bluuebunny/crossref_metadata_2025 huggingface dataset:
A mechanical property evaluation of Ti6Al4V cellular lattice structures fabricated by selective laser melting
Authors: Azir M Z , Harun W S W , Kadirgama K
Published: June 2020

Cellular structures are similarly identified as lattice structures or foam structures which are commonly constructed of ligaments. Cellular structures exist widely in nature, such as the coral, honeycomb, and the natural bones. Cellular structures are also manufactured and used in various applications such as honeycomb bumper structures and truss bridge. Ti6Al4V is one of the most commonly used titanium alloy and is applied in a wide range of application where low density very good corrosion resistance are necessary such as direct manufacturing of part and prototypes for racing and aerospace industry, biomechanical application such as implants and prosthesis, marine application, chemical industry, and gas turbine. This paper investigates the mechanical properties of Ti6Al4V lattice structures fabricated by additive manufacturing, also known as 3D printing. The samples are fabricated by selective laser melting (SLM) using titanium alloy (TI6Al4V). Four factors were selected to determine its influence on the Young’s modulus and compressive strength, which is strut size, strut shape, unit cell size, and porosity. All the samples categorize to six groups by its design volume porosity obtained from CAD file. Solidwork design software was used in this study. The influence was shown in a comparison graph. Detailed characterizations of compression test were conducted and reported. The built structures have a Young’s modulus ranging between 0.01 and 1.84 Gpa. Porosity was realized to play an important role in determining the Young’s modulus and compressive strength.
Detection of irregularities on weld bead from the L-Statistic analysis of the acquired sound during pulse mode laser welding process
Authors: Yusof M F M , Ishak M , Ghazali M F
Published: June 2020

Since several past decades, many studies prove that the statistical or signal features extracted from the sound acquired from laser welding process was significantly giving information on the weld condition. However, a considerable amount of studies were only emphasizing on the use of common statistical features in which it is restricted to some limitation when dealing with non-stationary random sound signal. In this particular work, the main aim was set to detect the irregularities along the weld bead by way of implementing the L-Statistic analysis on the acquired sound during pulse mode laser welding process. To achieve the goal, pulse mode laser welding have been done onto 22MnB5 boron steel plate in butt joined configuration. During the process, sound signal was acquired using microphone and further analyzed by extracting L-statistic features from it. According to the findings, among all the L-statistic features analyze in this study, L-Cv (scale) was found giving a significant indicator of the weld bead surface condition. Larger value of L-Cv was recorded at the point where the large underfill occurred. On the other hand, it was also found that the L-kurtosis values could give remarkable information on the existence of the irregularities on bead width and depth. Hence, it could be drawn into conclusion that the irregularities on the weld bead during the pulse mode laser welding could be detected from the appropriate L-statistic features of the acquired sound signal. The finding in this work was believed to be essential in enhancing the capability of acoustic sound method to be developed as online monitoring system for pulse mode laser welding process.
Friction and wear characteristic of natural bone for water hydraulic: A computational analysis
Authors: Hamdi Zakuan , Ayuni Suhaimi Fatin , Ismail M A , Jefri A S , Samsuri S. I. , Januddi Fatihhi
Published: June 2020

Instead of mineral oil, water hydraulic uses seawater or tap water as the medium in its operation. Most of the materials tested have some reaction towards friction and water lubrication. While hydraulic system may be advantaged by natural materials, the related work remains unestablished. In present work, the tribology of bone in contact with stainless steel is computationally simulated. The materials combination used in this study were metals (316L stainless steel and Al2O3) and natural bone. Increase in contact pressure is found to be contributed by the extent of sliding distance. Wear depth is also subsequently increased in this manner. Higher normal load applied on the model exhibits higher contact pressure in between metal-bone pair model.
Model comparison of estimated glomerular filtration rate for acute kidney injury in intensive care unit
Authors: Dzaharudin F , Jamaludin U K , Ralib A M , Mat Nor M B , Tumian A , Ismail A R
Published: June 2020

Acute kidney injury (AKI) is common in critically ill patients and often associated with higher mortality. It is commonly diagnosed using plasma creatinine, a fluid excreted by glomerular filtration. In this study, we analysed the highly nonlinear and complex behaviour within human systems of estimating glomerular filtration rate in critically ill patients to estimate AKI outcome by developing an application program that describes various numerical mathematical models estimated glomerular filtration rate (eGFR). The program was developed to collect numerous clinical patient data and perform computations of the governing equations that may provide clinicians with rapid estimation of GFR which allow prediction of recovery or worsening of renal function at bedside. Data collection using the application program was conducted at the intensive care unit in Kuantan, Malaysia from January to August 2016. It was found that the eGFR by CKD-EPI shows the best correlation with kinetic GFR (keGFR) equations compared to other mathematical methods for Malaysian ICU patients. It is endeavoured that more patient data would be collected using this mobile application, to develop a more accurate GFR estimation model suitable for Asian populations since creatinine based equations are often derived based on white populations.
Development of wrist monitoring device to measure wrist range of motion
Authors: Jin Hiung Fong , Mat Sahat Idris
Published: June 2020

