System Of Bar Research Articles

Effect of Aggregate Mix Proportion on Static and Dynamic Mechanical Properties and Pore Structure of Alkali-Activated Slag Mortar with Sludge Pottery Sand

The overexploitation of river sand will reduce the stability of the river. Using sludge pottery sand (SPS) as a substitute for fine aggregate in mortar can reduce the weight of building mortar and achieve pollution control and resource regeneration. Based on the consideration of energy-saving and carbon reduction, the combination of alkali-activated slag cementitious material and SPS with potential pozzolanic activity to prepare sludge pottery sand alkali-activated slag mortar (PSAM) can replace the traditional silicate river sand mortar. The static and dynamic peak stress of PSAM was tested, and the energy dissipation characteristics of PSAM specimens under the dynamic load were analyzed by using the wave acquisition system of a split Hopkinson pressure bar. The results show that the SPS with 0.15~2.36 mm has better mechanical properties. The increase in the mixing ratio with the SPS with 2.36~4.75 mm will gradually reduce the static and dynamic compressive strength of the specimen, and also reduce the density of the specimen. SEM images and binary pore morphology images showed that the increase in SPS size will lead to a large number of coherent pores inside the specimen, which will increase the air content of the specimen, but at the same time reduce the absorption capacity of the specimen to the wave, so the dynamic energy absorption peak of PSAM appears to decrease significantly. The image of ultra-high-speed photography revealed the mechanism of crack propagation of the PSAM specimen. The development of the crack is positively correlated with the dynamic energy absorption performance when the specimen is completely broken.

Investigation of dynamic fracture behavior and energy dissipation of water-bearing coal under impact load

The stability of residual coal pillar in coal mine is significantly affected by the ponding in goaf and the dynamic disturbances such as blasting vibration and mine tremor activity in the production process of surrounding coal mines. In this paper, the effects of different loading pressure and water-bearing state on the dynamic fracture mechanical properties and energy dissipation law of coal samples were studied. The dynamic fracture characteristics of dry, natural and water-saturated notched semi-circular bending (NSCB) coal samples were tested under different loading pressure by using the impact loading system of split Hopkinson pressure bar (SHPB). A high-speed camera was used to record the dynamic crack propagation process. Combined with image processing method and fractal dimension calculation software, the influence of loading pressure and water-bearing state on fractal characteristics of crack propagation in coal specimens was further analyzed. The results show that at the beginning of crack initiation, water-saturated coal samples are easy to fracture compared to dry and natural coal samples. During the crack propagation, the dry and natural coal samples have a shorter crack penetration time compared to the water-saturated samples. The fracture toughness of the saturated coal sample is sensitive to the loading pressure and there is a threshold value. When the loading pressure is lower than 0.483 MPa, the dynamic fracture toughness of the dry coal sample is greater than the saturated coal sample. While the loading pressure is higher than 0.483 MPa, the dynamic fracture toughness of the saturated coal sample is greater than the dry coal sample. The fractal dimension of the crack propagation path of the coal sample changed as a “V” shape with the loading pressure. The fractal dimension of the crack propagation path of the dry coal sample is always higher than the water-saturated coal sample. The fracture energy of the coal sample meets the y=a·bx exponential growth relationship with the loading pressure. The fracture energy of water-saturated coal sample is the largest and the natural state is the least during the fracture process. The research results can provide theoretical guidance for the stability assessment of residual coal pillar as well as the safe and efficient mining of deep coal resources.

Design of Electromagnetic Control of the Needle Gripping Mechanism

This paper deals with the modification of the mechanical system of the needle bar. The purpose of this work is to reduce the vibration and noise of the sewing machine for creating a decorative stitch. A special floating needle is used to sew this stitch, in which two mechanical systems of needle bars handover through the sewn material, so that a perfect imitation of a hand stitch is created. The original system, which controls the release of the needle at the handover location by abruptly stopping the needle bar control element, could be replaced by a new system that uses magnetic force to release the needle. In addition to the usual design procedure, numerical simulations of the attractive force of the electromagnet are also used in the design of a suitable electromagnet. At the same time, an electrical circuit is also designed to allow the needle to be released and gripped quickly. The advantages of the new system lie not only in reducing vibrations and the associated increase in the operation speed of the machine, but also in making it easier for the machine to switch to possible automated or semi-automated production.

