bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of Products from Hydrothermal Carbonization of Bamboo
Authors: Wu Xue Hua , Luo Jia , Wang Hua , Fang Zhen
Published: October 2014

Hydrothermal carbonization of bamboo was conducted at 300-370 °C for 1 h. Products in solid, oil, aqueous and gaseous phases were collected and studied. More than 20% carbon was water-soluble. Oil phase was mainly hydroxylated derivatives of benzene. Hydrochars were composed of many microspheres in morphology, with carbon content of 72.1-81.0%. Around 50-60% of carbon in bamboo remained in hydrochars. High heating value of hydrochars was 1.3-1.6 folds of original bamboo. The hydrochars had higher antioxidative stability than pyrolysis biochar.
Contribution on the Optimization of the Spur Gears Design Process Using Software Application
Authors: Plesu Gheorghe , Cazan Stelian
Published: October 2014

This paper illustrates a method, in conformity with Standards [10 - 14], regarding gear design. The optimization process using this method consists in reducing the number of design steps and also in its accuracy. This method takes into consideration the functionality of gears. This method, called also the operational method [1], involves 10 kinematic and dynamic restrictions, that provide a direct calculus of gears, without any iterations. The standard methods require successive iterations, until the appropriate result is obtained. The comparison between these methods is presented below. The kinematic and dynamic restrictions, being defined as mathematical functions, could easily be implemented in a programming language.
Dynamic Optimization of a Single-Seater Car Suspension System
Authors: Totu Vlad , Alexandru Cătălin
Published: October 2014

This work deals with the multi-objective dynamic optimization of the suspension system used for the front wheels of a single-seater vehicle. A half-car model is developed, considering the front suspension system mounted, while the rear suspension is replaced with a fictive spherical joint that is placed at the rear axle level. The purpose of the dynamic optimization is to minimize the chassis oscillations (yaw, pitch and roll), the monitored value for each design objective being the root mean square (RMS) during the dynamic simulation. The locations of some important attachments from the suspension system are used as design variables for the dynamic optimization. The dynamic model is analyzed in the passing over bumps regime, the wheels being anchored on driving actuators, whose motion simulate the road profile. Specific modules of the MBS (Multi-Body Systems) software environment MSC.ADAMS are used in this study.
Some Consideration Regarding the Models for Collisions with Plastic Indentation
Authors: Alaci Stelian , Ciornei Florina Carmen , Filote Constantin
Published: October 2014

The paper presents a comparative study between experimental results for a collision with plastic deformations and a theoretical model from literature. A review of collision models is briefly made and a theoretical model is selected after an analysis between theoretical results and data from experimental researches. The theoretical results are evaluated versus experimental data from laser scanned post collision indentations, for the ball-plane impact. The theoretical model requires improvements by considering additional impact parameters.
Optimizing the Shape and Size of Cruciform Specimens Used for Biaxial Tensile Test
Authors: Andrusca Liviu , Goanta Viorel , Barsanescu Paul Doru
Published: October 2014

Testing cruciform specimens subjected to biaxial tension is one of the most widely used experimental techniques and more accurate at this time to determine the mechanical properties of materials and to verify the failure theories. This type of experiment allows the continuous monitoring of behavior of materials from the beginning of deformation until fracture under different ratios of forces and directions of the deformation, which transforms it into a very versatile testing method. We have varied the number of parameters and their values in order to achieve a uniform distribution of biaxial state of stresses and strains in the area tested. In theory, any material can be tested by stretching a biaxial cruciform specimen, but must be investigated in what way the shape of the specimen influence the data obtained. In this paper are presented the requirements that must be fulfilled by the samples used for tensile / compression biaxial tests and the design of cruciform specimens through FEA that meet these demands.
Optimization Design for Car Suspension Elastic Elements
Authors: Bujoreanu Carmen , Stirbu Cristel
Published: October 2014

To realize an efficient car suspension control (for instance in technical inspection) it is important to use easy measurable variables. This is the reason for developing optimization techniques in order to simplify and improve the engineering design process. The paper presents an optimization process of a torsion bar spring included in the car suspension involving the following steps: modeling and analyzing the torsion bar spring behaviour, definition of the optimization objective and the specifications for the proposed solution choosing an appropriate methodology to satisfy the design objectives. It has been used a Min-Max optimization method to highlight the vibration response (in terms of RMS) of the system. CAD analysis and MatLAB optimization are performed on the car suspension elastic element and the obtained results provide an optimum vibrational response and constructive design. This combination of these analyses can be considered an efficient tool in order to ensure the driver and passengers comfort according to the standards.
Vibration-Based Crack Detection in L-Frames
Authors: Ntakpe Jean Louis , Gillich Gilbert Rainer , Muntean Florian , Praisach Zeno Iosif , Lorenz Peter
Published: October 2014