Study of human motion has been paying attention. From manual goniometer which consists of moving arm and a protector to assess the range of motion had been developed into equipment with strain gauge, flex sensor and many more. In recent years, the advance of microelectromechanical systems (MEMS) has boosted the use of inertia measurement unit (IMU). MPU 6050 is one of the IMU used in this study to assess wrist range of motion. Algorithm using Arduino has developed to improve the accuracy. A Bluetooth module is used to communicate with smartphone. An android application is developed to display data on smartphone. The device is tested to validate the reliability of measuring wrist range of motion. First test is carried out to test for the stability of each axis at 300, 600 and 900. For roll axis (counter-clockwise) and pitch axis (counter-clockwise) shows fluctuation. The other axis show slightly fluctuation. When tested on human wrist, the device able to give error in the range of 10 – 50. The result from device is compared with manual goniometer performed by physiotherapist. Placement of device o back of hand may affect the result. Front spot, middle spot and end spot placement has been tested to see the relationship. From testing, middle spot and end spot show better result compare to front spot. In performing radial deviation and ulnar deviation, end spot show significant closer result. However, this placement restricts the movement of wrist. Middle spot give overall close result.
Influence of dip-coating times towards oxygen separation performance
Authors: Sazali Norazlianie , Syafiq Sharip Mohd , Ibrahim Haziqatulhanis , Shahir Jamaludin Ahmad , Norharyati Wan Salleh Wan
Published: June 2020

Several advantages possessed by carbon membrane such as can be easily processed, high gas separation performance and requires adequate amount of energy compared to the conventional separation process are the reasons it is deemed as the future media of separation. This study utilized PI blends and nanocrystalline cellulose (NCC) to prepare the tubular carbon membrane in order to investigate its fabrication. The effect of dip-coating duration (15, 30, 45, and 60 min) on physicochemical properties O2/N2 separation was determined. Carbonization was done at 800 °C with 3 °C/min rate of heating under argon gas flow (200 mL/min). Tests of pure gas permeation were conducted in order to study the transport mechanism of prepared carbon membrane at ambient temperature and 8 bar of feed pressure. Carbon membrane with O2 permeance of 29.92 ± 1.44 GPU and O2/N2 selectivity of 9.29 ± 2.54 were obtained after 45 min of dip coating.
Processing and characterization of natural Bentonite from Aceh, Indonesia as filler of Poly-Caprolactone/Poly-Lactic Acid/Chitosan, (PCL/PLA/Chitosan) nanocomposites
Authors: Ridwan  , Wirjosentono B , Tamrin T , Rihayat T , Nurhanifa
Published: June 2020

The formation of composite from polymer mixture PCL / PLA / Chitosan bentonite was carried out through the melt intercalation method using an extruder at 180 °C with a holding time of 20 minutes. Bentonite is obtained from Kab. North Aceh which has been modified with CTAB surfactant. The sample formulations used were single PCL and PCL polymers each given 3, 5 and 8 % chitosan fillers. A mixture of PCL / PLA (50: 50) was given 3, 5 and 8 % chitosan / bentonite fillers. The sample is a white plastic rod (bone) material which is tested for its nature through several types of characterization. Modified bentonite and chitosan have an effect on increasing the mechanical and thermal properties of PCL, PLA and mixture polymers both based on the results of tensile test, TGA test (thermal) and bacterial test. PCL / PLA 50:50 with the addition of 8 % bentonite-chitosan filler is the most perfect composition which provides the best test value.
Analysis of boundary condition in modelling the low-velocity impact carbon-fiber reinforced polymer composite laminates
Authors: Meon M S , Saedon J B , Nor N H , Rao M N , Schröder K-U
Published: June 2020

The effect of modelling strategy on boundary condition and impact energy of low-velocity impact laminate has been investigated. The paper deals with the finite element model (FEM) to study the structural responses of carbon fibre reinforced polymer (CFRP) composite laminate of CCF300/epoxy. In FE calculation, a proposed three-dimensional progressive damage model is used to determine the intralaminar damage, while cohesive contact formulation is employed to analyse the interlaminar damage. The failure model performances are validated and verified based on different boundary conditions and impact energies. Through experiment and simulation, it can be said that variation in boundary condition as well as impact energy, significantly change the force-time, displacement-time, energy-time, and load-displacement histories.
Bio-Nanocomposite Polyurethane / Clay / Chitosan Paints that have thermal resistance and antibacterial properties for biomedical applications
Authors: Rihayat T , Suryani  , Riskina S , Siregar J P , Jaafar J , Cionita T , Fitria
Published: June 2020