LEGITIMACY OF ADVOCATES RELATED TO THE COURT EXAMINATION PROCESS

Court examination in Indonesia, particularly on the first and second stage, works on examining facts of a disputed case. Ideally, the Judge’s decision is made based on consideration about the case. However, one case showed that the legitimacy of the advocate team that worked on that case, interfere the Judge consideration and changed the result of the examination. The problem was, the presumed illegitimate advocate was made based on a vast-changing law about advocate. Indonesia experienced several change from multi-bar to single-bar and to multi-bar system of advocate bar. The question of the legitimacy of the advocate on that case was based on that unfortunate condition of the bar system, not because of the neglect performed by the advocates themselves. This led to a question on how the procedural aspect like the legitimacy of advocate could affect the material aspect, which is the on-going case and resulted to a different verdict.

Investigation of chatter stability of cutting process with a rotating tapered cutter bar considering internal and external damping

The damping of cutting system is an important factor influencing stability in boring and milling process. However, systematical and thorough studies of the influencing mechanism of damping, especially on the chatter stability of rotating cutter bar, are still absent. The damping of a cutting system mainly consists of external damping and internal damping. This study focuses on these damping effects on chatter stability of the cutting system with a rotating tapered cutter bar. The partial differential equation of motion of the cutter bar is derived based on the Hamilton principle combined with the Euler-Bernoulli beam theory. It is assumed that the cutter bar is tapered, and its free ends acts on a two-dimensional regenerative cutting force with time-delay effect. The damping mechanisms of external and internal are described by the viscous damping model and the strain-rate-dependent Kelvin-Voigt model, respectively. The partial differential equation of motion is discretized as an ordinary differential equation using the Galerkin method. The Campbell diagram and the decay rate plots including critical rotating speed and instability threshold of the cutter bar are obtained by free vibration analysis. Also, the chatter stability lobes in the cutting process are plotted and the predicted results of stability in frequency domain are compared with those in time domain. The results indicate that the structural parameters of a cutter bar, including the rotation, the ratio of internal and total damping, damping ratio, and taper and aspect ratios have significant effects on cutter bar dynamics and chatter stability of cutting process. In particular, a new chatter instability is observed for the cutting system in higher rotating speed ranges due to the effects of rotation and internal damping. The onset rotating speed of the new chatter instability equals to the instability threshold of rotor system of cutter bar. Finally, the present model is validated by comparing both stability prediction given by previous study and natural frequencies and decay rates by ANSYS FE code.

Experimental Investigation of the Spatial and Temporal Evolution of the Tangential and Normal E-Field Components along the Stress Grading System of a Real Stator Bar

This paper presents results based on direct experimental measurements of tangential (Et) and normal (En) E-field components along the stress grading system (SGS) of a real stator bar (Roebel type) for different AC 60 Hz applied voltages. These measurements were made with a new electro-optic system allowing for the study of both spatial distributions of two E-field components along the bar and their temporal evolution at critical points. The results obtained allowed us to calculate the correlation between the distribution of En and Et along the SGS. In particular, it was demonstrated that the En distribution presents a characteristic minimum, which can be used to identify the zone of partial discharge inception. Moreover, it was possible to observe an enlargement of the Et component distribution followed by a saturation in magnitude with the applied voltage increase. Moreover, the results have demonstrated that the waveform of the En component is mostly affected by the SG material used, producing a greater distortion in its waveform than those obtained for the Et component. The more significant distortion was obtained at the end of the outer corona protection (OCP) material, corresponding to the first maximum of the En component and characterized by the appearance of a third harmonic of large amplitude.

