bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Calibration and Error Analysis of Dual-Axis Tracking Trough Solar Collector System
Authors: Deng Jian Ling , Zhu Yong , Zhou Zi Li , Zhai Rong Rong , Song Ji Feng , Yang Yong Ping
Published: October 2014

In this paper, a dual-axis tracking trough solar collector system is established, and used to measure and calibrate flow rate at different conditions by using the ultrasonic flow meter and mass flow meter, providing important reference for follow-up experimental study. With the changing of the medium’s temperature and the rotation speed variation of the pump, the two flow meters were used to work together to measure the accurate flow measurements, obtaining the measurement error of the mass flow meter. After that, the reason of error and methods used to reduce the error are analyzed.
Manufacturing the Renewable Fuel of Butanol by Adsorption Separation Processes with the Novel Starch Sorbent
Authors: Chung Tsair Wang , Wahyu Di Na , Hsu Shih Hong
Published: October 2014

Bio-based butanol has superior properties when compared to ethanol to be the gasohol and is gradually considered to be an important biofuel from the biomass fermentation of ABE solution. The potential sorbents for acetone (A), 1-butanol (B), and ethanol (E) recovery process will be analyzed by the isotherm data and the sorbents, such as potato starch sorbent and ZSM-5 will be selected. The above sorbents to adsorb acetone, 1-butanol, and ethanol for single-component adsorption using adsorption equilibrium apparatus will be conducted and the isotherm data will be obtained.
Research on Semi-Empirical Model for Backscattering Coefficient of Sea Clutter
Authors: Wu Geng Kun , Ji Guang Rong , Ren Hong Xia
Published: October 2014

To understand the influence of sea clutter on radar target detection, this paper simulates three typical backscattering coefficient models, i.e. GIT, TSC and HYB. Also, it proposes a new approach to evaluate the fitting degree between TSM and the three backscattering coefficient models. Finally, this paper gives the applicability of different models in the calculation of electromagnetic scattering.
Study on Drying Characteristics of Masson Pine Deresination Wood
Authors: Qiao Jian Zheng
Published: October 2014

In order to find the more suitable drying schedule, this test, by adopting 100°Cdrying test method, studies the index of drying characteristics of Masson pine deresination wood, examines and evaluates the drying quality grade indexes. Based on the results, a drying schedule reference was drawn up.
Dark Environment Motion Analysis Using Scalable Model and Vector Angle Technique
Authors: Yong Ching Yee , Sudirman Rubita , Chew Kim Mey
Published: October 2014

Detecting human existence in video streams is a fundamental task in many video processing applications. In this paper, a novel procedure is produced to model, analyze and recognize human motions (jogging and walking in dark environment) in video streams. There are four major areas that are related in this project for human motion analysis: (1) developing human body structure based on human skeleton model, (2) tracking and data collecting human motion with side view, (3) recognizing human activities from image sequences, and (4) image processing technique using edge detection and vectors angle calculation. All algorithms are developed using MATLAB software. Segmentation is developed to reduce the amount of data and filters out the useless information. Two methods are proposed for angle calculation and activities classification. Results showed that angle between 153.76°-180° for method 1 and 49.64°-92.86° for method 2 is classified as walking while jogging is 95.17°-138.72° for method 1 and 22.62°-56.31° for method 2.
Propagation Environment Analysis and Wireless Mesh Network Implementation for Monitoring the Four Rivers (Based Dalsung Weir)
Authors: Yun Yo Bal , Hong Sung Taek , Yang Youn Goo
Published: October 2014

It is necessary to monitor a variety of observing data in river areas among dozens to hundreds of kilometer for safe river administration. The 20th construction area of the four river project is located on Dalsung areas, where wireless mesh network was installed to manage the basin. In the process of network construction, the characteristic of surrounding areas is considered about embodying secure service by investing the least expense.
Structural Synthesis of Parallel Linkages by Multibody Systems Method
Authors: Visa Ion , Neagoe Mircea , Moldovan Macedon , Comsit Mihai
Published: October 2014

A large variety of methods are mentioned in literature for the structural analysis and conception of parallel linkages, applicable to planar and/or spatial mechanisms developed for various applications as manipulators-robots, guiding mechanisms for car wheels and axle, solar tracking systems. Modern design requires today a unitary description of all the mechanisms in a product (including linkages) for complex simulation and optimization on software platforms. This paper proposes a seven steps general method for the parallel linkages’ structural analysis and synthesis, considered as Multibody Systems. The method is based on the concept that describes a mechanism by a minimum number of bodies. Using as input data the application area, the motion space, the mechanism mobility and the type of joints, all possible fundamental multibody chains are obtained and, based on, the corresponding mechanisms. The method is described in detail and applied for the geometrical constraints of rotational (R), spherical (S), translational (T) and their combinations types. As example, a tracking system for a solar thermal platform, based on a parallel linkage with two degrees of freedom with R, S and T joints is presented.
Fatigue Analysis of Large Diameter Threaded Connections Subjected to Dynamic Axial Loads
Authors: Cojocaru Vasile , Miclosina Calin Octavian , Korka Zoltan Iosif
Published: October 2014