The coating material used for the manufacture of polyurethane paints is a coating of hybrid organic-inorganic materials based on palm oil (oleic acid). Polyols are produced from the synthesis of oleic acid by adding organic and inorganic ingredients. Chitosan and bentonite are organic and inorganic elements, which are used to improve thermal capability and antibacterial properties of polyurethane paint produced. Hybrid bentonite-chitosan is then synthesized with polyols and isocyanate is added, namely TDI (Toluene Diisocyanate) to form polyurethane. In the FTIR spectrum of the polyol on O-H bond at Wavelength 3210.25 cm-1, C-H bond at Wavelength 2856.87 cm-1 and C = O bond at Wavelength 1610.86 cm-1, and hybrid bentonitechitosan of FTIR Analysis Chitosan: -OH group at Wavelength 3250 cm-1, N-H at 3545 cm-1, C = O at wavelength 1681 cm-1, C-H group at Wavelength 2810 cm-1. Bentonite: -OH group at Wavelength 3435 cm-1, Si-O group at Wavelength of 1161 cm-1 and Al-O and Si-O groups at Wavelength 820 cm-1. Aliphatic C-H Cluster at 2815 cm-1 Wavelength and 1125 cm-1 Wavelength indicates the presence of a C-O group. While the results of SEM (Scanning Electron Microscope) from polyurethane products and with the addition of hybrid bentonite-chitosan namely polyurethane paints produced mixed with chemicals and the main ingredients are polyols from palm oil (oleic acid) while small white clumps greyish namely hybrid bentonite-chitosan which has been mixed into polyurethane paint. This study produced a hybrid material of benthicchitosan as a filler in the manufacture of polyurethane paint.
Compressive properties on the spherical-roof contoured-core cell with different amounts of diamond-shaped notches
Authors: Quanjin Ma , Rejab M.R.M. , Idris M.S. , Merzuki M.N.M. , Shaoliang Huang
Published: June 2020

It is a challenging task to develop lightweight materials and novel structures, which offers better energy-absorbing characteristics. Therefore, it is still a significant issue to obtain secondary processing on available contoured-cores to provide a lightweight structure. This paper is aimed to investigate the effect of compressive properties on the single spherical-roof contoured-core cell with series diamond-shaped notches subjected to quasi-static compressive loading, which is referential concept on second weight reduction. The spherical-roof contoured-core panel was manufactured using a compression moulding process, and then cut to every single cell followed the diamond-shaped notch mould. It is concluded that with the number of diamond-shaped notches increasing, compressive strength and modulus generally shows the decreasing trend. Energy absorption, specific energy absorption, and peak load are also studied. In addition, the failure types of single cell units are discussed according to corresponding experimental results. It is highlighted that diamond-shaped notch cutting fabrication of core structure is a sufficient method to reduce the load concentration at the spherical-roof apex.
Review of Phononic crystals and acoustic metamaterials
Authors: Chen Qiqi , Zhang Bo , Bai Yutian , Wang Liheng , Rejab M R M
Published: June 2020

As a new type of acoustic functional material, phononic crystal has great research value and application environment. It is a periodic structure of two or more elastic materials, which are derived from photonic crystals. The main research work on phononic crystals focuses on the two band gap formation mechanisms of Bragg scattering and local resonance, and some new methods of vibration reduction and noise reduction can be obtained by studying its banding mechanism. Similarly, a “metamaterial” has been proposed for the ability to achieve new vibration reduction and noise reduction, which is a composite structure or material with physical properties not available in natural materials. By analysing the acoustic metamaterials of various structures, in this work we can understand how to achieve vibration reduction and noise reduction under the local resonance mechanism.
Study on sound absorption properties of fiber materials and perforated components and their composite structures with different structural parameters
Authors: Fu Qiang , Zhang Bo , Bai Yutian , Wang Liheng , Rejab M R M
Published: June 2020

Fiber materials and perforated components are often used as basic structural units, which are widely used in the field of environmental noise reduction and automotive noise reduction.In this work, the effects of different structural parameters on the sound absorption properties of fiber materials, perforated components and their composite structures are studied. The sound absorption coefficients of fiber materials, perforated elements and their composite structures with different structural parameters were simulated by COMSOL finite element software. The transfer function method is used to measure the sound absorption in the impedance tube. The simulation results are in good agreement with the experimental results. The results show that the thickness of sound absorption material has a great influence on the sound absorption coefficient. The perforation rate is an important factor affecting the sound absorption performance of perforated components. When the perforation rate is high, it hardly absorbs sound. With the increase of aperture and wall thickness, the sound absorption performance increases in low frequency band and decreases in medium and high frequency bands. The non-periodic oscillation of sound absorption coefficient occurs with the change of cavity thickness.
Effect of heat treatment conditions on mechanical properties and springback of 6061 Aluminum alloy sheets
Authors: Wang Guan , Zhu Guangxu , Li Ting , Kou Linyuan
Published: June 2020

