Improving the quality of surface in polishing process with the magnetic abrasive powder polishing (MAPP) by use of ultrasonic oscillation of work-piece on a CNC table

In this research work, polishing inside, outside and over the cylindrical parts has been done by using a completely new and innovative method. The work-pieces have been placed on a two-axis Cartesian CNC Table for polishing operations. The Magnetic Rotary Head continuously changes its rotation direction from CW to CCW and CCW to CW and meanwhile the part begin to oscillate up-and-down under a High Frequency (20 kHz) conditions. The Frequency of changing direction From CW to CCW and CCW to CW is one of the important parameters in this method. This method is a kind of Ultrasonic Assisted Polishing (UAP) and novelty of this research work is combining this method with motion of work piece under CNC trajectory with continuously changing direction of Magnetic Rotary Head. Gap between Rotary Magnetic Polishing Head and the Work piece Surface can be controlled by a power transmission screw which operates in the direction of the vertical axis. Several experiments have proved high performance of this new proposed method in the process of polishing in short times.     

An experimental study on the tensile properties of atmospheric ice

The intrinsic problem of formation and accumulation of atmospheric ice on structures, such as power electric transmission lines and communication equipment, has in recent years resurrected much interest. However, the mechanical properties of the accreted atmospheric ice are not abundantly recognized and, therefore, analytical modeling of circumstantial material is not conceivable. For this purpose, an experimental investigation into the mechanical behavior of atmospheric ice in uniaxial tension has been conducted using conditions generally favorable to brittle fracture and microcracking. The atmospheric ice is grown from supercooled water droplets impinging on an aluminum cylinder rotating at 1 rpm in the test section of the closed-loop wind tunnel. Ice tensile strength was measured as a function of test temperature varying from − 5 to − 15 °C, wind speed during accumulation varying from 10 to 20 m/s, and strain rate ranging from 2.22 × 10^− 6 to 1.67 × 10^− 3 s^− 1. The details of specimen preparation, testing procedure and strength test results are discussed. The fracture mechanism for atmospheric ice is also discussed, and the test results are compared with data reported by previous investigators. A mathematical model was developed using Minitab-15 software to predict the effect of ice accumulation conditions on the tensile strength. Detailed analysis indicates that the interaction coefficients of these variables do not appear to contribute significantly to the tensile strength of atmospheric ice.     

Surface modification of commercial carbon black by silane coupling agents for improving dispersibility in rubber compounds

The dispersion of a filler in a rubber matrix is a crucial parameter affecting the mechanical and dynamical properties of a rubber compound. It is the current issue of the rubber compounding industry because, most fillers are categorized as a mineral, while the rubber is an organic material. The surface modification of the filler has been accepted as an effective technique for the improvement of the abovementioned parameter. First, the surface premodification of commercial carbon black with a grade of N660 (CB) was implemented by four different oxidation methods. After that, among of used methods, the oxidation method using citric acid was selected to produce modified carbon black (CB-Oxi) for further treatment. Subsequently, the coupling agent, Bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) was functionalized on the surface of CB-Oxi to produce modified-CB-Oxi. Also, for comparison purposes, the TESPT functionalization was accomplished on untreated CB to form modified-CB. The FTIR spectra of CB-Oxi showed using the premodification method introduced the hydroxyl and carboxyl groups on the surface of CB. The correspondent spectra for modified-CB-Oxi confirmed the existence of silane groups on the surface of the carbon black. However, the mentioned silane groups were not observed on the surface of modified-CB. The findings were strengthened by several characteristic techniques including, FESEM, XRD, EDS, CHNS elemental analysis, and RAMAN spectra. The FESEM graphs and elemental mapping showed homogeneous dispersion and uniform distribution of sulfur and silicon elements on the modified-CB-Oxi surface. According to RAMAN spectra, the disturbance in the structure of carbon black graphite was reduced after surface modification. modified-CB-Oxi is proposed as a potential substitute filler for current commercial carbon black in rubber compounding.     

Nanosecond streak photography of discharge initiation on ice surfaces

This paper presents an exploratory experimental study of discharge initiation on surface of ice. The phenomena underlying these processes are, as yet, poorly understood. To elucidate the initiation process in particular, ultra high-speed streak photography was used to observe and analyze the first visible discharges and a number of parameters were investigated. It could be shown that ambient temperature, conductivity of ice surface and the presence of imperfections on the ice surface influence not only the critical voltage for discharge initiation, but also the velocity of discharge development. Some parameters could be identified, which should be investigated further. The present paper is the first stage of a long-term research effort in this new field. This study should enable further experimental investigations and mathematical simulations to gain better understanding of ice surface discharges, specifically in the context of electrical insulation integrity of support insulators in power systems operating under severe atmospheric conditions.     

Specific investigations to quantify heavy damage causes on loading resistor modules

In this paper, premature damage to some static inverter loading resistor modules is analyzed. Furthermore, investigations were carried out to determine the origins and causes of this serious damage occurring on the resistor modules in service. Investigations were preformed on the insulating liquid samples as well as new resistor modules. From the results obtained, it seems that the origin of the damage is from a long-standing, free-burning arc between two resistor windings, following mechanical breakdown.     

