Papers by Keyword: Pitch

Abstract: The work addresses the issues of increasing processing accuracy and productivity by controlling technological connections that act during the formation of shaped surfaces by grinding and plastic deformation, presents the main indicators of the quality of teeth on the working surface, provided by the developed technology, with a decrease in the maximum value of the actual cutting depth by more than 1.5 times when grinding toothed surfaces by copying, determined influence of the position of the workpiece on the accuracy of the pitch and half-angles of the profile for rolling threads of high precision by radial feed, the purpose of which is movement and measurement, design features determined of rollers for thread rolling on workpieces with low rigidity with tangential feed, the parameters of their threads, including the functional and structural relationship of the helix angles with the dimensions of the rolled thread.

Abstract: The article is devoted to the study of destructibility of the annealed anode paste of different composition in the CO₂ current. It is shown that the destructibility of CO₂ current of petroleum coke is much less than that of pitch coke. The comparison of the qualitative characteristics of the anode paste on the basis of pitch coke and petroleum coke revealed the advantage of petroleum coke, due to its low sodium content. The average destructibility of the anode paste on the basis of different grades of cokes in the CO₂ current is determined. The conducted semi-industrial tests were in good agreement with the laboratory studies.

Abstract: The article is devoted to the study of the impact of technological features of the anode paste production on one of the technical-and-economic indices – its consumption. It is shown that the prior thermal preparation significantly affects the quality characteristics of pitch and petroleum cokes. The comparison of pitches of foreign and homeland producers revealed the advantage of the last because of their small ash content and the lowered content of sodium. Granulometric composition of the dry mix is determined on the basis of different coke brands. They are close to the concentrations of fractions regulated by the technology of production of the anode paste. The conducted semi-industrial tests were in accordance with the laboratory studies and confirmed the fact of reducing the consumption of the anode paste when using the petroleum coke as a filler.

Abstract: High-carbon substances and carbon itself are important structure-forming elements. Of special interest are substances obtained from petroleum feedstock by means of high-temperature treatment. Such substances could include bitumen, pitch, coke, fullerenes, carbon nanotubes and some composition materials. The present article provides a literature review, devoted to structuring in complex multi-component systems, which demonstrated to obtain quasi-crystalline substances in macroscale. In petroleum disperse systems the regulating factor leading to the formation of hierarchy structures is presence in the medium of asphaltenes exerting paramagnetic properties. It was experimentally showed that change of the equivalence ratio of such components as core, salvation shell, and dispersion medium leads to intentional obtainment of various configurations of quasi-crystalline systems. Understanding of macrostructures formation mechanisms under condition of change of medium properties at nanolevel allows constructing new carbon-based constructional materials.

Abstract: ESOUNDMAPS is an ongoing research program that aims in developing a wireless audio sensor network (WASN) and deploying it at the surrounding environmental area of the Technological Institute of Piraeus in Attica, Greece. The proposed WASN will be used for the environmental monitoring of the area and aims to be used in the future for assessing the impact of human generated noise to the wildlife. Collected sound samples will be forwarded by the sensor nodes to a central server where they will be automatically evaluated with respect to their identity; environmental sound maps will be generated based on the evaluation of these sound samples. High-level sound classification is defined herein as the act of classifying a sound sample to three broad categories namely anthropogenic, biophysical (other than human) and geophysical sounds. In this paper we present an integrated platform that includes sound sample denoising using wavelets, feature extraction from sound samples and Gaussian mixture modeling of these features, and a powerful two-layer neural network classifier for the automated high-level classification of incoming sound samples. Classification results, obtained using digital sound samples, exhibit outstanding classification accuracy (sometimes reaching or exceeding 98% correct vs. incorrect estimates), thus demonstrating the feasibility of the proposed approach in realistic environments.

Abstract: As a new type of vertical take-off and landing unmanned aerial vehicles, four-rotor unmanned aircraft has strong load capacity, simple structure, flexible operation Characteristics, so it is the preferred method of execution the air, and is widely used in military and civil field. Based on four-rotor aircraft structure and movement theory, this paper designs the aircaft control system based on ARM. Based on upper machine, the design of PID control algorithm was tested in this paper. From the results, the stability of the controller is good, and its speed control is superior to the single closed-loop.

Abstract: In the present work of experimental investigation, the heat transfer performance of Spiral Tube Heat Exchanger (STHE) is studied by manufacturing the heat exchanger. STHEs are known as excellent heat exchanger because it is compact in size and having high heat transfer ability. The STHE consists of copper coils in the spiral shape and placed inside the shell which is made of Stainless Steel. The spiral shape coil is made by bending the straight copper tube of 10 mm inside diameter. The heat exchanger uses 3 such spiral coil brazed with straight header tube of 25 mm inside diameter and at a distance of 15mm apart, the number of turn in a spiral coil is four. Pump is used for circulation of water in both circuits. Cold water is circulated through spiral coil which entered at the periphery and comes out from centre; hot water is entered at the bottom centre of shell and comes out from the top of the shell. The inlet temperature range of hot water and cold water is 50 to 80°C and 30 to 48°C. Mass flow rate range of hot water and cold water is from 0.0633 kg/s to 0.0833kg/s and 0.01 kg/s to 0.0833kg/s.

Abstract: Four-Legged walking robot is mechanically modeled by copying mammals, which have 13 links and 12 joints. But mechanical models are more on technical rather than on biological concepts, which yield unstable locomotion with low speed. Advanced biological locomotive phenomena and their structural characteristics are applied to the mechanical model and simulated for the one cycle. Torques at joints are calculated and finally converted to total consumed energy. Variables, specifying structure and locomotion, are applied to the simulation as a time function, and the optimal variables which minimize energy expenditure are derived which can be directly applied to the Quadruped locomotion.

Abstract: The defects of the lower tooth height and of larger pitch in thread portion of rolled pieces are prone to appearing when rolling thread shaft in cross wedge rolling. To solve this problem, changing the blank shape and size were tried. Two types of concave conical and round blanks are designed with concave conical blanks obtained by rolling in the cross wedge rolling. Because the design of the rolling die is simple, good precision of blank can be ensured. Multiple size types of blanks were designed and the rolling experiment was made in the rolling mill of model H630. By measuring the values of the tooth height and pitch, the effect of blank shape on thread shafts rolled in the wedge rolling were investigated carefully. The reasonable size range of the blank shape was obtained. The conclusions above pave the theoretical foundation for the in-depth study on this technology.

Abstract: Living creatures can walk or run more elegant and advanced than any other legged mechanical models. Principles of existing robot systems are based more on technical rather than on biological concepts, yielding unstable locomotion with low speed. In order to apply advanced biological phenomena to the mechanical model, three types of vertebrates are selected, and their structures are modeled by 13 links and 12 joints, covering all existing leg and body arrangements, which is a rigid multi-body system and simulated to obtain optimal conditions by calculating locomotion efficiency, which satisfy the principle of minimum energy expenditure.