This article presents a study on how to determine the coefficient of friction of solids. Experimental measurements were made on a laboratory bench experimental work using the surface materials used in a block of the site that the braided wire mesh with mesh size variable. Following the experimental measurements there is a proportional variation between the coefficient of friction and mesh size sieve. It also shows that for the same batch of particles coefficient of variation of friction coefficient has values in the range 8.62 ÷ 12.24%.

The objective of this study is to determine a multivariate model able to perform the identification of the tumor stage and of the histopathological type for lung cancer patients, based on predictive environmental and behavioral factors. The database was built by using clinical and personal information about 106 patients with stage III or IV lung cancer and a mean age of 58 years, who were subjected to radiotherapy at the Radiotherapy Department of „Sf. Ap. Andrei” Emergency Clinical Hospital between January and December 2010. The following factors were taken into consideration: work conditions, smoking habits and duration of the exposure to risk factors. Most of the patients (43.33%) have worked in metallurgy for a mean of 27.54 years and 86.67% have smoked for a mean period of 26.92 years. The duration of smoking and the habit of smoking itself were identified by multiple linear regression as the most important predictive factors for tumor stage and for the histopathological type, respectively. Artificial intelligence techniques were used and the results have indicated that tobacco use and the environmental factors related to the work place (e.g. metallurgical industry) are the best predictive risk factors for the incidence of lung cancer.

This paper describes a comparative study of extraction methods such as maceration, pressurized liquid extraction, ultrasound assisted extraction or microwave assisted extraction with different solvents of bioactive compounds from pomaces of four different apple varieties. In order to evaluate their chemical composition the obtained extracts were analysed by High Performance Liquid Chromatography – UV detection – Evaporative Light Scattering Detection (HPLC-UV-ELSD). The study revealed that, while extraction solvent influences the recovery of different compounds, the extraction techniques do not induce selectivity since any major differences of the extracts fingerprints and of the relative proportion of compounds were observed.

The requirements of very high performance (stress, rotational speed, stability to vibrations, etc.) for the compounds of mechanical engineering also involve an adequate fiability. The bearings can run at over 70 m/s peripheral speed of high fiability conditions (gas turbines in the aviation industry), with some high precessions and depressed frictions (gyroscopes, grinding broaches), with low/depressed noise and vibrations level. The increase of the bearings speed over the limits considered “ordinary” influences negatively the durability due to some kinematic, dynamic and lubrication significant changes. Major centrifugal forces appear, friction forces modify sensitively, starvation phenomenon occurs, and vibrations are established, too.

In this paper, it is presented an experimental model, based on strain gauges measurements, used to validate an analytical model for strength calculus of three dimensional hiperstatic structures under static loadings. There will be presented all the experimental apparatus used, and in the end, a particular case will be used in order to estimate the errors between the experimental and analytical model.

This paper reflects the feasibility of a bidirectional wireless communications between remote microcontrollers to form a wireless network. In order to prove this hypothesis, a wireless network including two microcontrollers which use data transmission sub modules will be conceived.

When we analyse the distribution of the heavy metals in urban soil, the unique characteristics of the urban environment are limiting the efficacy of the statistical methods. The paper arguments the necessity of conducting a research project to analyse the distribution of Pb, Cd, Ni, Mn, As, in the soil of Bacau City, Romania and presents the working methods which shall be used.

The purpose of the researches presented in this paper is to make evident the cracking and breaking causes of the 10¾" drill pipes, used for the drilling of the mining shafts which have a diameter of 3.62 m. In this way, the free torsional vibrations of the 10¾" drill string are studied by using the drill string model with non-uniform distributed mass and mass moments of inertia concentrated at the ends. Then, the electro-hydrostatic driving group inertia and the compressibility of the hydraulic medium in the hydrostatic transmission lines are taken into account. It is ascertained that the influence of the hydraulic medium compressibility is unfavorable from dynamic point of view because it decreases the natural angular frequency of torsional vibration in the working speed area of the drill string. The appearance of the resonance phenomenon in this working area is made evident by experimental researches and can be a reason regarding the breaking of the drill pipes assembled in the lower third of the drill string.

This paper presents the energy performances of a pneumatic installation designed to improve the homogenization degree of the mixture consisting in recirculated flue gas and primary air used in pulverized coal combustion. The installation consists in a series arrangement of a centrifugal fan and a side channels blower. The experimental setup is intended to equip the burner of a 2.5 MWh pilot boiler, where the influence of the mixture parameters on the reduction in NOx emissions is studied. The performance curves of the centrifugal fan and those of the side channels blower were obtained experimentally. Based on them, the performance curves of the series arrangement were obtained analytically, in order to assess the variation of pressure depending on the flow rate required by the burner. Of a particular interest was the degree in which the usage of the side channels blower could eliminate the risk of surge typical for centrifugal fans operating at low discharges.

This paper promotes a model for calculating the stress intensity factor at the crack tip in a bi-material composite laminated for damage tolerance model obtained using a brittle material that geometry. The model is based on assumptions about the elastic properties are homogeneous throughout the composite material and using finite element simulations leading to moderate results different from those obtained using the homogeneous model. Also, the model relies on the assumption that the system behaves as a homogeneous anisotropic material and when the field of stress at the crack tip is created on account of the effect of applied loads on crack tip and thus gives results that are closer to those of finite element simulations.