This paper presents a novel non-destructive method to locate and size damages in frame structures, performed by examining and interpreting changes in measured vibration response. The method bases on a relation, prior contrived by the authors, between the strain energy distribution in the structure for the transversal vibration modes and the modal changes (in terms of natural frequencies) due to damage. Using this relation a damage location indicator DLI was derived, which permits to locate cracks in spatial structures. In this paper an L-frame is considered for proving the applicability of this method. First the mathematical expressions for the modes shapes and their derivatives were determined and simulation result compared with that obtained by finite element analysis. Afterwards patterns characterizing damage locations were derived and compared with measurement results on the real structure; the DLI permitted accurate localization of any crack placed in the two structural elements.
Misalignment Effects in Cylindrical Roller Bearings
Authors: Benchea Marcelin , Iovan Dragomir Alina , Cretu Spiridon
Published: October 2014

All cylindrical-rollers profiles exhibit severe discontinuities in the end chamfer zones; the ZB profile includes two more at the common points of the crowned radius and straight line, Fig. 1.
Consideration Regarding the Inverse Kinematics of a Rowing Skiff under the Action of the Oars Movement
Authors: Chirazi Marin , Budescu Emil , Merticaru Eugen
Published: October 2014

The paper deals with the kinematical approach of the trajectory of movement of an academic rowing skiff with a view to determine a given racing speed of the boat. It uses inverse kinematics since this method allows obtaining analytical calculus formulas for the movement of paddles in their two moments of motion: active and passive strokes. Movement of the paddles while following an arc-shaped trajectory outlining a sphere-like quadrilateral requires different values of amplitude of angular displacement of the paddles according both to anthropometrical values of the athlete and to his physical and technical training. The numerical application is made for several values of these angles which define the arcs of the circle for active and passive curves and for the moments between the two strokes (angle of the paddle while slicing in and out the water). These amplitudes of angular displacement are being considered, from the point of view of the horizontal component, equal to the speed of the skiff while imposing the linear speed of the paddle, and they would help determining movement frequencies of the paddle while following the sphere-like quadrilateral trajectory.
The Influence of the Misalignment on Load Distribution in Angular Contact Ball Bearings
Authors: Damian Ioan , Paleu Viorel , Cretu Spiridon
Published: October 2014

The paper presents a model for quasi-static analysis of angular contact ball bearings. This model allows the computation of the load distribution on ball and races contacts as a function of radial and axial inner ring displacements, including the effect of the misalignment between the inner and outer rings. The results show the influence of the misalignment on ball and races load distribution.
Tribological Study of Ecological Lubricants Containing Titanium Dioxide Nanoparticles
Authors: Ilie Filip , Covaliu Cristina , Chisiu Georgiana
Published: October 2014

Titanium dioxide (TiO2), belonging to the family of transition metal dichalcogenides (together with molybdenum disulfide (MoS2) and tungsten disulphide (WS2)), is well known for its solid lubricating behaviour. Thin films of TiO2 exhibit extremely low coefficient of friction in dry environments, and are typically applied by mixed in oil, grease or impregnated into porous matrix of powdered materials. Current researches in many areas imply the using of different types of nanoparticles in the composition of oily lubricants. Results of these researches upon the friction couples show that nanoparticles contained by lubricant can improve the tribological properties, the friction-wear reduction and the lubrication effect. When nanomaterials are used to improve lubrication effect, the selection of metal is very important. In this paper, the authors chose for investigating the tribological properties of two samples of TiO2 with the mean diameter of 15 nm (n-TiO2) and 250 nm (m-TiO2), under different friction conditions. The tribological properties of TiO2 nanoparticles mixed in the ecological lubricant oil were investigated using a four-ball tribometer and a block-on-ring tribometer and show the lowering of the friction coefficient in comparison to the lubricant base oil. The finally obtained lubricant is not considered toxic for the environment. The analyses of surface film composition, characterized with the help of X-ray photoelectron spectroscope (XPS) and scanning electron microscopy (SEM) images showed that the deposed nanoparticles form a protective film (TiO3) allowing for an increase in the load capacity of friction couple. XPS and SEM were used to examine the morphology of the wear track, after the four-ball experiment. The main advantage of the nanoparticles is ascribed to the release and furnishing of the nanoparticles from the valley onto the friction metal surface and their confinement at the interface. The TiO2 nanoparticles showed lower frictions coefficient and higher wear resistance as compared to the common TiO2 particles (about 1.5 μm in diameter(c- TiO2)) on a four-ball machine, which were caused by the microstructure of the protective film and serve as perfect intermediate lubricants between the contact surfaces.
About the Friction of the Wiper Windscreen Contact
Authors: Musca Ilie , Musca Gavril , Vultur Dumitru Cristian , Ungurean Bogdan Vasile
Published: October 2014