Characterization and amino acid sequence of the OXY-2 group beta-lactamase of pI 5.7 isolated from aztreonam-resistant Klebsiella oxytoca strain HB60

EPA's Risk Assessment Guidance for Superfund (RAGS) and later documents provide guidance for estimating exposures received from suburban and agricultural activity patterns and lifestyles. However, these methods are not suitable for typical tribal communities whose members pursue, at least in part, traditional lifestyles. These lifestyles are derived from a long association with all of the resources in a particular region. We interviewed 35 members of a Columbia River Basin tribe to develop a lifestyle-based subsistence exposure scenario that represents a midrange exposure that a traditional tribal member would receive. This scenario provides a way to partially satisfy Executive Order 12,898 on environmental justice, which requires a specific evaluation of impacts from federal actions to peoples with subsistence diets. Because a subsistence diet is only a portion of what is important to a traditional lifestyle, we also used information obtained from the interviews to identify parameters for evaluating impacts to environmental and sociocultural quality of life.     

Stoffaustausch zwischen flüssigem Eisen und Schlacke beim Sprühraffinationsverfahren

Erläuterung des Sprühraffinationsverfahrens, bei dem eine Schmelze mit inertem Gas verdüst wird und die entstehenden Metalltropfen durch eine Raffinationsschlacke fallen. Erörterung der Gesetzmäßigkeiten für die Stoffaustauschvorgänge zwischen Metalltropfen und Schlacke. Bestimmung der mittleren Tropfengröße beim Versprühen von kohlenstoffgesättigtem Roheisen. Untersuchung der Wirkung der Sprühraffination am Beispiel der Entschwefelung des Roheisens mit Schlacken des Systems CaO–CaF₂–Al₂O₃ bei 1600 °C. Ermittlung des Stoffübergangskoeffizienten des Schwefels für den umgekehrt transitorischen Phasenkontakt und Vergleich mit Werten bei anderen Techniken des Phasenkontaktes Metall-Schlacke.     

An experimental investigation of cylindrical wire electrical discharge turning process

The cylindrical wire electrical discharge turning (CWEDT) process was developed to generate precise cylindrical forms on hard, difficult to machine materials. A precise, flexible, and corrosion-resistant submerged rotary spindle was designed and added to a conventional five-axis CNC wire electrical discharge machine (EDM) to enable the generation of free-form cylindrical geometries. The hardness and strength of the work material are no longer the dominating factors that affect the tool wear and hinder the machining process. In this study, the effect of machining parameters on surface roughness (R _a) and roundness in cylindrical CWEDT of a AISI D3 tool steel is investigated. The selection of this material was made taking into account its wide range of applications in tools, dies, and molds and in industries such as punching, tapping, reaming, and so on in cylindrical forms. Surface roughness and roundness are chosen as two of the machining performances to verify the process. In addition, power, pulse off-time, voltage, and spindle rotational speed are adopted for evaluation by full factorial design of experiments. In this case, a 2²?×?3² mixed full factorial design has been selected considering the number of factors used in the present study. The main effects of factors and interactions were considered in this paper, and regression equations were derived using response surface methodology. Finally, the surfaces of the CWEDT parts were examined using scanning electron microscopy (SEM) to identify the macro-ridges and craters on the surface. Cross sections of the EDM parts were examined using the SEM and microhardness tests to quantify the sub-surface recast layers and heat-affected zones under specific process parameters.     

Effects of cold plasma on the color parameters of Hyssop (Hyssopus officinalis L.) using color imaging instrumentation and spectrophotometer

This research was conducted to evaluate the effects of cold atmospheric plasma treatment on the color of Hyssop (Hyssopus officinalis L.) and also to compare the usage of the spectrophotometer vs the color imaging instrumentation for the evaluation of the treatment on the color parameters. The experiments were investigated at different treatment times of 1, 5, and 10 minutes and the voltage values of 17, 20, and 23 kV. Possible changes of color were evaluated by using CIE L*a*b* values obtained with HunterLab colorimeter and CIE L*a*b* values obtained with a digital still camera (DSC) using digital image processing (MATLAB software). The values of L*, a*, and b* of the samples were obtained using both the methods. The results revealed that the L*, a*, and b* values of the treated Hyssop samples changed with increasing the treatment time and the voltage applied. Evaluating the interaction effects revealed that there was a significant difference in the (−a^*/b^* ) ratio. In addition, the results showed that the effects of all variables on the color parameters were significantly different in the case of the DSC using digital image processing. However, these effects were not significantly different using HunterLab colorimeter except for time variable and interaction effects of a* and (−a^*/b^* ) ratio. The lightest green color and the maximum chlorophyll content loss were observed for 23 kV applied over 10 minutes. Based on the results, the digital image processing can be used as a practical tool to study the variations at the color of dried Hyssop leaves after cold plasma treatment.