. Also, voltage stability indices (FVSI and Lmn) are employed to estimate the stability margin of the system by figuring the weakest transmission lines and buses in order to locate the appropriate position where the FACTS devices should be installed. A comparison of the suitability of the FACTS devices to restore system stability was evaluated under 3-phase fault conditions. The results illustrated that STATCOM behaves better than SSSC when the system is restoring from a fault. Simulations and voltage stability assessment were carried out on the IEEE 14 bus test scheme using the PSAT simulation software package.
Serviceability of Reinforced Concrete Gable Roof Beams with Openings under Static Loads
Authors: Hassan M. A. J. , Izzet A. F.
Published: November 2020

This paper presents an analytical study on the serviceability of reinforced concrete gable roof beams with openings of different sizes, based on an experimental study which includes 13 concrete gable roof beams with openings under static loading. For deflection and crack widths under static loading at service stage, a developed unified calculation procedure has been submitted, which includes prismatic beams with one opening subjected to flexure concentrated force. The deflection has been calculated with two methods: the first method calculated deflections via relevant equations and the second was Direct Stiffness Method in which the beam is treated as a structural member with several segments constituting the portions with solid sections and those with sections crossed by the opening. The crack width was calculated with the ACI code’s equation with a proposed magnification factor equal to 1.125. The analytical results were compared with the experimental ones and a good agreement was obtained.
Unscented Kalman Filter based State of Charge Estimation for the Equalization of Lithium-ion Batteries on Electrical Vehicles
Authors: Muratoglu Y. , Alkaya A.
Published: November 2020

Accurate state of charge estimation and robust cell equalization are vital in optimizing the battery management system and improving energy management in electric vehicles. In this paper, the passive balance control based equalization scheme is proposed using a combined dynamic battery model and the unscented Kalman filter based state of charge estimation. The lithium-ion battery is modeled with a 2nd order Thevenin equivalent circuit. The combined dynamic model of the lithium-ion battery, where the model parameters are estimated depending on the state of charge, and the unscented Kalman filter based state of charge, are used to improve the performance of the passive balance control based equalization. The experimental results verified the superiority of the combined dynamic battery model and the unscented Kalman filter algorithm with very tight error bounds. Furthermore, these results showed that the presented passive balance control based equalization scheme is suitable for the equalization of series-connected lithium-ion batteries.
Voltage Enhancement on DFIG Based Wind Farm Terminal During Grid Faults
Authors: Chung P. D.
Published: November 2020

This paper proposes a method of retaining high enough voltage on the terminal of DFIG wind turbines during a fault interval on the connected grid. This method is developed by the ideal of dynamic voltage restorer equipment and was applied to a wind turbines group. The DC-link and the grid side converter of the first DFIG wind turbine in this group are utilized to support the other wind turbines. The converter is connected to a transformer, which is in series with the wind turbine group and the connected line, during an external fault. At the DC-link of the back-to-back converter of each DFIG wind turbine, a DC chopper is equipped to dissipate excessive active power during the fault interval. Moreover, the controllers of all wind turbines are modified to support all wind turbines in the group. The method is verified by MATLAB/Simulink. Simulation results implied that the proposed method can retain a high enough voltage on the terminal of DFIG while preventing overcurrent on the rotor side.
Numerical Simulation of Damage on Warm Deep Drawing of Al 6061-T6 Aluminium Alloy
Authors: Rajhi W.
Published: November 2020

This work focuses on the numerical simulation of warm deep drawing operation of car sump oil made with Al 6061-T6 aluminum alloy for the purpose of process optimization. The thermo visco-plastic behavior with damage effect of the material is described by the Johnson-Cook (JC) model. The JC model parameters for the Al 6061-T6 Aluminum alloy were exploited. Numerical simulation of the deep drawing operation was performed with the use of the ABAQUS FE software thanks to the dynamic Explicit Temperature-Displacement algorithm. The design of the different tools is obtained on the basis of the geometry of the finished product. Designing of punch, die and blank holder is performed using CATIA 3D CAD software. The warm forming method involves the heating of the blank holder and the die to a certain temperature, whereas, the punch is kept at room temperature. In this study, predefined temperatures of the die and blank holder and punch speed will be investigated among other stamping parameters. The computed damage evolution curves for a given set of the process parameters are retrieved at the end of the simulation to determine suitable forming conditions. It can be noted that the slower the damage evolution achieved within the blank, the more appropriate the process parameters. Thus, by increasing strain rate, main cracks change location.