The large diameter threaded connections are components with high importance in the heavy mechanical systems. At the threaded elements subjected to variable loads one of the main causes of failure is represented by fatigue. This phenomenon is accentuated by the occurrence of high local stresses on the thread root. In this context, the correct evaluation of the local stresses and their correlation with the fatigue behaviour has a major importance in the correct assessment of remaining life of large diameter threaded connections.The paper is focused on the finite element analysis of the large diameter threaded bolts with two types of threads profiles: trapezoidal and square. For the two types of threads the simulations were performed using four nominal diameter and two different loading setups. The bolts were summited to static analysis in order to determine the local stresses distribution in the threaded area. The maximum values of Von Mises stresses obtained in the static analysis were exported to fatigue studies. The differences between the results obtained for the two types of threads are outlined.
The Influence of the Fatigue Cycles Number on Material Hardness
Authors: Goanta Viorel
Published: October 2014

In this paper we present the experimental results obtained after determining hardness on samples previously subjected to fatigue. Firstly, 6 identical samples have been subjected to stress fatigue in the elastic range a number of 105, 5∙105, 106, 2∙106, 3∙106 and 4∙106 cycles. For all samples we used the same form of stress cycle, respectively, sinusoidal, and the same values of maximum, minimum force and the amplitude of the cycle (50 kN, 30 kN and 10 kN). It is noted that the maximum value of the load was less than that at which samples fall within the plastic deformation. Therefore, the original loading of samples was performed in the elastic range. For each of the six samples determinations of levels of hardness were performed, with the value of indentation load of 10 kgf. Indentations were made on the samples, along the length of the calibration, at a distance of 10 mm one within the other. As it will be seen below, in the areas with the highest hardness were performed several indentations, in order to determine the highest hardness area, which, in our view, also presents the largest degree of plastic deformation.
Residual Stresses in Cylindrical Roller Bearings – A Three-Dimensional Analysis Model
Authors: Popescu Gabriel
Published: October 2014

The author presents an accurate method to calculate the residual fields in case of non-hertzian elastic-plastic contact problems in roller bearings. This kind of analysis requires a complete three-dimensional investigation due to the finite length of the contacting bodies. Previous analyses carried out in two-dimensional case are not able to take into account the complexity of the problem and the so-called edge-effect that is known to reduce the bearing fatigue life. A semi-analytical code previously developed was adapted to account for three-dimensional line contact analysis. A non-linear rate independent isotropic and kinematic hardening model is implemented for the bearing steel plastic behavior. Closed form solutions for residual stresses during cyclic non-proportional loading are obtained from the plastic strains and they are considered as initial stresses at every loading cycle.
Design of Experimental Test Bench for Determining the Stresses and Strains State of Guitar Neck
Authors: Stanciu Mariana Domnica , Curtu Ioan , Mihalache Daniel
Published: October 2014

Bending causes of neck guitar, with negative economic effects are: technology - deviations from flatness, straightness, produced during processes due to faulty adjustment of machine tools, structure / material – the wood used in guitar structure leads to deformations that exceed the terms of rigidity due to anisotropy, mechanical - occurrence rheological phenomena (wood relaxation after being subjected to stresses during machining), physical - wood moisture, humidity and ambient temperature. Bending of guitar neck occurs either after completion of manufacturing processes when the guitar is not used (case I), or after a storage period without it being stressed (case II) and after a period of use (case III). The paper presents the concept of experimental stand and a set of procedures for measuring deformations of guitar neck obtained during the bending stress in three points (Figure 1). The criteria in the design of test bench were: providing mechanical boundary conditions to simulate real conditions; ensuring mobility measuring apparatus and data recording so that it can be investigated all the structural elements of the guitar; ensure stability of the tabs and the whole stand in order to avoid measurement errors; ensure handling and maintenance of subassemblies by using ergonomic dimensions, optimum materials and interchangeable parts.
Deployable Structures for Architectural Applications - A Short Review
Authors: Doroftei Ioan , Doroftei Ioan Alexandru
Published: October 2014

Deployable structures can provide a change in the geometric morphology of the envelope by contributing to making it adaptable to changing external climate factors, in order to improve the indoor climate performance of the building. They have the ability to transform themselves from a small, closed or stowed configuration to a much larger, open or deployed configuration being also known as erectable, expandable, extendible, developable or unfurlable structures. According to their structural system, deployable structures can be devided in four main groups: spatial bar structures consisting of hinged bars, foldable plate structures consisting of hinged plates, strut-cable (tensegrity) structures and membrane structures. In this paper a short review only on two of these groups of deployable structures for arhitectural applications will be presented.
Rolling Bearings Greases Deterioration: Structure, Chemical Composition, Rheology, Service Life Correlations
Authors: Farcas Flavian , Tiron Mihail Catalin
Published: October 2014