In order to study the influence parameters for the wiper-windscreen friction, a test system was built, using an assembly of a car plane auto rear window glass, with the electrical motor, the wiper mechanism and also a wiper with a modified arm (by inserting a transducer to measure the friction force, based on tensometric strain gauges). Also on the wiper arm, on the opposite side of the arm/blade connection (located approximatelly at the middle of the blade length) a loading system was mounted. Different loading forces can be applied to the blade contact by gravity by simple changing the mass placed on this system. A large number of experiments were performed for different combinations of the values for the blade oscillating period and for the normal force in dry and wetted conditions for the blade-windscreen contact. The obtained results, reveal a direct correlation of the friction force with the load mass and with the relative speed in the contact (blade moving period). A higher friction occurs for the dry contact. This force has a higher increasing tendency for this contact than for the wetted contact when a stabilisation tendency of the friction force occurs.
Friction Torque Measurement in Partial Hybrid S-C Angular Contact Ball Bearings
Authors: Paleu Viorel , Damian Ioan , Stirbu Cristel
Published: October 2014

To monitor the friction torque evolution in tandems of angular contact ball bearings, a new testing device is developed. New partial hybrid bearings from 7206C series are obtained by combining 8 steel balls with 4 silicon nitride balls of the same diameter equally spaced in the cage, these bearings being denoted hereafter as 8S-4C type. For comparison, tests are carried-out also on conventional all-steel bearings and hybrid bearings with all the steel balls replaced by silicon nitride balls. The equilibrium temperature of the all-steel, hybrid and 8S-4C ball bearings is determined by tests. At high speed and light axial load, the 8S-4C ball bearings withstand to an oil shut-off test of one minute, while the similar all-steel bearings seized. The 8S-4C partial hybrid ball bearings can be an advantageous solution comparative to more expensive all hybrid bearings, avoiding the scuffing due to the self-healing effect induced by the higher hardness of the silicon nitride balls.
Chain Tracking System for Solar Thermal Collector
Authors: Ciobanu Daniela , Jaliu Codruta , Saulescu Radu
Published: October 2014

The use of renewable energy sources represents a continuous concern for the researchers around the world. The main source of renewable energy, the sun can be used for producing hot water / heating or electric energy, by means of solar collectors. The concentrating solar collectors contain tracking systems for orientation on one or two axes. The tracking system for the elevation motion has to ensure a reduced angular stroke. The mechanism that is usually included in the system structure is of linkage type, being driven by a linear actuator. The mechanism has the advantages of low complexity and reduced cost. In the case of diurnal motion, the angular stroke is larger, being usually obtained with gears or chain drives. The actuation is achieved by motor-reducers with high transmission ratios and costs. In order to reduce the costs, mechanisms containing linkages driven by linear actuators are proposed in literature. These tracking systems have the disadvantage of large overall dimensions. To reduce this disadvantage, the paper proposes a new variant of chain tracking system driven by a linear actuator. Then the proposed tracking system is structurally optimized, process that generates 6 new variants of mechanisms. These solutions eliminate the problems created by the hyperstatical constraints and avoid blocking in case of assembling errors.
Dependence between the Favourable Initial (Residual) Stresses and Durability of the Ball Screws
Authors: Puiu Vasile
Published: October 2014

This work is based on theoretical and experimental researches on increasing the carrying capacity and durability of the ball screws used on machine tools by creating favourable initial compression stresses (non-conventional treatment) in the surface layer of the elements into contact, so that these stresses keep their effectiveness during usage.
Friction in Bearings of Parallel Axes Transmissions
Authors: Todi-Eftimie Alina , Velicu Radu , Brands Christoph , Schlerege Frank , Lates Mihai Tiberiu
Published: October 2014

The paper presents a theoretical approach and experimental analysis of bearings friction from a parallel axes transmission. The bearings are components of a testing rig for determining friction losses in chain drives, depending on the tensioning force, speed, temperature and quality of lubrication. Friction in chain is calculated by subtracting the bearing friction from the global (chain and bearings) friction. It is of maximal importance in the correct evaluation of experimental measurements on the rig, to have accurate data on the friction on bearings.
Jacq Effect Influence on Thermomechanical Contact Fatigue
Authors: Sandu-Ville Florin Tudose
Published: October 2014

The paper take into account the thermo – mechanical contact fatigue as an important component of global thermo – mechanical contact wear. This phenomenon is very important for contacts localized in enclosure, working non – stop, with few possibilities of intervention. It is presented in a synthetical way the theories concerning the location of the decisive stresses for mechanical rolling contact fatigue in connection with the primary crack in deterioration . Also, are made some considerations about the thermal effect Jacq and the consequences for the temperature gradient in a metallic wall. Most of the technological processes are carried out with heat release. An illustrated example is the rolling mill process where the thermal tide is at a high level. The reability evaluation for rolling mill rollers it is in connection with the position of the primary crack under the contact surface. This position give the type of the decisive stress for destruction. The importance of the paper is the connection between the thermal effect Jacq and the thermomechanical contact fatigue. Also, the influence of the changing slope for the temperature gradient concerning the position of the primary crack under the contact surface in thermomechanical contact fatigue [1].
Some Aspects Concerning Modeling the Eye Plant without Ocular Deviations
Authors: Barbu Daniela Mariana
Published: October 2014