The mechanical properties and bending deformation behaviors of homogenization treated (HT), solution treated (ST), natural aging (NA) treated and T6 6061 aluminum alloy sheets were investigated by tensile tests and three-point bending tests, respectively. The results showed that the heat treatment conditions have a significant impact on mechanical properties and bending characteristic. Bending radius and thickness of the HT alloy is the highest, and its springback angle is the lowest. However, the deformation mechanism of T6-8h alloy is just the opposite. The bending characteristics are attributed to the combined effects of yield strength, strain-hardening exponent and coefficient of the neutral layer. The simulation results are in good agreement with the experiment.
Effect of through-holes on quasi-static axial compression behaviors of aluminum with thin-walled structure
Authors: Wang Guan , Li Wang , Xue Lian , Kou Linyuan
Published: June 2020

The effect of through-holes position on deformation behaviors and energy absorption of 6063 aluminum alloy with thin-walled structure, taking the same number and different positions of through-holes, will be investigated by quasi-static axial compression using universal testing machine. The experimental results show that the compression behavior of thin-walled structure specimens can be significantly improved by properly opening through-holes and selecting appropriate locations. Based on the experimental data, the fluctuation degree of sample load was reduced. The stability of compression deformation was improved. The first peak load was reduced. And the energy absorption performance of the specimens was improved.
Single hole direct injector simulation validation and parametric sensitivity study
Authors: Hafidzul Rahman Alias Mohamad , Fadzil Abdul Rahim Mohd , Abu Bakar Rosli
Published: June 2020

This paper presents a parametric study conducted on electronically controlled solenoid direct fuel injector running on compressed natural gas. The purpose of the study is to identify the influential injector parameters on the output fuel mass flow rate. These injector parameters are to be optimize in the next stage of the study. The parametric study is conducted using zero-dimensional, first principle injector model which consist of electro-magnetic, mechanical and flow sub-models. In current study, seven (six input and one output) selected parameters have been analysed which are the injection pressure, injection duration, nozzle diameter, armature mass, the input voltage, spring constant and the output mass flow rate. Each input parameters are varied in the prescribed range based on the literature. Based on the study, the most influential parameters (in rank) are the nozzle diameter, the armature mass and the injection duration. The input voltage, the injection pressure and the spring constant were found to have no impact on the injector mass flow rate based on the values of parameter’s sensitivities. Based on the results, the potential parameters to be optimized are identified.
Techno-economic feasibility of Palm Fatty Acid Distillate (PFAD) blend as alternative to diesel fuel
Authors: Mantari M H A R , Hassim H M , Rahman R A , Zin A F M , Yahya M S , Samiran N A , Asmuin N
Published: June 2020

Palm oil had been as fuel in Malaysia with implementation of petroleum diesel and Palm Methyl Ester (PME) blend at 5% in 2014 and mandatory 10% blend in 2019. The high cost of the feedstock is the major drawback of PME. Not only PME comes from expensive low Free Fatty Acid (FFA) feedstock, the cost to convert FFA to PME through the process of transesterification and purification of palm oil fatty acid also expensive. Another feedstock for palm based biofuel is palm fatty acid distillate (PFAD). PFAD is a by-product of crude palm oil (CPO) refining. It is inedible and cheaper compared with other palm oil product thus attractive as a feedstock for biofuel. Five blends of PFAD and diesel with 5%, 10%, 15%, 20% and 25% were produce in this study. The blending was done using magnetic stirrer and was mix continuously for 30 minutes at 60 ∼. The properties of the blends such as density, viscosity, surface tension, pour point and calorific value were determined experimentally. Result from these experiments showed that density, viscosity, surface tension and pour point were increase proportionately when PFAD content increase except for calorific value. The calorific value showed minor reduction with maximum reduction at 3% as compared with diesel fuel. This happen when the PFAD content was at 25% blend. In term of availability of PFAD as biofuel source, data from year of 2016 to 2019 showed that the amount of PFAD produce in Malaysia suffice to support 5% blends of PFAD as biofuel.
Computational fluid dynamic modelling of NOx formation in diesel engine
Authors: Hoseini S S , Najafi G , Ghobadian B , Azimi-Nejadian H , Ahmadian Hossein
Published: June 2020

The purpose of this study is offering a numerical model to predict the NOx formation of a diesel engine. For this purpose, simulation of combustion and emissions of a diesel engine was performed using CFD FIRE commercial software. The simulation was performed for the condition of 900 rpm for engine speed, 200 bar cylinder pressure, and injection timing (15° CA BTDC). The difference between the experimental and numerical results was reported by about 3.2%. The result of the numerical simulation shown due to the non-homogeneous mixture of air and fuel in a diesel engine, the temperature distribution is not uniform and the temperature in some places reaches 2500 K. In areas with an equilibrium ratio (stoichiometry) and temperatures above 2000 K, nitrogen oxide is the highest. Also, the result shown areas with a temperature range between 1500 and 1900 K are more favorable areas for the formation of soot pollutant.
Experimental study of a mini cooler by using Peltier thermoelectric cell
Authors: Fairuz Remeli Muhammad , Ezzah Bakaruddin Nurfarah , Shawal Syahar , Husin Hazran , Fauzi Othman Muhammad , Singh Baljit
Published: June 2020

