Dynamic Balancing Method Research Articles

Development and Experimental Study of the Online Dynamic Balance System for Grinding Machine

The vibration of grinding wheel spindle will significantly reduce the machining quality and machining accuracy of precision grinding. In order to suppress the grinding wheel rotor vibration effectively, the Spray-Typed online dynamic balance system for specific grinding wheel spindle was designed composed of terminal balance, hydraulic system and control system. To achieve the amount of spindle unbalance accurate extraction and liquid volume control, using hydraulic system to achieve the balance of the terminal of the liquid loading and using high-performance DSP chip as a control method. A segmented spindle online dynamic balance method , combining the advantages of influence coefficient method and coordinate rotation optimization method was proposed. The method can fast approaching the goal of balancing and meet the local precise adjustment of the balance weight. At last, the online dynamic balance experiment of grinding wheel spindle is carried out in the industrial field, the grinding spindle vibration displacement amplitude decreased from 17.8 to 7.7 before and after balance, fall by as much as 55%, which verifies the validity and feasibility of the system.

Research on Underground Dynamic Fluid Pressure Balance in the Process of Oil Shale In-Situ Fracturing-Nitrogen Injection Exploitation

Oil shale in-situ retorting is a reasonable development technology. However, the ground water may flow into fractures in oil shale layer that impact the process of oil shale in-situ retorting. This paper introduced oil shale in-situ fracturing-nitrogen injection exploitation and a method of dynamic pressure balance between the ground water and high pressure nitrogen to keep the oil shale layer without ground water in the process of oil shale in-situ fracturing-nitrogen injection exploitation. Theoretical basis of dynamic pressure balance between ground water and nitrogen was established through analyzing pressure relationship between ground water and nitrogen in the fractures and field experiment was conducted according to the method. The field experiment results showed that nitrogen pressure maintained high level in the fractures during the stage of building pressure balance of nitrogen and ground water and pushed ground water out of the oil shale layer. Then, nitrogen pressure in the fractures reduced and maintained stable because part of nitrogen in the fractures flowed out from the production well and flow conductivity of fractures enhanced. After the balance between the ground water and high pressure nitrogen was established, water yield of production well reduced more than 85%. It explained that the balance has function of sealing up.

Research on the Field Dynamic Balance Technologies for Large Diesel Engine Crankshaft System

In order to reduce the unbalancing mass and the accompanying unbalancing vibration of diesel engine crankshaft system, the field dynamic balancing method and its key technologies are presented in the paper. In order to separate the unbalancing vibration signal from the total vibration signal of crankshaft system, the fundamental frequency signal fitting principle based on the least square method was introduced firstly, and then wavelet noise reduction method was applied to improve the signal fitting precision of least square method. Based on the unbalancing vibration signal analysis and assessment of crankshaft system, the influence coefficient method was applied to calculate the value and phase of the equivalent unbalancing mass in flywheel. To easily correct the unbalancing condition of crankshaft system, the unbalancing adjustment equipment was designed based on the flywheel structure. The balancing effect of field dynamic balancing system designed for the large diesel engine has been verified by field experiments.

Recent Researches and Patents on Dynamic Balancing Methods and Devices for Rotor System

Background: With the development of high-speed and high-precision rotating machinery, the rotor usually needs to work at very high speeds and the huge unbalancing vibration of rotor may be caused by a tiny unbalancing mass. To reduce the unbalance of rotor, a suitable dynamic balancing method should be designed for different rotor systems. In this article, various patents have been discussed. Objective: The typical dynamic balancing methods and technologies are summarized and analyzed so as to provide some references for dynamic balancing design and application. Method: To make it easier to design the proper balancing measure for actual rotating mechanical system, the dynamic balancing methods for rotor are classified as workpiece dynamic balance, assembling dynamic balance, field dynamic balance and online dynamic balance according to the balancing time of rotor. Results: The principle of all kinds of dynamic balancing method is given firstly, and then advantages, disadvantages and future developments about each balancing method are reviewed in the paper. Conclusion: Corresponding to these balancing methods, the online dynamic balancing method is recommended. Keywords: Device, dynamic balance, method, patent, research, rotor.