The aim of the current study was to analyze how number of elements of linear array and frequency influence the image quality in a homogenous medium. Linear arrays are most common for conventional ultrasound imaging, because of the advantages of electronic focusing and steering. First, was made comparison for simulated computer phantom with linear array with different number of elements (32, 64 and 128) and 3 MHz frequency. Second, the frequency was changed and the results were compared. Finally the results obtained were interpreted and discussed.

The tendency to use high-capacity pumps especially in power plants raised the need to reduce the leakage flow rate of the mechanical seals and to increase their lifetime. During this study the influence of the geometric shape of the stationary seal ring under the action of the axial forces on the leakage flow rate between the active front surfaces was investigated. Hydrostatic and hydrodynamic measurements were carried out in order to confirm the results.

An object of study is a SrBr2 vapor laser source with its emission at a wavelength 6.45 μm. This type of laser finds applications in medicine and biology. A temperature model, determining the laser medium’s temperature profile under forced convection is used in this study on the basis of quasi-stationary heat conduction equation. It was established that the working temperature can change in a wide range while the airflow velocity changes. Computer simulations that let increase of supplied electrical power for holding optimal temperature in the center of the tube were performed.

In the paper are summarized the major and most often encountered manufacturing errors influence on the stress concentration factor and on the state of stress of the spherical tanks shell, used for the storage of liquefied gases, discontinuous equatorial supported, complex loaded. There are presented stress concentration factor calculus formulas to be used to take into account the welds flaws. The spherical tanks shell is subjected to low cycle fatigue stress, especially due to the extension of the working time period (often encountered in nowadays practice). So it is evaluated the low cycle fatigue strength/number of cycles of the spherical tanks shell both in the absence of fabrication and assembling errors and taking into account these kinds of errors. Here is presented the theoretical approach. Another part will deal with the calculus approach and the conclusions.

Bats use echolocation to navigate their environment, to localize and identify prey. Researchers have proposed ultrasonic biomimetic systems that make use of the way bats echolocate. EMFi is a new material, which has good properties for air. We used this material to construct an ultrasound emitter capable to work in a similar way as bat’s emitter. We did measurements in order to study the far field directivity pattern for an EMFi hemi-cylindrical array with four strips. Experimental studies of the directivity emission in far field for this type of transducer highlighted the capabilities of this emitter.

This paper presents the effect of loading rate, (ELR), and direction of formation, (DF), of rigid polyurethane foams, (PUR 40 and PUR 140), on fracture toughness. Nominal densities of used foams in the experimental program were 140 kg/m3, (for ELS) and 40 kg/m3, (for DF), which is closed-cell rigid foams widely used for sandwich cores. Determination of fracture toughness for Mode I fracture of studied materials has made by three-point bending tests, (3PB), on specimens with notches, at room temperature (20 ± 2 ºC). All the specimens were cut from one and the same plate. The specimens were subjected to 3PB at a loading speed of 2 mm/min, except samples for determining the ELR where 2, 20, 200 and 400 mm/min loading speeds were used, and were taken into account the fact that the load must act exactly on the notch direction. All the specimens present brittle failure without plastic deformation.

he present work concern an experimental study of gas cleaning by a wet venturi scrubber. The water is introduced before the convergent and streams as a liquid along the venturi walls. Hydrodynamics, mass and thermal mechanisms occurring in the venturi tube and the scrubbing process are investigated in detail. Results show that the maximum density of water vapor resulting of vaporization of the liquid film is observed in the venturi throat. In addition, the collect efficiency increases as the inlet gas velocity and the scrubbing liquid flow rate increase.

The current work deals with numerical simulation connected to forming of a rectangular shaped part made from tailored blanks (TWB’s), having the welding line positioned symmetrical with respect to the part geometry. During the deep drawing process, due to dissimilar base materials of the TWB’s, the welding connection modifies its initial position. The presented work is trying to demonstrate the important role of the blankholder force on the welding line movement during the deep drawing process. To simulate the forming process the academically version of the PAM STAM 2G software have been used. After each simulation the obtained part is analysed and measured to quantify the movement of the welding line.

The noise is unwanted information which damages the quality of the ultrasound images. For a high quality ultrasound image the noise should be eliminated. The experimental ultrasound image set contains two images of different phases of cardiac cycle. The quality of the obtained result was assessed using the parameters: SNR (signal noise ratio), PSNR (peak signal to noise ratio), MSE (mean error) and MAE (mean absolute error). The results were compared with those obtained by applying a median filter. The conclusion is that the de-noising of ultrasound images with CWT-DT is more efficient than the median filtering method.

One analyses, for a 1000 mc spherical tank, equatorial supported by 10 cylindrical pillars (which stores propylene at 2.1 MPa), the influence of the different type fabrication and assembling errors on the spherical shell stress concentration factors. First there are presented the calculus results for the welds flaws influences on the stress concentration factor. Afterwards, with the aid of an original MathCAD program, there are calculated the influence of the fabrication errors (local losses of wall thickness, flattening, assembling eccentricities of the supporting system) on the spherical shell state of stress, taking into account a complex loading (working/storage pressure/hydraulic test pressure, wind, hydrostatic pressure, own weight, deformation restraint (due to horizontal forces determined by the temperature difference between working conditions and assembling conditions and also by the seismic loadings) exerted by the supporting system on the spherical shell and loadings due to the supporting system discontinuities). The influences of the two types of errors are then superposed. Finally is calculated the fatigue number of cycles in the presence of all types of errors.