A 20 x 26 x 18 mm mini thermoelectric Peltier cooler was designed and built in this study. The Peltier thermoelectric cell was sandwiched between an external and internal heat sinks that acted to remove heat from the cooler box. When the Peltier thermoelectric cell connected to an external power source, the Peltier effect caused the heat from the refrigerator internal space to be conducted and removed to the ambient. The experimental data from this study were used to validate the theoretical thermal resistance model. It was found that the Peltier cooler was able to produce COP higher than 0.5 which the output was quite high compared to previous studies. This cooler was able to lower cooler box temperature down to 18.5 °C from the ambient temperature by removing 25W of heat. In the future, the validated theoretical model could be used to estimate the suitable design parameter such as the type of heat sinks, the size of the cooler, the cooling temperature and the cooler performance including the coefficient of performance (COP).
The analysis of wind blade on the performance of Vertical Axis Wind Turbine
Authors: Kong Johan Kong Nurziana , Abu Bakar Rosli , Yi Leang Lim , Adnin Hamidi Mohd
Published: June 2020

The long-term energy crisis is one of the biggest issues of this century that needs to be tackled to ensure a prosperous future for coming generations and wind energy is one of the energy sources that grows rapidly and most promising renewable energy. Vertical Axis Wind Turbine (VAWT) is the best option for small wind turbine project and suitable for low average wind speed environment. In this project, experiment had been carried out to study the effect of wind blade number on the Savonius wind turbine performance at different wind speeds and a comparison had been made to choose the best performance between 2, 3, 4, 5 and 6 blades wind turbine. A small Savonius wind turbine prototype, PicoScope, Digital Anemometer, Digital Tachometer and other equipment were used for this purpose. A PicoScope software with a hardware device had been used to create an oscilloscope and spectrum analyser on the PC. The experiment was carried out in an open room space to acquire a close condition to the real environment. The performance results were analysed and Malaysia’s average wind speed had been used as the guideline for the comparison. It can be deduced that 5 blades rotor gives the best performance compared to the 2, 3, 4 and 6 blades rotor. At wind speed 6.1 m/s, 5 blades rotor produced optimum mechanical power output at 260 mW, power coefficient of 0.109 (10.9 %), torque at 0.12 mN.m and tip speed ratio at 8.28.
A study of base isolation system at cyclotron building in Indonesia High Seismic Region
Authors: Hyundianto  , Wahyu N
Published: June 2020

The study of earthquake resistance design on cyclotron bunkers using base isolators was introduced. With the increasing trend of detection and treatment of cancer using nuclear technology in Indonesia, the construction of nuclear medicine facilities which include the manufacture of radiopharmaceuticals using a cyclotron facility must be held immediately. With the many areas in Indonesia in earthquake-prone areas, a cyclotron bunker design is needed that can accommodate the effects of the earthquake. The cyclotron bunker must be able to withstand earthquake loads without damage because apart from being a building structure, concrete also acts as shielding radiation during cyclotron operations. Base isolators have become a reliable technology in overcoming earthquake loads and will be used in cyclotron buildings in earthquake areas. By using the spectrum response method in the cyclotron building, the results of the base isolator will be evaluated. It was found that building acceleration after adding base isolators decreased 37% and base isolators also increased the vibration period of cyclotron bunkers away from the earthquake period.
Design of BeiDou-based data acquisition system for oil and gas wells in remote areas
Authors: Hu Sheng , Jiang Le Kai , Bo Shi Wen
Published: June 2020

The real-time operation status monitoring of natural gas wells in the wilderness area has problem such as construction suffering, high maintenance cost, and high data transmission cost. In view of the above problems, this paper studies the design of a multi-node data transmission system using Beidou satellite short message as the data transmission means. Firstly, analysed the advantages and disadvantages of several common data transmission methods and introduced the Beidou short message; Secondly, introduced the main working parameters of the oil and gas well; Thirdly, The data acquisition and transmission system was designed in detail and the prototype system was developed. The experimental results show that the data transmission success rate of the system can reach more than 98%. This system solution can provide a useful reference for engineering with similar requirements.
Characterization of brushed dc motor with brush fault using thermal assessment
Authors: Wahab A A , Rasid M A H
Published: June 2020

Direct current motors (DC motor) are used in the small electric devices commonly. Brushed DC motors are cheap and easy to install, thus their popularity. Although the popularity, faults occur which make diagnosis and detection of faults very important. It avoids financial loss and unexpected shutdown operation causes by these faults. This paper is a present characterization of brushed DC motor with brush fault using thermal signature analysis. To organize the character, the temperature profile of DC motor was analysed using the K-type thermocouple with data logger. The thermocouples were mounted on 4 part of the DC motor, casing, permanent magnet, brush and bearing. The temperature data of DC motor with faulty brush and healthy DC motor were measured by thermocouple and recorded using data logger in real time until steady state temperature, under different load. The analysis on the steady state temperature of brush fault can be conclude through recognisable of characteristics temperature difference with a healthy motor.
Reducing heat losses – first step toward nZEB
Authors: Boian I , Tuns I
Published: June 2020