Grease lubrication for ball or roller bearings became a daily practice in technical applications (over than 80% of bearings assemblies can be greased lubricated) because of its advantages in avoiding the sophisticated circulation or cooling systems.In the same time, all the researches that were developed in this field are lack in informations regarding the forming and the deterioration of grease lubricated contacts.The global results of the researches on the lubricating greases are presented. The tests were done in different functioning conditions and media and for greases analyses chemical and imagistic methods were performed. The discovered correlations are very useful in obtaining as long as possible greased rolling bearings service life.
The Influence of Substrate on the Mechanical and Tribological Characteristics of MEMS Materials for Space Applications
Authors: Merie Violeta , Pustan Marius , Birleanu Corina , Negrea Gavril
Published: October 2014

Aluminum, gold, silver, nickel, silicon, glass, silicon dioxide, silicon nitride and so on, employed as bulk materials or thin films, represent the most commonly used materials for MEMS applications within the automotive, biomedicine, spatial industries and so forth. This work is a study regarding the influence of substrate nature on the mechanical properties of silver thin films elaborated for MEMS devices. The silver thin films were obtained by thermal evaporation method under vacuum protection on three different substrates. Glass, plastic (polycarbonate) and steel (C45) respectively are the materials used for the substrates. Further, atomic force microscopy investigations were performed on the elaborated samples in order to characterize them at a nanoscale and establish substrates influence. The Young’s modulus, nanohardness and roughness of the researched samples are the characteristics that were determined. A significant influence of substrate nature on the properties mentioned above for the studied silver thin films was marked out.
Wear Model of Sliding Motion Flat Surfaces Used in Mechanical Engineering
Authors: Petre Ivona
Published: October 2014

Wear is defined as the process of destruction of the shallow layer of a coupling in a small volume of material, that leads to the wear particle occurence. The mechanism of wear particle formation depends to a great extent on the strain state in the contact area (elastic, plastic, elasto-plastic), on the nature of the material (breaking tenssion, flowing tenssion etc) and on the working conditions (pressure, velocity, temperature etc). The harder material, function on the maximum strain on the friction surface, function on the angle and the geometry of roughness (or abrasive particles) may be elastically or plastically distorted, thus changing the state of the conjugate surface.The paper proposes an answer mode analysis of the materials of a friction coupling with sliding motion, for materials with different hardness.
Stress Study of Removable Partial Denture with Attachments Using Finite Element Analysis
Authors: Andrei Oana Cella , Tanasescu Livia Alice , Margarit Ruxandra , Tierean Mircea Horia
Published: October 2014

The paper presents the study of the stresses and the displacements that appear in different areas of the removable partial denture (RPD) with extracoronal attachments under occlusal loading, using FEA. The first step was to create the 3D model of a RPD with ball attachments in case of a class I Kennedy edentulous patient with all six anterior teeth as abutments. All materials were considered homogeneous, isotropic and having linear elasticity. There were assumed two types of constraints: in the first one the model is fixed under the action of the mastication forces; in the second one the rotational movement of the denture’s saddles in the sagittal plane was simulated, towards the edentulous ridge. In the first case, the 3D model and FEA were developed using Autodesk Inventor 2013 software. In the second case, the FEA was done using Autodesk Algor Simulation software. The loading of the model was symmetrically applied, considering the magnitude of the tangential and normal oral forces determined by Las Casas et al. These forces were applied to all the PM1, PM2, M1 and M2 pairs. Each loading case was analysed separately. The results of the two constrain situations are presented graphically, comparatively and show that the amount of the saddle displacement depends on the application area of the mastication force. Maximum displacement was computed at the application of the mastication forces on the M2 and decreases as the force is applied more mesial. The amount of the major connector’s deformation is very little influenced by the site of the force. The largest displacement of the denture was recorded at the distal end of the saddle, with values ​​that depend on the site of the forces. The existence of the rotational movement of the denture’s free end saddles in the sagittal plane, towards the edentulous ridge, changes the values ​​of accumulated stresses in denture during mastication and its Von Mises stress peaks. This analysis can be use to establish the principles of planning and designing the RPD with ball attachments having in mind to minimize the number of repairs caused by fractures of the components.
Modeling of the Seated Human Body in a Vibrational Medium
Authors: Barbu Daniela Mariana
Published: October 2014

Vibrations are mechanical oscillations produced by regular or irregular period movements of a member or body about its rest position. Vibration can affect visual perception, muscles, concentration, circulation and the respiratory system and at certain levels can even result in physical harm to the body. The effect of vibration on the human body is related to the natural frequency of parts of the human body affected. This paper studies the dynamic characteristics of a seated human body system in a vibration environment. The main result is a multi degrees of freedom lumped parameter model. The model provided an analytical tool for human body dynamics research. It also enabled a primary tool for seat and cushioning design. Combining the geometry and the mechanical characteristics of a structure under large deformation into a lumped parameter model enables successful analysis of the human/seat interface system and provides practical results for body protection in dynamic environment. The relative displacements of human parts are evaluated, which can be a basis for the assessment of vibration risk. It is suggested that the multi-body dynamic model is used to evaluate the vibration effect to the seated subjects.
Structural and Kinematic Aspects of a New Ankle Rehabilitation Device
Authors: Racu Cazacu Cristina Magda , Doroftei Ioan
Published: October 2014