A new Method for Dynamic Balancing of Workload and Scalability in Multicore Systems

This paper presents a new method for dynamic balancing of workload and scalability in multicore systems. This method is called LobeNOI (Load balancing engine for NOI - Notification-Oriented Inference). NOI is composed of a set of small and reactive computational entities, which communicate only when needed by avoiding both temporal and structural redundancies. The innovative aspect of the considered approach would be that computational entities carry out inference by means of collaborations based upon direct notifications. This paper actually presents a way to improve the utilization of hardware processing power available in modern computers, more precisely, in multicore systems, through distribution of NOI entities in multiple cores. The main contributions of the method are the transparency in the concurrent software design process and the better hardware utilization. Moreover, NOI presents itself as a promising alternative to compose complex, distributed and scalable applications.

Field Dynamic Balancing for Rigid Rotor-AMB System in a Magnetically Suspended Flywheel

To effectively reject the influence of rotor unbalance on system stability and precision for a magnetically suspended flywheel, this paper proposes a novel rigid rotor field dynamic balancing method based on autocentering control and the equivalence of magnetic control force and the rotor unbalance centrifugal force. By the autocentering control, the rotor is forced to rotate around its geometric axis. After demonstrating the equivalence of the external control force and the rotor unbalance centrifugal force, the rotor unbalance can be identified from the magnetic force. Since the position of the rotor geometric axis can be measured precisely by an eddy current displacement sensor, the high-precision autocentering control can be achieved easily. Furthermore, since the magnetic force is proportional to the control current when the rotor is at its equilibrium point, the magnetic force can be obtained by measuring the control current and multiplying it with the force–current stiffness. Without trial weights, the efficiency of the proposed field dynamic balancing method is high. Finally, the effectiveness and superiority of the proposed rotor balancing strategy have been demonstrated by the experimental results.

CLB: A novel load balancing architecture and algorithm for cloud services

Cloud services are widely used in manufacturing, logistics, digital applications, and document processing. Cloud services must be able to handle tens of thousands of concurrent requests and to enable servers to seamlessly provide the amount of load balancing capacity required to respond to incoming application traffic in addition to allowing users to obtain information quickly and accurately. In the past, researchers have proposed the use of static load balancing or server response times to evaluate load balancing capacity, a lack of which may cause a server to load unevenly. In this study, a dynamic annexed balance method is used to solve this problem. Cloud load balancing (CLB) takes into consideration both server processing power and computer loading, thus making it less likely that a server will be unable to handle excessive computational requirements. Finally, two algorithms in CLB are also addressed with experiments to prove the proposed approach is innovative.

Dynamic Material Balance Study of Gas Reservoir Using Production Data: A Case Study of New Gas Sand of Kailashtila Gas Field

The material balance is one of the fundamental practice in reservoir engineering and is considered as a reliable estimation of hydrocarbons-in-place. A good knowledge of average reservoir pressure is essential to determine original gas-in-place. To have such reservoir pressure, the well needs to be shut-in for few days to months, resulting in loss of production. In the current economic environment, this production loss is often unexpected. In a previous study, Matter and McNeil showed that material balance calculation could be done without shut-in well, which uses flowing well pressure instead of static pressure and constant flow rates. However, a constant production rate for an extended period of time is very challenging production criterion for the majority gas fields. The dynamic material balance is an extension of the flowing material balance that allows either constant or variable flow rate. This study describes the practical application of a method known as Dynamic Material Balance for average reservoir pressure determination using flowing pressures and variable production rates and thus to estimate the original gas-in-place of new gas sand of Kailashtila Gas Field. The main purpose of this study is to apply the method in field cases and to make a comparison with other standard methods of reserve estimation such as volumetric, type curve analysis to see the result and validate the efficiency of its application. These comparisons show a fairly good agreement in gas in place obtained from the dynamic material balance method and that of type curve analysis in this field.