Energy consumption for space heating and air conditioning holds a significant share in the total energy consumption, among them residential and tertiary buildings being on the first places. This strong energetic dissipative character of different elements of the building envelope offers multiple possibilities of intervention aiming to reduce the heat losses. The Romanian requirements concerning the elements evaluating conformity with the Standard C107-2010 and the Order no.2641/2017 are given with a focus on thermal bridges influence aside with a short description of different ways to estimate this influence in EU countries. The paper presents in general, concepts to be used in order to achieve the nZEB standard developed by the Energy Performance of Building Directive having in mind a mitigation of greenhouse gases, GHG emission. In this context, is presented the role of balcony elements as undesirable “heat exchanger” and this thermal bridge is depicted together with some ways to avoid this inconvenience.
Influence of link length on re-centring capability of dual eccentrically braced frames
Authors: Chesoan A , Stratan A , Dubină D
Published: June 2020

Repair costs and downtime of a structure hit by an earthquake can be reduced, by implementing the concepts of removable dissipative members (bolted links which are intended to provide the energy dissipation capacity and to be easily replaceable) and re-centring capability (which is provided by the more flexible moment resisting frames) in a dual structure, obtained by combining steel eccentrically braced frames (EBFs) with removable bolted links, with moment resisting frames (MRFs). The seismic performance, re-centring capability and link replacement feasibility of a dual re-centring EBF with removable flush end-plate bolted links were already studied and experimentally validated. In this case, very short shear links were used in order to achieve the flush end-plate connection over-strength, so the connection can be kept elastic in order to make the link removal possible. Re-centring capability of EBFs with other types of removable links has not been yet approached. One of the main objectives of an ongoing research project is to extend the validation of re-centring capability and link replacement feasibility on extended end-plate bolted links. This type of connection geometry provides a larger connection capacity, thus shear links can be designed longer. The present paper numerically investigates the influence of using different link lengths (and connection detailing) on the recentring capability of two height levels structures.
The impact of thermal rehabilitation of the reinforced concrete water tanks Romanian built fund over its lifecycle
Authors: Covatariu D , Filip A , Covatariu G
Published: June 2020

Liquid storage tanks are special structures and strategically very important. In particular, water tanks are important to assure a continued operation of water distribution system in the event of unpredicted events. In order to ensure the operating conditions in normal parameters, the temperature of the stored liquid (drinking water) have to not exceed certain limits. The aim of this article is to investigate the most suitable thermal insulation system for a reinforced concrete overground water tank. In this regard, a comparative multicriteria analysis has been performed presenting the main advantages / disadvantages of each material (extruded polystyrene, basaltic mineral wool, organic ecological foam) taking into account several criteria. The scores obtained have been compared in order to highlight the most effective material in the case of the reinforced concrete water tanks.
Numerical methods to find the slope at a point on map using level curves. Application in road designing
Authors: Deaconu O , Deaconu A
Published: June 2020

The problem of determining the slope at a point on a map using level curves has practical applicability in designing the roads. This problem is reduced to the problem of finding the shortest length segment through a point that connects two coplanar lines. Two methods to solve this problem are presented: a fast approximate method and a slower but exact algorithmic method. The results are compared at the end.
Considerations about fire behaviour of an unprotected wood elements according to Romanian Code SR EN 1995-1-2-2004
Authors: Erbaşu R , Țăpuşi D
Published: June 2020

Increased interest in wood as construction material has led to the development of research on improving physical and mechanical characteristics of different wood species or various types of processed wood. Since wood construction materials are combustible, it is necessary to improve their fire behavior. This is achieved by treating the surface or the mass of materials using flame retardant substances, which can delay the ignition and can reduce the speed of propagation of fire. Although its benefits: specific weight, thermal conductivity, chemical stability, good vibration and shock absorption, good dimensional stability against temperature, ease of processing, etc., wood has the great disadvantage that it will ignite easily, being a cellulosic material.
Investigations regarding the degradation state of a Romanian country road
Authors: Hoha D , Țăranu N , Ungureanu D , Boboc V , Isopescu D N , Pleșcan E-L , Boboc A , Scutaru M C , Domnița L I
Published: June 2020