Development and implementation of an automated system of optimal bar cutting at the mill 370/150 at OJSC «BSW – Management Company of the Holding «BMC»

The actual problem of production of long products in bars at the current production of mill 370/150 of OJSC «BSW – Management Company of the Holding «BMC» is considered, a brief technological model of obtaining long products in bars is given, an algorithm for determining the optimal cutting of long products is developed. The developed algorithm will help to reduce the cost of production per one ton and increase the competitiveness of the company’s products. The mechanism of formation of rods of non – dimensional length, which in turn significantly affect the consumption coefficient of metal in production, is revealed.

Deflection Sliding Mode Control of a Flexible Bar Using a Shape Memory Alloy Actuator with an Uncertainty Model

This paper presents a penalty-based sliding mode control (SMC) law for flexible bar system, which uses shape memory alloy (SMA) as actuator. SMA actuators are lightweight, compact and flexible which facilitate their integration into flexible structures. The proposed control law manipulates SMA current to exert the necessary force for deflecting the flexible bar into the desired state. Numerical simulations demonstrate that this new method can control the one-input, multi-output under-actuated system of the flexible bar efficiently. The mathematical model of the flexible system is obtained using physical discretization. The bar is modeled as a combination of rigid rods connected by joints without elasticity and friction. This model demonstrates the flexibility of the system in an effective way. The numerical simulation illustrates the feasibility of the proposed model for analyzing the oscillations of the system and the effectivness of proposed control algorithms.

Development of landslide sign detection using longitudinal vibration mode of elastic bar is subjected to ground soil elastic force

In this paper, the landslide sign detection sensing method is proposed. First, the requirement definition is conducted based on survey result of conventional detection technology. As the result, importance of internal state estimation of soil status is pointed out. Furthermore, active sensing method based on longitudinal vibration mode of elastic bar subjected to ground soil elastic force is proposed in order to realize the internal state estimation of soil status. Moreover, the prototyping of active sensing system of elastic bar is conducted. The system is composed from elastic bar, vibration speaker, acceleration sensor and data logger. The laboratory experiment of vibration mode visualization is conducted in order to decision of vibration diagnosis mode. As the result, the vibration diagnosis mode is selected. Mode shape of the vibration diagnosis mode is derived from longitudinal mode of elastic bar.

Experimental Study of the Dynamic Tensile Mechanical Properties of a Coal Sandstone Disc with a Central Hole

Deep mine rocks are often subjected to rock burst induced by dynamic load. The existence of initial holes will reduce the mechanical properties of rocks and affect the stability and safety of the tunnel excavating. In order to study the effect of the ratios of inner and outer diameter on disc specimen dynamic mechanical properties and failure modes, we use cylindrical sandstone specimens of Φ50 × 25 mm to process center holes of different diameters, and a series of dynamic splitting test were carried out with a system of split Hopkinson pressure bar (SHPB) with the diameter of Φ50 mm when the pressure is 0.15 MPa, 0.3 MPa, and 0.5 MPa. The results show that (1) the dynamic tensile stress‐time‐history curve exhibited double peak phenomena, and the second peak value is less than the first peak value, (2) the dynamic tensile stress peaks decrease nonlinearly with the increasing of the ratios of inner and outer diameter, and the dependence is more obvious when the pressure is higher, and (3) there is a tensile crack running along the loading direction in the failure modes of the five samples with the ratio of inner to outer diameter under three kinds of impact pressure. Under the same impact pressure, when the ratio of inner diameter to outer diameter is greater than the critical ratio of inner diameter to outer diameter, there is an obvious empty hole effect; that is, the sample develops secondary tensile cracks that develop from the upper and lower ends of the pore disc to the center of the inner hole. With the increase of the ratio of inner diameter to outer diameter, the width of the penetration crack increases. With the increase of impact pressure, the critical ratio of inner diameter to outer diameter decreases gradually. The research results have certain significance for understanding the mechanical properties of porous rocks.