Oculomotor plant and saccade generator are the basics of the saccadic system. The purpose of this paper is mainly focused on mathematical models of horizontal eye movement system. In this respect, it is presented a model for the mechanics of horizontal eye movement. The oculomotor system is presented incorporates known physiological dynamics and musculotendon complex geometry. Developing muscle strength can be described by a two-component version of the model Hill and consists of a passive and active contractile component. The active component includes force-velocity and force-length characteristics of the muscle. Passive component accounts for elastic and viscous effects. Couple neuronal activation dynamics controls that is appropriate for judder from muscle mechanics.
Prehension of the Small Cylindrical Objects by the Human Fingers: Friction and Adherence Processes
Authors: Barnea Alexandru , Oprişan Cezar , Olaru Daniela
Published: October 2014

The authors experimentally investigated the friction and adherence between small cylindrical objects and human fingers. The experiments were realized for low normal loads between small cylinders and human fingers and low sliding speed. Were obtained variation of adherence and sliding forces as function of time during the reciprocating-sliding of the small cylindrical bodies on soft skin of the human finger. Were evidenced cyclically deformed and relaxed of the lateral skin as a result of reciprocating motion of the cylinders and were determined the corresponding forces. Also, was evidenced the “butterfly” configuration between the tangential force and lateral displacement.
Fracture Resistance of Prosthetic Restored Teeth with Fiberglass Posts versus Metallic Posts
Authors: Margarit Ruxandra , Sandu Marin , Tanasescu Alice , Oprea Raluca Manuela , Andrei Oana Cella
Published: October 2014

Because of the great amount of hard dental tissues loss, most of non-vital teeth must be prosthetically restored using a post. The anchorage of these posts is based on enlarging the root canal, so the question is what type of endodontic post is more appropriate to use in order to ensure a favorable prognosis of these teeth, avoiding as long as possible their extraction. Loss of teeth is affecting not only the oral cavity and the dento-maxillary system, but also the quality of life of the patients, with both psychological and general health consequences. Even treated, the edentulous state determines major changes in diet and can be a cause of gastrointestinal disorders. Thisin vitroexperiment tested the resistance to fracture of non vital teeth restored with different types of posts, in order to find out which type is best to use for their restoration. From the of this in vitro experiment it has been observed that in the case of teeth restored with metal posts, regardless of the diameter of the post, the failure of the sample was represented by root fracture. In the case of the teeth restored with fiberglass posts, the failure was caused by the fracture of the post or the fracture of the coronary part of the tooth.
3D Analysis for Identification of the Proper Type of Post to Restore the Endodontic Treated Teeth
Authors: Margarit Ruxandra , Sorohan Stefan , Tanasescu Alice , Dăguci Constantin , Andrei Oana Cella
Published: October 2014

Abstract. The problem of root fracture in case of prosthetically restored non-vital teeth is a common concern among clinicians. These fractures are caused by increasing the diameter of the root canal during the endodontic retreatment and occure on the dental arches in both the anterior and posterior area. Such treatment failures lead to extraction, therefore the physician’s goal is to limit as much as possible their occurrence. We used finite element analysis method to find out what type of corono-radicular restoration is more appropriate in order to avoid fractures. We selected two of the most commun posts used in our country: metallic NiCr casted RCR (corono-radicular reconstruction) and prefabricated fiberglass endodontic posts of various diameters and we analyzed the existing tensions in the dental structures that would predispose the root to fracture.
Modeling and Simulation of Physical Parameters of Human Respiratory System
Authors: Meireles Catarina , Machado José , Leão Celina P.
Published: October 2014

The respiratory system, due to its non-linear behaviour, is of difficult representation through fixed physical components and common control systems. Therefore, mathematical equations, that represents the respiratory cycle; mechanical components, giving dimension and movement to the simulator; and the electronic components, allowing data acquisition and system control are some factors that must be known and synchronized. The presented work describes the implementation of a mathematical model (in MatLab) that reproduces the non-linear behaviour of the respiratory system, allowing the characterization of different pathophysiological situations. In parallel a graphical interface was developed enabling the user track the change in air flow and volume handled during the respiratory cycle and build physiological profiles of different patients.
New Design Concept for Reducing Torque Wear on Implant
Authors: Mihai Simona , Filip Viviana
Published: October 2014