This study is aimed to identify and to describe some of the most common types of pavement degradations that may develop on some Romanian county roads. According to the road safety management system, The County Direction of Road and Bridge Administration has the responsibility to ensure the traffic conditions, by preventing or repairing any degradation that may have adverse effects on the ride’s safety and comfort. The most common types of degradations that can be identified on the Romanian county roads are: block cracks, longitudinal / transverse cracks, joint stepping, rocking, joint sealant defects and local declines. The process of interventions for restoring the road safety condition is continuous and span through the entire lifecycle of the structure (planning, design, build, operate, maintain and decommission). In order to illustrate the degradation state and to identify the most appropriate type of intervention required to restore the road safety condition, a case study is presented. The latter consists in a county road located in the Northern part of Romania (Suceava County), designated with the route number DJ 177A. The viability of the road was evaluated based on visual inspections and laboratory testing of its component materials. Based on the experimentally results several intervention works were suggested.
Study on regional applicability of dehumidification air conditioning system with different stage regeneration modes
Authors: Hao H , Zhang Y D , Xin P
Published: June 2020

This article also put forward staged-regeneration wheel of the air conditioning system with condensing heat recovery technology, according to the climate zones in China, using the DesT software simulation in different areas of thermal and moisture load in a villa, and regeneration of the runner desiccant air conditioning system performance calculation, the results show that the compared with the two area runner desiccant air conditioning system, hierarchical regeneration runner desiccant air conditioning system performance are improved, the system of the refrigerant mass flow is reduced, the cooling load of the evaporator is reduced, the total load also significantly reduce energy consumption, air conditioning systems exergy efficiency improved; For regions with low temperature, low humidity or moderate humidity, the desiccant air conditioning system of three-areas graded regeneration wheel is more energy saving. In temperature and humidity relatively moderate areas, classification of renewable energy saving effect of the wheel were similar, but the four-areas wheel exergy efficiency obviously is higher than other wheel; For regions where both temperature and humidity are relatively high, the energy saving of the air conditioning system of the rotary wheel in the three-areas is not obvious, and the energy saving effect of the two-stage rotary wheel is the most significant.
Dynamic characteristics of CLT panels: computer modelling and simulations
Authors: Kozarić L , Vojnić Purčar M , Tekic Z , Bešević M , Zivković S
Published: June 2020

The fundamental vibration frequency and deflections due to the unit static force of the cross-laminated timber panels of different heights and spans were calculated. The calculation of the effective flexural rigidity was performed by the Gamma method. Obtained values are compared with the values obtained by modeling the construction in the Ansys software package. Three types of floor panels were analyzed with the same combinations of layer thicknesses in the cross section, but with different number of layers. The panels are 4, 5 and 6 meters long and 1 meter wide. Based on the results, recommendations have been made in accordance with current criteria that define the acceptable behavior of lightweight floor structures in relation to vibrations caused by human action.
Contributions to the consolidation of wooden floors to structures with load-bearing masonry walls
Authors: Lapuste A V , Mociran H A
Published: June 2020

The consolidation of wooden floors is a common intervention in the practice of building rehabilitation. The necessity of this type of works comes from the sensitivity of wood to biological degradation, the existence of a significant number of heritage buildings in which the construction of the slabs was done without ensuring compliance with the requirements of the normal exploitation (limiting the deformations), the occurrence in operation of the need to increase the capable loads. It is required, in case of consolidation at earthquake of the buildings with wooden floors, the creation of rigid slab (rigid in horizontal plane). The consolidation solutions that can be adopted are different, trying to respond to the diversity of situations/particularities which are encountered in practice. The paper briefly reviews the solutions currently used for the rehabilitation of wooden floors, then presenting a solution for the consolidation of a wooden floor belonging to an intermediate floor acted by gravitational actions, respectively a solution for achieving the rigid slab of an attic, of a multi-storey building.
Researches on energy conversion of municipal waste by plasma decomposition for energy-efficiency in civil engineering
Authors: Lupu M L , Isopescu D N , Cucoş I , Antonescu I , Maxineasa S G , Baciu I-R
Published: June 2020

This paper presents the research, technologies and testing equipment developed for the energy plasma conversion of municipal waste in order to enhance energy-efficiency in the civil engineering domain. The purpose of this work is the environmentally friendly improving the efficiency of waste conversion processes by using controlled plasma decomposition reactors developed by the authors, which generate syngas, electrical and thermal energy which can be used in civil engineering.
Effectiveness of tuned mass dampers for improved seismic performance of dual eccentrically braced steel frames
Authors: Mociran H A , Lăpuște A V
Published: June 2020

Tuned mass dampers (TMDs) have been widely used for the control of seismic response of various new or existing buildings, successfully. However, the use of TMDs in the case of dual eccentrically braced steel frame structures has not been found in the technical literature. The paper appraises numerically the efficiency of TMDs in enhancing the seismic response of dual eccentrically braced steel frame structures and investigates the influence of mass of the TMD on the level of the response reduction achieved. To achieve these goals, a typical mid-rise five story steel frame structure with perimeter dual eccentrically braced frames, located in Bucharest, has been considered. Then, bidirectional TMDs with three mass ratios 0.04, 0.06 and 0.08 have been added on the top floor of the building, without redesign the frame members. Comparative nonlinear time history analyses of the unequipped and equipped structure have been performed with accelerograms of Vrancea 1977 type. Numerical results (peak base shears, peak inter-story drifts ratio and peak absolute story accelerations) show the efficiency of TMDs in mitigating the seismic response of dual eccentrically braced steel frames.
Multicriterial optimization of topo-geodetic techniques for behaviour monitoring in service stage of civil engineering structures
Authors: Morariu D-I , Lepădatu D , Șerbănoiu I
Published: June 2020