This paper discusses structural and kinematic aspects of a novel ankle rehabilitation device. This device will facilitate the ankle recovery, providing two types of motions: pitch and roll. The platform is design to be light weight, easy to realize and low cost (comparing to actual devices on the market). The difficulty of the exercises can be gradually increased until we reach full ankle recovery.
Stresses and Displacements for Virtual Models of Healthy and Osteoarthritic Knee Joint
Authors: Tarniţă Daniela , Catana Marius , Tarnita Dan
Published: October 2014

This paper presents advanced modeling and simulation methods, using the latest generation of CAD-CAE applications. For the geometric modeling of human knee joint embedded applications as DesignModeler, SpaceClaim under Ansys Workbench software package were used. The objective of this study is to present our contributions on the modeling, simulations and finite element analysis of the healthy and osteoarthritic human knee joint in order to quantify and investigate its biomechanical behavior. The main objective of this article is to present a complex three-dimensional model of the healthy knee joint and of the osteoarthritic joint which shows a 15otilt in varus, the joint being affected by osteoarthritis in both compartments, in order to predict stresses and displacements in their individual components. The applied forces were equal with 800 N and 1500 N. Finally the results obtained for normal knee and for OA knee joint are compared.
3D CAD, CAM and Rapid Prototyping Applied for Cam Fabrication
Authors: Besnea Daniel , Ionascu Georgeta , Avram Mihai , Bogatu Lucian , Spanu Alina
Published: October 2014

In this paper, a comparison between CNC manufacturing and Rapid Prototyping technology (FDM – Fused Deposition Modeling process), applied for a cam fabrication, is presented. In the products development area, a substantial support is offered by models, as intermediate between product configuration and technology design. The CAD/CAM/CNC technology is a widely used technique for creating prototypes, as well as production parts, using a subtractive type material-removal procedure from a semi-manufactured article. The rapid prototyping (RP) technologies are additive processes, where the part is built up layer by layer until done, directly from the 3D CAD model, within the precision limits of the chosen process. Similarities and differences between these two coexisting computer driven prototyping processes, the subtractive CNC 3 – axes milled part production and the additive RP/ FDM technique, are pointed out for a disk cam manufacturing as sample part.
New Solution for Telescopic Robotic Arm
Authors: Bogdan Laurean , Toma Emanoil
Published: October 2014

This paper deals with a Robotic arm actuated by a monomobil telescopic planetary gear and servo DC motor. Experimental model of robot was designed and manufactured at the Faculty of Engineering from Sibiu, (Patent no. 112418 CI6.B25J 18/02). The Servo DC as actuator drives a reel. Wires on the reel will produce displacement of telescopic modules from robotic arm structure. The reference as a voltage for future arm displacement is provided by a PWM generator. The rotation of the reel in one way or another has the effect of lengthening or shortening robotic arm. Robotic arm length is directly related to the PWM signal. Control of robotic arm positioning is done with a linear transducer.
Teodor: A Semi-Autonomous Search and Rescue and Demining Robot
Authors: de Cubber Geert , Balta Haris , Lietart Claude
Published: October 2014

In this paper, we present a ground robotic system which is developed to deal with rough outdoor conditions. The platform is to be used as an environmental monitoring robot for 2 main application areas: - Humanitarian demining: The vehicle is equipped with a specialized multi-channel metal detector array. An unmanned aerial system supports it for locating suspected locations of mines, which can then be confirmed by the ground vehicle. - Search and rescue: The vehicle is equipped with human victim detection sensors and a 3D camera enabling it to assess the traversability of the terrain in front of the robot in order to be able to navigate autonomously. The paper discusses both the mechanical design of these platforms as the autonomous perception capabilities on board of these vehicles.
Optimal Design of the Control System for an Industrial Robot Using DOE Technique and Regression Model
Authors: Enescu Monica , Alexandru Cătălin
Published: October 2014

This paper approaches the optimization of the control system for an industrial robot with 6 axes (degrees of freedom), using design of experiments (DOE) and multiple linear regression models. The design objective refers to the desired trajectory of the end-effector, the aim being to minimize the difference between the desired (imposed) and current (measured) angles in the revolute joints of the robot. The correlation between the imposed trajectory of the end-effector and the corresponding angular motions in the six revolute joints is obtained through the inverse kinematic analysis. The characteristic parameters of the controllers are used as design variables in the optimization. The optimal design is based on the DOE Screening investigation strategy with the Full Factorial design type. This design was chosen in order to evaluate the effect of the factors and of their interaction on trajectory, and the levels of these factors needed to produce an optimal trajectory. By comparing actual data with data after optimization, it shows that the regression function is correct (in terms of goodness of fit). The dynamic model of the robotic system was developed in mechatronic concept, by integrating the mechanical device (designed in ADAMS/View) and the control system (MATLAB/Simulink) at the virtual prototype level. The optimization study is performed by using ADAMS/Insight.
Development of a Quality Indicator System for Haptic Exoskeleton Modules
Authors: Lovasz Erwin Christian , Mateas Marius , Gruescu Corina Mihaela , Mărgineanu Eugenia Zena , Carabas Iosif , Stan Sergiu Dan
Published: October 2014