Whole-machine Dynamic Balancing Method without Trial Weights for Multi-span Rotor Shafting Based on Dynamic Finite Element Model

Whole-machine Dynamic Balancing Method without Trial Weights for Multi-span Rotor Shafting Based on Dynamic Finite Element Model

Dynamic Load Balancing of Parallel SURF with Vertical Partitioning

The demand for real-time processing of robust feature detection is one of the major issues in the computer vision field. In order to comply with the requirements, in this paper a parallelization and optimization method to effectively accelerate SURF is proposed. The proposed parallelization method is developed based on a workload analysis of SURF in terms of various aspects, focusing in particular on the load balancing problem. First, the average parallel workload is divided into identical portions using the vertical partitioning method. Then, the load imbalance problem is further resolved using the dynamic partition balancing method. In addition, an optimization method is proposed together with the parallelization method to find and exclude redundant operations in SURF, thus effectively accelerating the feature detection operation when the proposed parallelization method is applied. The proposed method shows a maximum speedup of 19.21 compared to the single threaded performance on a 24-core system, achieving a maximum of 83.80 fps in a real-machine experiment, enabling real-time processing.

Design of Cloud Load Balance Architecture for Web Servers

Cloud services are widely used in manufacturing, logistics, digital applications, and document processing. Cloud services must be able to handle tens of thousands of concurrent requests and to enable servers to seamlessly provide the amount of load balance capacity needed in response to incoming application traffic in addition to allowing users to obtain information quickly and accurately. In the past, scholars proposed using static load balance or server response times to evaluate load balance capacity, both of which cause the server to load unevenly, and in this study, a dynamic annexed balance method is used to solve this problem.

Ash fouling monitoring and key variables analysis for coal fired power plant boiler

Ash deposition on heat transfer surfaces is still a significant problem in coal-fired power plant utility boilers. The effective ways to deal with this problem are accurate on-line monitoring of ash fouling and soot-blowing. In this paper, an online ash fouling monitoring model based on dynamic mass and energy balance method is developed and key variables analysis technique is introduced to study the internal behavior of soot-blowing system. In this process, artificial neural networks (ANN) are used to optimize the boiler soot-blowing model and mean impact values method is utilized to determine a set of key variables. The validity of the models has been illustrated in a real case-study boiler, a 300MW Chinese power station. The results on same real plant data show that both models have good prediction accuracy, while the ANN model II has less input parameters. This work will be the basis of a future development in order to control and optimize the soot-blowing of the coal-fired power plant utility boilers.

On-line monitoring of ash fouling and soot-blowing optimization for convective heat exchanger in coal-fired power plant boiler

This paper presented a comprehensive approach of on-line monitoring and optimization for the soot-blowing system in coal-fired power plant boilers. Due to ash fouling monitoring of heat transfer surfaces of the boiler based on dynamic mass and energy balance method, on-line calculation of boiler thermal efficiency and soft measurements for gas flow rate at the double breezing tail and steam flow rate of reheaters, the performance of boiler's soot-blowing system can be evaluated on-line. And then, the suitable soot-blowing strategies are developed for soot-blowing frequencies and duration optimization. Monitoring results and analysis of an experimental application are given to illustrate the proposed methodologies. The methods proposed in this paper can be applied to state assessment and guidance of soot-blowing operation of boiler's soot-blowing system in order to achieve the purpose of energy conservation, without demanding special instruments or complex computing systems.

Virtual dynamic balancing method without trial weights for multi-rotor series shafting based on finite element model analysis

The traditional influence coefficient dynamic balancing method for multi-rotor series shafting, such as turbine-generator sets, gas turbines, compressor trains, and others, usually needs to startup many times using trial weights along the rotor. Based on finite element model analysis for the multi-rotor series shafting, a virtual dynamic balancing methodology which only needs to collect data of vibration response at operating speed without trial weights is developed in this paper. According to shafting structure and operating parameters, the dynamic finite element model was built by using rotor dynamics theory and finite element simulation technology. The shafting dynamic characteristics and weighted influence coefficient matrix can be gotten by exciting virtual unbalance force on the balance place correspondingly. The effectiveness and flexibility of the proposed method have been illustrated by solving a shafting dynamic balancing example with no trial weights requirements. It is believed that the new methods developed in this work will help in reducing the time and cost of the equipment manufacturer or field dynamic balancing procedures.