Optimization of civil engineering systems is a complex process that includes both theoretical and practical knowledge of experts from different disciplines. Optimization is defined as a rigorous process by which the methods corresponding to an engineering problem are analyzed and selected. The objective of this scientific paper is to define an optimal system / technique in monitoring the behaviour of civil engineering structures by topographic methods using the multi-criterial decision theory, by analyzing, combining and comparing some topographic methods and techniques used in monitoring the behavior of objectives by identifying decisional criteria (quantitative and qualitative) and applying one-or multi-criteria decisions. Finally, by choosing quantitative and qualitative criteria, we can establish the optimal techniques that correspond to the monitoring activity of the behaviour in service stage of civil engineering structures. The necessity for this optimal system that uses an algorithm is to reduce the risks and uncertainties that may arise from the monitoring process of buildings. Also, the results obtained must fulfil a certain accuracy, time and cost conditions, as well as their extent for other monitoring activities in topographical measurements.
Assessment of code-based design approach of buckling restrained braced frames in P100-1/2013 using pushover analysis
Authors: Mosnoi E , Stratan A , Voica T F
Published: June 2020

Buckling restrained braced frames (BRBFs) are a relatively new structural system, characterized by high seismic energy dissipation. The Romanian seismic design code P100-1/2013 has recently introduced design provisions for buckling restrained braced frames. According to the code, the dissipative components are designed for the seismic forces reduced by behavior factor q, while the non-dissipative components are capacity-designed for seismic forces amplified with an over-strength factor Ω
T
. The objective is to assess the code-based capacity design procedure using the nonlinear static analysis. Three structural configurations are considered: two BRBF configurations and a dual BRBF configuration. The structures are first designed following the code procedure, and then analyzed using a pushover analysis, using a numerical model of the buckling restrained braces calibrated on experimental data.
Approach, understanding, needs and integration of the BIM concept in the Romanian modern society
Authors: Muntean R , Chițonu G C , Radu D , Cazacu C E , Gălățanu T
Published: June 2020

The aim of this study is to look at the level of knowledge about BIM (Building Information Modelling) in 3 important constructions sectors: higher education institutions (HEI) - companies – public bodies. In reference to the studies and surveys made in Romania by a team from Transilvania University of Brasov, in the frame of an Erasmus+ research project - UrbanBIM, it is reasonable to hypothesize that most of the people surveyed did not understand what BIM really is, and some were unable to identify the differences between BIM and CAD (Computer-aided design). Making population surveys and analysing the data allow for determining the methodologies for future implementation of BIM technologies and improving the educational training. The concept understating shows the preponderance of using BIM technology in the construction sector, developed on extended levels, starting from urban planning, geographic information system (GIS), architecture, engineering and construction (AEC), building management and leading to life cycle analysis (LCA) and energy efficiency (EE).
Freeze-thaw testing of stabilized soil samples used for riverbank consolidation
Authors: Nagy A-Cs , Cîrcu A-P , Ciubotaru V-C , Crăciunescu B M , Topan G , Moldovan D V , Moldovan L-E , Pașca D M
Published: June 2020

Riverbank erosion is a common problem of the Romanian freshwater system. Classic riverbank stabilization methods consisted of using different type of concrete, however concrete manufacture consumes large amount of non-renewable raw materials and energy, and it is a carbon-intensive process. Many efforts are, therefore, being undertaken towards the developing “greener” solutions. There are different type of retaining walls resulted from the need to avoid reinforced concrete wall solutions, such as gabion walls, solid masonry walls, rocky embankment prisms, and wooden pile retaining systems. But all of these solutions converge on gathering raw material from an external source, and transporting it on location. In Romania acquiring crushed stone tends to become problematic, especially, in the areas outside the Carpathian mountain range. Therefore a solution of using local soil as a base for a stabilized soil layer is very practical and economical from a technologic point of view. Being a hydrotechnical application, the freeze-thaw resistance of the stabilized layer is crucial for the lifetime of structures. The objective of our study was to determine this parameter, in accordance with the Romanian norms and regulations.
Current approaches regarding the assessment of quality of the buildings from the perspective of the user’s perception
Authors: Parincu P D
Published: June 2020

The article focuses on the satisfaction of the users/beneficiaries and on the quality level of the construction industry. Monitoring user satisfaction brings benefits in the construction industry by improving communication between the parties, engaging in mutual agreements, evaluating progress and monitoring the results and changes made. Users have certain claims about how they want to be treated, moreover, the physical product obtained must fit within their internal value system.