The hip (coxofemoral) joint is built so as to provide, at the same time, maximum stability and mobility, and is characterized by a very low wear rate and very low frictional forces thanks to the very good natural lubrication. In time, due to various reasons such as aging, joint illnesses, bone tumors, arthritis, injuries, coxofemoral joints may lose their self-lubrication ability, causing pains that make movement almost impossible. The therapeutic solution for coxofemoral joint illnesses is hip implant arthroplasty. Medical implants replacing the bone segments of coxofemoral joints are subjected to mechanical stress during walking and daily activities, which leads to wear in the long run. In the (most frequent) case of a bipolar hip implant, consisting of a femoral stem and femoral head, the area most affected by wear is the hip implant coupling, which represents the connection between the sphere-shaped proximal end of the femoral stem and the femoral head’s ball groove. Typically, the spherical proximal end of the femoral stem is made of metallic biomaterials (titanium and titanium alloys, cobalt-based alloys, stainless steels) or ceramic biomaterials (alumina, zirconia), while the femoral head’s ball groove is made of polymeric biomaterials (high-density polyethylene), metallic biomaterials or ceramic biomaterials. In the hip implant’s coupling there takes place a sliding friction whose coefficient depends on the nature of the touching surfaces (metal on metal, metal on polyethylene, ceramic on polyethylene, ceramic on ceramic). The wear that occurs in the coupling is due especially to the particles of material detached from the surfaces coming into contact. A worn coupling should be replaced by a revision surgery that the patient must go through, since loose particles generate severe joint inflammation. The objective of this paper is: -to point out the wear degree of the components forming the friction coupling of a hip implant, by presenting images, as seen on a video microscope, of two implants retrieved from patients after revision surgery -to present a new structural option for the construction of a hip implant coupling, by introducing two ball cages that replace the femoral head’s ball groove, which reduces the contact surface and replaces sliding friction with rolling friction (with a lower friction coefficient), thus diminishing the wear on the implant coupling.
Role of Surface Industrial Finishing Process of Joint Implant UHMWPE on their Tribological Behaviour
Authors: Popa Mihaela , Wang Na , Descartes Sylvie , Trunfio-Sfarghiu Ana Maria
Published: October 2014

Joint implants have as bearing couples metal on metal, ceramic on metal and metal on polyethylene. The most widely used bearing couple for artificial joint systems is the combination of a polyethylene (PE) acetabular liner and a cobalt–chromium (Co–Cr) alloy femoral head. Although highly used, it is known that wearing of the polyethylene part of total joint implants is the primary cause of premature failure of total joint replacements [1]. Polyethylene particles tend to migrate into the joint creating inflammation, ostelysis and, in the end the loss of the implant. Industrials use different method for the surface finishing process of the polyethylene part of joint implants that lead to different types of surface morphologies. In this study, using atomic force microscopy technique and tribological methods, we have investigated the influence of polyethylene surface morphology on mechanical properties, degradation and friction. Results have shown that polyethylene surfaces obtained by high speed turning machine lead to low friction coefficient and less degradation of the surface during friction test.
Singularities Classification for Structural Groups of Dyad Type
Authors: Duca Cezar , Buium Florentin
Published: October 2014

The paper deals with singularity problem of the closed-loop planar mechanisms. This problem is approached in addition with the force transmission quality in mechanism and mechanism self-locking. Another characteristic of this approach consist in the fact that it is based on the structural group notion. Taking into account its frequent usage in practice in the paper were treated only RRR, RRT and RTR structural groups.
Modeling and Design of Prosthetic Abutment System to Evaluate the Complex Interface
Authors: Rotariu Mariana , Munteanu Florin , Turnea Marius , Arotaritei Dragos
Published: October 2014

The biomechanics of the stump-prosthesis system and of the biphasic interaction between bone and muscle and also between stump and prosthesis belongs to a new interdisciplinary field in which modeling and numerical simulation research is the best solution to capture and investigate particular biomechanical aspects that have a high degree of intra-and inter-individual variability. By means of the reverse dynamics method, during the foot resting on the floor stages, one may thus define the biomechanical models of the anatomic stump-prosthesis system. The solution suggested relies on a set of methods including techniques specific to medical imaging analysis and processing, graphical 3D representation of the anatomic model developed using experimental data and its manipulation for study-related purposes or for later processing.The CAD modeling of the anatomic structures and prosthesis components was done using a series of conventional techniques available in the CAD SolidWorks 2008 and CosmosWorks2008 programming environment. A prerequisite for a successful recovery process is the patient’s availability to get actively involved in a physical therapy program. The monitoring of patients with amputated limbs that leave the hospital and of the complications developed in time in these patients is difficult since some miss their periodic follow-up examinations or are referred to other specialized departments. Therefore, a prediction of the evolution of the diminished functional capacity of patients with amputated limbs by stump-prosthesis system design using the finite element method is much more efficient.
Role of Synovial Fluid Constituents on Tribological Behavior of Synovial Joints - Application for Developing Novel Therapeutic Substitutes
Authors: Sava Mirela Maria , Suflet Dana Mihaela , Berthier Yves , Trunfio-Sfarghiu Ana Maria
Published: October 2014