Effect of normal annealing and solution temperature on the microstructure and properties of TC4 bar

The engine is one of the core components of aircraft, and the demand of mechanical properties of its raw materials is higher. The microstructure and properties of the raw materials could be improved by optimizing heat treatment systems. In this paper, the effects of annealing and solution aging on tensile properties of TC4 bar were compared, and the effect of solution temperature on microstructure and tensile properties of bar were studied. The results show that compared with annealing treatment, the tensile strength of bar is improved by 80MPa after solution aging treatment. And with the increase of solution temperature, the content of primary α phase is decreased, the content of secondary α phase is increased, the tensile strength is increased, and the maximum value reaches 1093MPa. Finally, it is determined that the heat treatment system of bar is ℃， ℃， 965 /1h WQ+720 /2h AC.

Surface potential measurement of model stator bar with stress grading system by field sensor

This paper proposes a novel method for measuring the potential distribution along the stress grading system of a model stator bar whose voltage is over several tens kV. The technique uses a Pockels field vector sensor by introducing an inverse calculation process from the measured field profile to the potential profile on the measured stator bar. With this system, a potential distribution along a model bar under 50 kVp, 50 Hz voltage is successfully measured. In principle, it is possible to estimate the potential either by measuring the horizontal or vertical component of the field. The utilization of the vertical component is preferable in measuring a model bar due to robustness against optical alignment errors. Through the potential distribution measurement of the model bar, although the maximum value of the electric field increases slightly with the applied voltage, it is confirmed that the electric field grading function was working due to the non-linear resistive material.

More Than Bar Codes: Integrating Global Standards-Based Bar Code Technology Into National Health Information Systems in Ethiopia and Pakistan to Increase End-to-End Supply Chain Visibility.

The United Nations Population Fund (UNFPA) and the United States Agency for International Development (USAID) DELIVER PROJECT work together to strengthen public health commodity supply chains by standardizing bar coding under a single set of global standards. From 2015, UNFPA and USAID collaborated to pilot test how tracking and tracing of bar coded health products could be operationalized in the public health supply chains of Ethiopia and Pakistan and inform the ecosystem needed to begin full implementation. Pakistan had been using proprietary bar codes for inventory management of contraceptive supplies but transitioned to global standards-based bar codes during the pilot. The transition allowed Pakistan to leverage the original bar codes that were preprinted by global manufacturers as opposed to printing new bar codes at the central warehouse. However, barriers at lower service delivery levels prevented full realization of end-to-end data visibility. Key barriers at the district level were the lack of a digital inventory management system and absence of bar codes at the primary-level packaging level, such as single blister packs. The team in Ethiopia developed an open-sourced smartphone application that allowed the team to scan bar codes using the mobile phone's camera and to push the captured data to the country's data mart. Real-time tracking and tracing occurred from the central warehouse to the Addis Ababa distribution hub and to 2 health centers. These pilots demonstrated that standardized product identification and bar codes can significantly improve accuracy over manual stock counts while significantly streamlining the stock-taking process, resulting in efficiencies. The pilots also showed that bar coding technology by itself is not sufficient to ensure data visibility. Rather, by using global standards for identification and data capture of pharmaceuticals and medical devices, and integrating the data captured into national and global tracking systems, countries are able to lay the foundation for interoperability and ensure a harmonized language between global health stakeholders.

Simulation of Tsunami Runup in the Tone River Using Generalized Coordinate System and Influence of River Mouth Bar on Tsunami Water Level

ABSTRACT Nikaido, R.; Aoki, S.; Tamura, H., and Jinbo, M., 2016. Simulation of tsunami runup in the Tone River using generalized coordinate system and influence of river mouth bar on tsunami water level. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 28 - 32. Coconut Creek (Florida), ISSN 0749-0208. This study simulated the tsunami runup in the Tone River using generalized coordinate system and discussed influence of river mouth bar on tsunami water level. This simulation focused on the 2011 off the Pacific Coast of Tohoku Earthquake Tsunami. Numerical simulation of the 2011 Tsunami runup in the Tone River and comparison of the results with the field data showed that the model using generalized coordinate system gave more accurate results than the model using the Cartesian coordinate system. This may be because the configuration of the curved riv...