The accuracy of outer space robotic applications using haptic devices requires high performance of the haptic device connected with the remote robot. The paper introduces and develops a quality indicator system, able to give overall information on the performances of the haptic device. The authors define several categories of indicators, such as the geometric, kinematic and dynamic. The geometric category comprises the position and orientation accuracy, the repeatability, the trajectory fluctuation, the resolution, the working space and the static relaxation. The kinematic indicators category comprises the speed fluctuation, the maximal acceleration and time accuracy. The dynamic indicators category comprises the force and torque fluctuation, the vibration amplitude and acceleration. All above-mentioned simple indicators open the path to complex indicators such as the pose accuracy in relation with the working space or the maximum force/torque in respect with the total weight. By introducing moderated indicators, the authors consider the specificity of each group of tasks or applications and in the end, they introduce a global moderated indicator in order to quantify rapidly the general performance level of a certain haptic device.
Control Characteristics of Haptic Exoskeleton Elbow Module Used in Space Robotised Applications
Authors: Mateas Marius , Lovasz Erwin Christian , Mărgineanu Dan , Ciupe Valentin , Zabava Eugen Sever , Maniu Inocentiu , Diaconu Aurel
Published: October 2014

In this paper the authors present some considerations regarding the necessity and the methods to calibrate an exoskeleton elbow module. Prior researches and studies are indicating that there is a difference between the haptic device force reaction and situation (position and orientation) and similar parameters at the level of the guided or slave robot. The authors are investigating the causes of the pose accuracy and force errors knowing the fact that for some space operations the fidelity of the teleoperation the geometric, kinematic and dynamic parameters are of great importance. The authors propose the measurement of the position accuracy, position repeatability, static relaxation under load, speed and acceleration, force and torque measurement in order to obtain a real correlation between the haptic device and the space robot parameters. Also the authors are considering the investigation of the unwanted vibration and the effect on the teleoperation parameters. Considering the importance of calibration for the improvement of the general accuracy of teleoperation the authors are taking into account the development of several performance indicators as a consequence of the conclusions emerged from the calibration methods study above mentioned. Also they consider very important that the calibration methods must be specific for each application category and therefore moderated performance indicators are envisaged.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.
Augmented Reality Used for Robot Remote Control in Educational Laboratories
Authors: Pasc Ildiko , Csokmai Lehel , Popentiu-Vladicescu Florin , Tarca Radu
Published: October 2014

One of the main aspects of teaching in engineering education, including robotics engineering, is to experiment. Due to the complexity of the equipment involved, robotics research is expensive, thus limiting the access of researchers/students to perform activities of this kind. One possibility to access these devices is to share them with other universities and research centers from different locations in the world. The research team was focused on building a telerobotic educational lab operated via the web so that interested Internet users should be able – using augmented reality – to manipulate and share with other users the robot control. In this paper the specificity of the robot’s environment is the existence of a grid, drawn on the telerobotic working space.
Simulation of the Tooth Helix Angle Influence on the Vibration of a Single Stage Helical Gearbox
Authors: Korka Zoltan Iosif , Cojocaru Vasile , Miclosina Calin Octavian
Published: October 2014

The current trend in the construction of gearboxes, regarding the speed increase, favors the increase of the dynamic loads which are accompanying the operation of these kinds of machines. The phenomena of dynamic contact like frictions, collisions and shocks which are taking place in cinematic couples, engines and mechanisms during their movement, are generating vibrations in a wide range of frequencies. Vibrations produced by gearboxes became characteristically indicators for assessing their quality. Therefore, the decrease of vibrations produced in the gear transmissions became lately a priority, being one of the combat methods in the fight against environmental pollution.
Low Speed Linear Actuator for Accurate Orientation of Concentrated Solar Convertors
Authors: Neagoe Mircea , Saulescu Radu , Munteanu Olimpiu , Burduhos Bogdan
Published: October 2014

The accurate orientation of concentrated solar converters (e.g. solar parabolic dish, concentrated photovoltaic) requires small stepwise angular displacements at short intervals of time aiming to track accurately the sun. These tracking systems are usually operated, especially the elevation movement, by low speed linear actuators (LSLA) with special configuration. The main drawbacks of the known LSLA solutions refers to the high constructive complexity of the intermediate gear reducer and its relative low efficiency due to the high value of the kinematic ratio, required to harmonize high speed motors and low speed outputs. The paper presents a geometrical synthesis algorithm and kinematic simulations of a new LSLA variant, proposed by the authors, consisting of a classical electrical motor (AC or DC), a linkage reducer transmitting intermittently the motion to a final irreversible screw-nut transmission through backstopping clutches. Compared to the known solutions, the proposed actuator has the advantage of decreasing the structural, constructive and technological complexity of the intermediate gear reducer (between the motor and the irreversible screw-nut transmission) by replacing it with a linkage type speed reducer and backstopping clutches, achieving a fixed or adjustable high kinematic ratio.
Hybrid Particle/Fiber Polymer Based Composites Analysis Based on DMA Data vs. Material Property Predictions
Authors: Motoc Luca Dana
Published: October 2014