Joint diseases represent a major health problem because they evolve towards the wear of cartilage for which no treatment is really effective. The difficulties in identifying the causes of these diseases are related to the biochemical and structural complexity of synovial fluid that allow cartilage lubrication. Thereby, recent studies show that synovial fluid contains micro-vesicles filled with a glycoprotein gel (hyaluronic acid and protein) surrounded by stacks of lipid bilayers which gives it excellent lubricating properties [1]. On the other side, this stable structure in vivo, becomes unstable in the ex vivo conditions. In this context, the study aims to tests the lubricating properties of synovial fluid constituents in order to identify their role on the tribological behavior of synovial joints and to develop a biomimetic synovial fluid using self-assembly of polyelectrolytes in order to stabilize the ex vivo structure for the potential therapeutic synovial fluid substitutes.Our results show that the new synthetized polysaccharides influence the friction coefficient, the stability and the wear of lipids bilayers, providing lubricating properties superior to synovial fluid biological constituents. In addition, their capacity to be structured in micro-spheres and included in lipid micro-vesicles indicates them as good biomimetic lubricants. This will allow a longer stability of synovial fluid substitutes in ex-vivo conditions in order to achieve the best lubricating properties and to improve the joint diseases treatment.
The Kinematic Model with Three Degrees of Freedom Associated to the Direct Throwing in Basketball Game
Authors: Iacob Radu , Budescu Emil , Merticaru Eugen , Oprişan Cezar
Published: October 2014

The paper presents a reverse kinematic analysis for the free through to basket in order to determine the possible angular movement speed of the arm segments during throw flexion. The body segments offering three freedom degrees to the kinematic model are: the arm, the forearm and the hand. From geometric conditions regarding to the possibility of the ball to get through the basket and the analysis of the parabolic trajectory of the ball, one could determine the mathematical relations for the limitative values of the horizontal and vertical components of the initial velocity and consequently, for the calculation of the initial angle of throwing the ball. On the other hand, from the expression of the flexion movement of the considered body segments, it could be possible to obtain the calculation of the initial throw velocity as functions of the anthropometric data of the analyzed subject, of flexion angles and angular velocity of movement of the body segments. Using some models of functional mathematic analysis, from the two equations with three unknowns, one could determine the variation field of the system solutions. By setting the conditions related to the numeric limits of variation for the angular speed, the numeric field of the possible solutions for the equation system is straitened.
Experimental Validation of a Finite Element Model of an Osteoporotic Human Femoral Bone Using Strain Gauge Measurement
Authors: Takacs Ioana Alexandra , Dudescu Mircea Cristian , Hărdău Mihail , Botean Adrian Ioan
Published: October 2014

The complications of fractures caused by osteoporosis have a mortality rate of 15-20 % in elderly people, leading to severe physical disability and long term home care [1]. Although currently, the technology that allows us to prevent osteoporosis and fractures caused by this disease exists, the statistics are concerning and can be considered basis for further research regarding this pathology of the bone tissue. This paper aims to address this issue form an engineering perspective by achieving experimental validation of a finite element model of an osteoporotic human femoral bone using strain gauge measurement for an in vitro analysis. A Computer Aided Design (CAD) model based on a CT of a human femoral bone was then used in a numerical analysis. The material constants used are taken from the literature and have been validated experimentally by strain gauge technique.
A Workspace Characterization of the 3-RRR Planar Parallel Mechanism
Authors: Buium Florentin , Leohchi Dumitru , Doroftei Ioan
Published: October 2014

The paper deals with a workspace problem of the 3 RRR planar parallel mechanism, used as parallel robot structure. Depending on the dimensional parameters and constructive characteristics, the authors search to depict the shape and particularities of the mechanism workspace of a 3 RRR planar parallel mechanism. This characterization of the mechanism workspace depending on the dimensional parameters can be usefull in mechanism designing accorded to some functional particularities and also can help in avoiding singular configurations.
Low Cost Device for Experimental Tests of Electrorheological Fluids
Authors: Chetran Beniamin Vasile , Mândru Dan
Published: October 2014

Electrorheological fluids (ERFs) can change their shear stress and shear rate as a function of the electric field intensity thus, such fluids acts as Newtonian fluids, if no electric field is applied and, become non Newtonian fluids if the presence of an electric field. In the last years, a growth interest is manifested for incorporating smart fluids into structures, as clutches or dumpers. The ERFs shear rate and shear stress must be determined at the moment of designing such mechanical structures. The fluids viscosity is studied by aid of commercially available viscosimeters or rheometers, these do not have the possibility to apply an electric field to the studied fluids. The ER fluids must be studied into specific electric field intensity. This paper presents: a low cost experimental rheometer and experimental results obtained form a study of several commercially available ERFs.
Hexapod Locomotion of a Leg-Wheel Hybrid Mobile Robot
Authors: Conduraru Slatineanu Alina , Doroftei Ioan , Conduraru Ionel , Luca Dorin
Published: October 2014