Potential distribution on stress grading of inverter-fed rotating machines under DC biased voltage

The erosion of the stress grading system of converter-fed rotating machines may occur by partial discharges and heat generation. There remain unclear issues in the formation of the potential and temperature distributions along the stress grading system of coils. In this paper, the potential distributions on the stress grading system of the model coil bar are measured under the application of 1 kHz square wave voltages of 10 kV in peak to peak value with/without 5 kV DC biased voltage. It turns out that DC bias voltage has little effect on potential distribution on a coil surface.

Dynamic deformation of soft soil media: Experimental studies and mathematical modeling

A complex experimental-theoretical approach to studying the problem of high-rate strain of soft soil media is presented. This approach combines the following contemporary methods of dynamical tests: the modified Hopkinson-Kolsky method applied tomedium specimens contained in holders and the method of plane wave shock experiments. The following dynamic characteristics of sand soils are obtained: shock adiabatic curves, bulk compressibility curves, and shear resistance curves. The obtained experimental data are used to study the high-rate strain process in the system of a split pressure bar, and the constitutive relations of Grigoryan’s mathematical model of soft soil medium are verified by comparing the results of computational and natural test experiments of impact and penetration.

Modal Analysis of Two Wheels Scooter Based on Solidworks

Based on Solidworks software, the three-dimensional model of two wheels scooter is set up. The finite element model of two wheels scooter is generated. Modal analysis of driving system and telescopic mechanism of bar on two wheels scooter is investigated. The first five orders natural frequency and major modes of driving system and telescopic mechanism of bar are clarified. The method and the result can be used as a reference of dynamic design and lay foundation for calculation and analysis of dynamic response for the two wheels scooter.

Dynamic Responses of Red Sandstone with Fluid-Solid Coupling under Impact Loading

The research object presented in this paper is coupling effect of porous red sandstone which is more frequently encountered. And this paper use the test system of Split Hopkinson Pressure Bar (SHPB) to survey the impact test action of different porosity red sandstone in different coupling medium in order to obtained the dynamic waveform of fluid-solid coupling red sandstone under impact loading using theoretical analysis and laboratory data. The paper analyzes the impact of porosity, coupling medium on the dynamics characteristics of red sandstone. Based on the experiment study of different coupling medium red sandstone under cyclic impact loading, this paper discussed the dynamic characteristics law of porous sandstone under cyclic impact loading and analyzed theoretically the mechanism of coupling medium under cyclic loading. Porosity has a great influence on dynamic performance of red sandstone. Coupling medium has certain influence on the dynamic characteristics of red sandstone. All those conclusions laid a theoretical foundation for practical application.

The Research of Automobile Automatic Stabilizer Bar Control System and Test Platform

In connection with the problems that the automobile passive stabilizer bar can’t reflect the road conditions in real time and it is difficult to simultaneously meet the requirements of ride comfort and manipulation stability, this paper describes a kind of control system and test platform of the automobile automatic stabilizer bar. The control system uses speed sensor, steering angle sensor, roll angle sensor, lateral acceleration sensor and displacement sensor to simulate a variety of vehicle’s real driving conditions in the laboratory environment. According to the formulated control strategy, the microcontroller will send different instructions to make the executive mechanism act reasonably and in time. Then the test platform is established in the laboratory environment by the method of semi-physical simulation. The system can be designed according to the different needs of the vehicle and ensures the vehicle’s safety and comfort to the maximum.

Are circumnuclear (starburst) rings important in the evolution of the central kiloparsec?

Circumnuclear starburst rings are effective barriers against gas inflow. The large 'pile-up' of gas leads to distinct star forming events in the rings of NGC 5248 and NGC 6951. In our work, the rings are distinctly seen as the locations where the bulk of the central kiloparsec star formation in the last 2 Gyr has taken place. This in turn has direct implications for the large scale bars that have driven the formation of the circumnuclear rings in these galaxies. They have to be at least as old. The system of large-scale bar and circumnuclear ring has therefore ample time to stop gas inflow on the scale of the last 100 pc. The stars formed in the ring will help build the (pseudo-)bulge and eventually alter the gravitational potential.