The paper aims a comparison with respect to the dynamic mechanical properties of few hybrid polymer based composite architectures based on experimental data against micro-mechanical models based numerical predictions. The hybrid polymer based composites considered were particle-fiber combinations reinforced within an unsaturated polyester resin to provide different architectures. Variations in storage modulus (E’), loss modulus (E’’) and damping factor (tan δ) with temperature increase and different particle volume fraction were investigated. Data comparison reveals the herein composite architectures’ performances over the benchmark and enables further insight into the material development and characterization issues.
Surface Generation by Material Removal in Manufacturing Processes from Machine Building
Authors: Slătineanu Laurenţiu , Coteaţă Margareta , Besliu Irina , Dodun Oana , Radovanović Miroslav
Published: October 2014

The examination of the main machining methods applied in manufacturing processes from machine building and based on material removal from workpiece highlights essentially the existence of distinct processes able to generate material. An analysis of certain machining methods able to develop processes of material removal from workpieces was initiated by taking into consideration the principle machining schema and the capacity of generating machined surfaces. One concluded that within distinct machining processes, various phenomena are applied in order to obtain material removal from workpiece.
Constitutive Parameters of Mechanical Behaviour Law for Poly (Ether-Ether-Ketone) Based Composites with Carbon Nanotubes and Carbon Fibres
Authors: Trufasu Dan Catalin , Besnea Aida Maria , Andrei Gabriel , Bastiurea Marian , Cotet Adrian
Published: October 2014

Phenomenological constitutive equations are applied successfully to predict stress-strain relationship for semi-crystalline polymers at high strain rates encountered in mechanical tests. The parameters of mechanical behaviour law for polymer composites with nanoscopic additives and carbon fibres can be identified by applying a known law over a lot of data obtained from compressive tests. The objective of this study is to investigate the applicability of the model G'Sell - Jonas in the case of poly (ether-ether-ketone) composites with carbon nanotubes and carbon fibres.
Aspects of Modeling and Optimizing Air Circulation Currents in a Car Cabin
Authors: Caunii Vasile , Sachelarie Adrian
Published: October 2014

Air conditioning system is one of the main components of modern cars, which defines the level of comfort, its performances directly affecting the car performances. In order to have a car with high level of thermal comfort, the air-conditioning system must be efficient in terms of energy, it has to perform many functions regarding the microclimate control (control of temperature, humidity, filtration), and in addition must fulfill safety and security functions in circulation (demisting and defrosting). Also vehicle air-conditioning system can significantly influence fuel economy and tailpipe emissions of conventional and hybrid electric vehicles (HEV) and reduce electric vehicle (EV) range.
Effects of Temperature Distribution on Operational Parameters of a Spark Ignition Engine
Authors: Girbaci Mihai Alin , Agape Iulian , Gaiginschi Lidia
Published: October 2014

In recent years, automobile manufactures have been required to meet stringent fuel consumption specification. An important factor with regard to this problem is the operating temperature and its effect on functional parameters. In this paper, the effect of heat transfer on the various parameters such as inlet mixture temperature, compression ratio, exhaust gas, fuel consumption, lubrication oil of a spark ignition engine is studied. A number of studies have been reported which dealt with the thermal analysis of the structure of internal combustion engine. Because of the complexity of the problem, these analyses are approximate. Thus, to improve the accuracy of the results of the thermal analysis, we must work with experimental results prelevated from a 24 valve – 6 cylinder spark ignition engine. Included are comparisons between cooling characteristics of the water solutions with those of 100% ethylene glycol coolant.
Qualitative Estimation Criterion of Direct Injection Diesel Engines Performance Prediction for Stationary and Industrial Applications
Authors: Mărdărescu Vladimir , Ispas Nicolae , Nastasoiu Mircea
Published: October 2014

Our approach is to define as accurately as possible, the opportunities of forecasting the environmental and energetically qualities of direct injection Diesel engines for stationary and industrial applications. This research requires the validation of new energy solutions or injection process. Knowing that test bench research of internal combustion engines is a task that requires highly qualified personnel and very expensive equipment for investigate the combustion process, a research program to define the best technical solution involves significant costs. The energetically solution of an internal combustion engine, similar to those examined in this paper, is defined by the following guidelines and parameters: - Control of mixture formation; - Compression ratio; - Average swirl intake number channel; - Geometry of the intake and exhaust cams; - Diagram of distribution; - Drive cam type injection pump; - Geometry of the combustion chamber; - Type and nozzle geometry (sack configuration and l / d ratio ); - Needle stroke; - The diameter and length of the injection pipe; - Amount of injector opening pressure (for hydraulic injectors); - Type of delivery valve; - Time of injection. Based on experience gained during the test at the test bed, we proposed a criterion for assessing qualitative performance of Diesel class discussed above. This criterion refers to environmental and energetically performance, as a prediction of performance at nominal regime, after shorten tests with cold engine.
Safety against Derailment for Railway Vehicles
Authors: Popa Gabriel , Sebesan Ioan , Spiroiu Marius Adrian , Badea Claudiu Nicolae
Published: October 2014