Legged vehicles are more flexible and mobile on difficult terrain, comparing to wheeled robots. Wheels are convenient on flat surfaces or specially prepared surfaces, wheeled vehicles being faster than legged ones. Also, wheeled robots are simpler in terms of mechanical architecture and control algorithms. But they do not perform well on uneven terrain, which is the case in real life, legged robots becoming more interesting to research and explore. This is why hybrid locomotion systems have been developed, in order to exploit the terrain adaptability of legs in rough terrain and simpler control as well as high speed associated with wheels. In this paper some design and kinematic aspects as well as hexapod locomotion of a small hybrid robot are presented.
Odometry Aspects of an Omni-Directional Mobile Robot with Modified Mecanum Wheels
Authors: Conduraru Ionel , Doroftei Ioan , Luca Dorin , Conduraru Slatineanu Alina
Published: October 2014

Mobile robots have a large scale use in industry, military operations, exploration and other applications where human intervention is risky. When a mobile robot has to move in small and narrow spaces and to avoid obstacles, mobility is one of its main issues. An omni-directional drive mechanism is very attractive because it guarantees a very good mobility in such cases. Also, the accurate estimation of the position is a key component for the successful operation for most of autonomous mobile robots. In this work, some odometry aspects of an omni-directional robot are presented and a simple odometer solution is proposed.
Naval Centrifugal Compressor Design Using CAD Solutions
Authors: Dumitrache Constantin , Calimanescu Ioan , Comandar Corneliu
Published: October 2014

Centrifugal compressors of turbochargersoperate in a wide range of rotational speeds, which depends on the load of the supercharged engine. Current designs of turbocharger compressors exhibit high efficiencies accompanied by high flow capacities [1]. Consequences of aerodynamic optimization are high mean stress values in the blades due to centrifugal loading as well as dynamic stresses due to blade vibrations. Blade vibrations in a turbocharger compressor are assumed to be predominantly excited by unsteady aerodynamic forces [2]. These forces are caused by a variety of sources influencing the flow. Examples include the geometry of the flow channel, elbows, the diffuser vanes or struts. Therefore, an understanding of FSI is essential for further design optimizations.
Virtual Planning of Robot Trajectories for Spray Painting Applications
Authors: Girbacia Teodora , Girbacia Florin , Mogan Gheorghe
Published: October 2014

In this paper is presented a Virtual Reality application that can be used for automatic generation of robot trajectories for spray painting operations conducted on products with complex surfaces. The trajectory generation for robots that perform painting operations of complex curved surfaces was achieved by implementing a generic algorithm capable of maintaining an optimal distance for painting. The distance between the effecter of the robot and the surface of the CAD model, used to compensate and maintain an optimal painting distance, is determined by a "rayhit" collision detection algorithm that allows the detection of the contact between a linear segment and the mesh of the virtual object. To visualize in the virtual environment the deposition of paint layers, an algorithm was implemented that is based on mapping techniques for dynamically generated textures on the surface that is being painted. A VR software application was developed for generating and visualizing the trajectories of a KUKA robotic system that performs the activity of painting a complex curved product.
Naval Standard Safety Valve Design Using CAD Solutions
Authors: Dumitrache Constantin , Calimanescu Ioan , Comandar Corneliu
Published: October 2014

Apressure relief valveis a safety device designed to protect a pressurized vessel or system during an over-pressure event. An overpressure event refers to any condition which would cause pressure in a vessel or system to increase beyond the specified design pressure or maximum allowable working pressure. Many electronic, pneumatic and hydraulic systems exist today to control fluid system variables, such as pressure, temperature and flow. Each of these systems requires a power source of some type, such as electricity or compressed air in order to operate. A pressure relief valve must be capable of operating at all times, especially during a period of power failure when system controls are nonfunctional. The sole source of power for the pressure relief valve, therefore, is the process fluid.
Comparative Analysis of the Structures 4R and 3T Robots
Authors: Ocnărescu Constantin , Simionescu Ion
Published: October 2014

A geometric and kinematic study between two structures of robots was performed, respectively a mechanical anthropomorphic structure, with bars and gears, with four degree of freedom, (dof), redundant (4R), which can avoid obstacles and a parallel manipulator with translation on three axes (3T). This 3T structural solution allows rapid and precise movements, which are important characteristics for machine building industry. All these features make the parallel manipulator to be an attractive alternative to the serial ones for high precision operations in a limited workspace.
Finishing System Based on Ultrasonic Computerized Processes for Textiles
Authors: Pantilimonescu Florin , Hanganu Lucian Constantin , Peptanariu Mihaita , Grigoras Stefan , Ionescu Irina , Potop Georgeta Lidia , Iovan-Dragomir Alina , Hanganu Stela Carmen
Published: October 2014

During conventional finishing textile processes it is necessary a big consumption both of water and energy. This aspectsare is imposed by the development process of thermo and mass transfer of finishing agents into the textile structure materials applied in dentistry (fibers, yarns, fabric, nonwovens). The intensification of transfer processes into the textile materials is realized in conventional finishing textile industry (washing, cleaning, and coloring) by using high work temperature. The negative result of this intervention and the presence of chemical substances without degradation mean the environment pollution by the pour out residual water with a great quantity of toxic substances. The recently laboratory scientific research showed that the use of ultrasonic systems in finishing textile materials contributes both to the acceleration of thermo and mass transfer and to the decreasing of active chemical substances. In this way the paper presents a finishing system based on ultrasonic processes which is composed by modules and specific hardware components.
Image Processing and Artificial Neural Network for Robot Application
Authors: Pop Cristian , Grigorescu Sanda Margareta , Lovasz Erwin Christian
Published: October 2014