The shock attack occurs at a railway vehicle circulation in a curve in which a discontinuous bend appears, mathematically represented by an angular point. In this point, shock angle produces an abrupt change of direction of the vehicle, respectively a dynamic shock force.The paper presents a mathematical model used to determine the dynamic force shock and its influence on vehicle guiding safety. The study was applied to the tank wagon on bogies for transportation of petroleum products, because such vehicles generally have derailed at circulation in curves in which have occurred accidentally discontinuous bends.It shows that the dynamic force may lead to an unacceptable increase of guiding force Y at leading axle of the vehicle, and therefore to overcome the (Y/Q)lim, which defines the limit of derailment, Q being the load on the attacking wheel.The conclusions indicate constructive measures to be taken to ensure the safety of the vehicle guiding at circulation in curves.
Thermo-Chemical Recuperation as an Efficient Way of Engine's Waste Heat Recovery
Authors: Tartakovsky Leonid , Baibikov Vladimir , Gutman Marcel , Poran Arnon , Veinblat Mark
Published: October 2014

It is known that about 30% of fuel energy introduced to an internal combustion engine (ICE) is wasted with engine exhaust gases. One of the promising ways of waste heat recovery is thermo-chemical recuperation (TCR). For the purpose of TCR realization, in principle any fuel may be used. However, utilization of renewable bio-alcohols, especially ethanol or methanol is the most favorable. The advantages of TCR over turbocharging are in the fact that its energy transfer is not limited by isentropic expansion and that the reforming process improves the fuel properties. A comprehensive theoretical analysis of the ICE with TCR was carried out using the developed model for simulation of the joint operation of ICE with alcohol reformer, when the ICE is fed by the alcohol reforming products and the energy of the exhaust gases is utilized to sustain endothermic reforming reactions. Simulation results show that it is possible to sustain endothermic reforming reactions with a reasonable reactor size. Modeling results point out a possibility of engine's efficiency improvement by up to 13% in comparison with ICE feeding by gasoline together with achievement of zero-impact pollutant emissions.
Combined Cycle Units for Terrestrial Propulsion - Dimensional Approach
Authors: Balanescu Dan Teodor , Homutescu Vlad Mario , Hritcu Constantin Eusebiu , Talif Sorinel Gicu
Published: October 2014

High performances and operation with low water consumption are mandatory but not sufficient conditions for the Combined Cycles Units implementation in the terrestrial propulsion systems field. There is another restrictive condition, which refers on the admitted size. That is why a dimensional analysis of the Combined Cycles Units is mandatory. In this view, paper presents the results of the dimensional analysis of a small scale Combined Cycles Unit for terrestrial propulsion, based on a two-pressure-levels Steam Cycle and operating with liquid fuel.
Micro-Alloying Influence on Hot Work Tool Steel Properties
Authors: Adoroaei Cristian George , Axinte Mihai , Chicet Daniela Lucia , Stanciu Sergiu
Published: October 2014

The paper is a practical study, in which the authors have proposed to improve the reliability in operation of hot work tool steels, used for the manufacturing of seamless steel tubes.There were developed samples of hot work tool steel with different chemical compositions by micro-alloying with Mo. The samples were studied in order to investigate their structure and the relations between the microstructure and in-situ behavior.
Research on the Processes of Gas-Air Mixtures Formation
Authors: Bica Marin , Sofronie Marius Sorin , Cernaianu Corina Dana
Published: October 2014

The mixtures formation process based only on molecular diffusion proved to be the slowest. The mixing speed is reduced due to the collision of molecules of two or more gases which are subjected to the mixing process. The gases concentrations have an important role in mixture formation. Air is one of the combustion gases in the case of mixing in order to achieve the burning process.
Study Regarding the Wind Action on the Functioning of Chimneys
Authors: Ciocan Vasilică , Verdeș Marina , Popovici George Catalin , Balan Marius Costel , Burlacu Andrei , Verdes Alexandru
Published: October 2014

Thermal power capacities, operating with different fuels, located near localities, generate significant amounts of flue gases. Gases contain various components which have standardized reasonable limits on concentration in the soil and in the buildings vicinity. The chimney must be designed and sized to achieve dispersion of gases and ensure concentrations below acceptable limits. This paper proposes a study on flue gas dispersion for different wind speeds and different chimney heights.
Considerations about the Role and Efficiency of the Transceiver's Heat Sink during Critical Situations
Authors: Davidescu Arjana , Savii George G. , Mateas Marius , Sticlaru Carmen
Published: October 2014