This paper presents a robot vision application, implemented in MATLAB working environment, developed for feature-based object recognition, object sorting and manipulation, based on shape classification and its pose calculus for proper positioning. The application described in this article, designed to detect, identify, classify and manipulate objects is based on previous robot vision applications that are presented in more detail in [1]. The idea underlying the mentioned applications is to determine the type, position and orientation of the work pieces (in those cases different types of bearings). Taking it further, in the presented application, objects that show shape with a gradual level of complexity are used. For this reason pattern recognition are discriminated by training a two layers neural network. The network is presented and also the input and output vectors.
Improving the Image Accuracy for Grasping
Authors: Spanu Alina , Avram Mihai , Besnea Daniel
Published: October 2014

The paper concerns with a method based on Microsoft Visual Studio for processing the image received from the vision camera working on the gripper of the librarian robot. Based on the information converted from the accurate image, the gripper has to identify the book on the bookshelves. Moreover, the outer edges are the most important due to the working area required by the fingers. Meantime, the method should analyze the outer edge on the top too, so that the gripper should have enough room for working by pushing up the book. We have used the dynamic method for setting aside the computer memory. The image processing was focused on improving the contrast quality due to its importance for setting up the outer edges of the book, which should be retrieved.
Mechanical Characteristics of Electronic Printed Circuit Obtained by the Vapour Phase Soldering Process
Authors: Dumitru Georgiana Ionela , Tudor Andrei , Chisiu Georgiana , Plotog Ioan
Published: October 2014

The goal of the present paper is to describe some mechanical aspects regarding the adhesion of the copper layer deposit on the rigid support of printed circuit boards (PCB) used in electronic technology. In order to highlight the adhesion of the copper layer in correlation with different rigid support, there were performed some micro-scratch tests using a dedicated system. The mechanical strength is obtained by shear test. The paper novelty presents a mechanical experiment which will describe the tribological properties with influence on the reliability of electronic assemblies
Development of the Microrobot for Indoor Pipeline
Authors: Tătar Mihai Olimpiu , Mândru Dan , Jisa Vasile Sergiu
Published: October 2014

Generally the in-pipe microrobots can be used for the mobile inspection of small diameter pipes. This paper describes the structure and design of an in-pipe microrobot. The suggested microrobot was built to use wheels for locomotion, and to be able to adapt its structure according to the inner diameter of the inspected pipe. Being powered using wires, the microrobot is not energetically autonomous. The microrobot is able to maintain its balanced state due to the pressure exerted by the wheels onto the inner surface of the pipe and it can adapt to pipe diameters ranged between 30 an 50 mm. The driving is achieved by using a DC motor with integrated gearbox. Motion transmission from the motor to the drive wheels is done by using three geared transmissions and the contact between the wheels and the pipe wall is continuously maintained trough a torsion springs mounted on the rotational joints of the wheel support elements. The testing of the microrobot was performed using a steel pipe with the diameter of 50 mm, placed both horizontally and vertically.
Validation of the Expert System Used for Optimum Gripping Surfaces Identification for an Injection-Molded Part
Authors: Tocut Pavel Danut , Tripe Vidican Calin , Tarca Ioan Constantin , Bungau Constantin
Published: October 2014

This paper describes a validation method through experimental tests of the Expert System conceived for the identification of the optimum gripping surfaces for an injection-molded part, conceived by the authors. A number of experimental tests were conducted using a flexible vacuum end-effector. During experimental tests phases three different versions have been considered for experimenting in which different types of suction cup holders and different placements on the end-effector structure were analyzed. The part subjected to tests was a stove handle. The first version of the vacuum end-effector is composed of four rigid suction cup, their placement on the gripper being made on points randomly chosen. The second version of the end-effector is composed of four flexible suction cup holders equipped with spherical articulations; the axes adjustment on the gripped surfaces being made on four randomly chosen points. The third version is composed of four suction cup holders equipped with spherical articulations, the axes positions and points placement being offered by the Expert System.
Compounding of Concurential Rotation Movements
Authors: Antonescu Ovidiu , Popescu Ioana , Antonescu Păun
Published: October 2014

By the composing of the rotation movements with the concurrent instantaneous axes in a point, a rotation movement with the instantaneous axis passing through that point is obtained. The resultant instantaneous angular velocity is sum of the component angular velocity. As examples of the mechanical systems in which appear the concurrent rotation movements are: the pivot bearings of the radial-axial with balls type, the ball radial bearings and the planetary mechanisms with bevel gears which are used both as differential to automotives and as orientation mechanisms (wrist) on the industrial robots.