Thermal analysis of electronic equipment is becoming one of the primary aspects of many researches considering the trend line of reducing the size and increasing the speed. As the power of these systems increases and the space allotted to them decreases, heat flux or density becomes a critical factor in designing electronic equipment. The paper deals with thermal behavior of a particular heat sink designed for a VHF-UHF dual-band transceiver with a maximal power of 50 W. In this case, the electrical part generating this amount of power, is a MOSFET having a junction maximal temperature of 150 °C. A 3D CAD model was developed in proEngineer and finite element analyses were run in ANSYS in order to establish the best functioning conditions of the transceiver.
Gamma-Type Stirling Motor-Driven Compressor
Authors: Homutescu Vlad Mario , Balanescu Dan Teodor
Published: October 2014

Paper is analyzing an engine-driven gamma-type Stirling compressor by means of an isothermal physico-mathematical model. The maximum performances of an engine-driven gamma-type Stirling compressor (working after a quasi-Stirling thermodynamic cycle) are obtained. By using these maximum performances as reference, a comparison between different physical embodiments of engine-driven gamma-type Stirling compressors can be achieved.
Physico-Mathematical Model of the Theoretical Gamma-Type Stirling Motor-Driven Compressor
Authors: Homutescu Vlad Mario , Balanescu Dan Teodor
Published: October 2014

Paper is analyzing a physico-mathematical isothermal model of the theoretical engine-driven gamma-type Stirling compressor. The absolute maximum performances of an theoretical engine-driven gamma-type Stirling compressor (that function after a thermodynamic cycle comprising two isochoric processes of heating and cooling the agent, one isothermal compression and one partially-cooled expansion process) are obtained. Using these absolute maximum performances as reference, it is possible to assess the degree in which several real physical constructions of this machine can approach to the ideal functioning.
Experimental Determination of the Yield Stress for Copper, Cu_99.75
Authors: Cazac Alin , Gheorghiu Diana Antonia , Baciu Constantin , Toma Stefan Lucian , Bujoreanu Carmen , Bejinariu Costică
Published: October 2014

The paper presents the determination of the yield stress for copper, Cu_99.75, at standard ambient temperature, by means of upsetting of cilyndrical specimens, taking account the allowable degree of deformation of this material. The outcomes achieved can be used both plastic deformation processes and volumic deformation simulation of copper Cu_99.75.
Pressure Injection Influence on the Combustion Process
Authors: Sabau Adrian
Published: October 2014

Computational simulation for the combustion process in a DI diesel engine was performed through a code made by the author [1]. Two conditions of different injection pressure were examined in the simulation. The injection pressures are 150 MPa and 500 MPa. The combustion phenomenon was modeled as a combined process of formation of a combustible mixture and a chemical reaction. The rate of mixture formation was assumed to be dependent on the turbulence characteristics and the concentration of species in each computational cell. The rate of chemical reaction is described as an Arrhenius equation. The result agrees with the experimental result qualitatively, and the effect of injection pressure on the combustion process is well predicted.
Silicon Influence on the Cast Iron Structure
Authors: Chicet Daniela Lucia , Cojocaru-Filipiuc Vasile
Published: October 2014

Chemical element silicon, placed in liquid iron behaves differently, through the influence they exert on the metallographic structure. The factors that define their influence are the melt temperature, melting bath temperature variation dynamics, the amount that is inserted into melting bath, chemical shape etc.Refining of metallographic structure was found when FeSi was used with 35% si 73% Si.
Results of the Numerical Simulation of the Entropy Flow Generated at the Fluid Flow with Friction and Heat Exchange
Authors: Vartolomei Haralambie Mihail
Published: October 2014

The minimization of the entropy generation is fundamental for the thermodynamic design. Based on theoretical relations contained in the references [1,2,3,4], a numerical simulation program of the entropy flow generated at the flow with friction and heat exchange was developed, whose results are included herein. From their analysis it is clear that between irreversibility and design parameters there isn’t a monotonous dependence, and that, by the mere intuition, without a directed concern, we cannot predict the effect of a design change on the global configuration of irreversibility.
Experimental Determination of the Heat Recovery Boiler Effectiveness of a Gas Turbine Plant
Authors: Vernica Sorin Gabriel , Hazi Aneta , Hazi Gheorghe
Published: October 2014

Increasing the energy efficiency of a gas turbine plant can be achieved by exhaust gas heat recovery in a recovery boiler. Establishing some correlations between the parameters of the boiler and of the turbine is done usually based on mathematical models. In this paper it is determined from experimental point of view, the effectiveness of a heat recovery boiler, which operates together with a gas turbine power plant. Starting from the scheme for framing the measurement devices, we have developed a measurement procedure of the experimental data. For experimental data processing is applied the effectiveness - number of transfer unit method. Based on these experimental data we establish correlations between the recovery boiler effectiveness and the gas turbine plant characteristics. The method can be adapted depending on the type of flow in the recovery boiler.