Nonlinear dynamics of mechanical systems with friction contacts: Coupled static and dynamic Multi-Harmonic Balance Method and multiple solutions

Real applications in structural mechanics, where the dynamic behavior is linear, are rare. Usually, structures are made of components assembled together by means of joints whose behavior maybe highly nonlinear. Depending on the amount of excitation, joints can dramatically change the dynamic behavior of the whole system, and the modelling of this type of constraint is therefore crucial for a correct prediction of the amount of vibration. The solution of the nonlinear equilibrium equations by means of the Harmonic Balance Method (HBM) is widely accepted as an effective approach to calculate the steady state forced response in the frequency domain, in spite of Direct Time Integration (DTI). The state of the art contact element used to model the friction forces at the joint interfaces is a nodal contact element, where the local contact compliance is modelled by means of linear springs and Coulomb law is used to govern the friction phenomena. In the literature, when the HBM is applied to vibrating systems with joint interfaces and the state-of-the-art contact model is used, an uncoupled approach is mostly employed: the static governing equations are solved in advance to compute the pre-stress effects and then the dynamic governing equations are solved to predict the vibration amplitude of the system. As a result, the HBM steady-state solution may lead to a poor correlation with the DTI solution, where static and dynamic loads are accounted for simultaneously. In this paper, the HBM performances are investigated by comparing the uncoupled approach to a fully coupled static/dynamic approach. In order to highlight the main differences between the two approaches, a lumped parameter system, characterized by a single friction contact, is considered in order to show the different levels of accuracy that the proposed approaches can provide for different configurations.

Double Four-Bar Crank-Slider Mechanism Dynamic Balancing by Meta-Heuristic Algorithms

In this paper, a new method for dynamic balancing of double four-bar crank slider mechanism by meta- heuristic-based optimization algorithms is proposed. For this purpose, a proper objective function which is necessary for balancing of this mechanism and corresponding constraints has been obtained by dynamic modeling of the mechanism. Then PSO, ABC, BGA and HGAPSO algorithms have been applied for minimizing the defined cost function in optimization step. The optimization results have been studied completely by extracting the cost function, fitness, convergence speed and runtime values of applied algorithms. It has been shown that PSO and ABC are more efficient than BGA and HGAPSO in terms of convergence speed and result quality. Also, a laboratory scale experimental doublefour-bar crank-slider mechanism was provided for validating the proposed balancing method practically.

Online bio-inspired trajectory generation of seven-link biped robot based on T–S fuzzy system

This paper proposes a novel method for real-time trajectory generation of a seven-link planar biped robot. Individual joint trajectories are generated by specifying only two key parameters, walking speed and step length. The proposed method combines several methods and concepts including kinematics, dynamics, trajectory generation, experimental design, Takagi–Suguno fuzzy systems, central pattern generator (CPG), ZMP criterion and a dynamic balance method. A fuzzy relationship between walking and CPG parameters is learned using experimental design methodology and T–S fuzzy systems. A method based on the Fourier series is used to tune parameters of the CPG. The proposed method allows making online changes to step length and walking speed while ensuring robot's dynamic balance. A multibody simulation package is selected and the effectiveness of the method is illustrated using several examples. It is also shown that changes in joint angles, as the result of online changes to the walking parameters, occur in a smooth and continuous manner.

Real-time online monitoring of thermal efficiency in coal-fired power plant boiler based on coal heating value identification

This paper presents a comprehensive real-time online calculation model of coal-fired boiler thermal efficiency based on the low heating value identification of the coal. At first, online calculation approach is proposed to overcome the difficulty that the coal qualities into furnace are often changing and not well obtained real-time, by means of the dynamic mass and energy balance method. Secondly, the excess air coefficient and unburned carbon in fly ash which are the important parameters to calculate the boiler thermal efficiency are determined by soft measurement methods. The paper illustrates the effectiveness of the models as well as the validation of the online simulation, starting from real operation data. The outcome is that it is possible to significantly satisfy the accuracy of online identification of the low heating value (LHV) of the coal into the boiler, and the real-time of online calculations provided by indirect heat balance method. The models can be used to the real-time control and optimisation of the coal-fired utility boilers.

Dynamic balancing method for the single-threaded, fixed-pitch screw rotor

The screw rotor is the most important component of dry screw vacuum pumps used in various industrial applications. In this paper, a method for determining the dynamic balance of the single-threaded, fixed-pitch screw rotor is proposed based on previous research. A specific structure is designed in order to meet the demand of engineering. In this structure, two cavities with identical sections are preformed on both end faces of the rotor. The two cavities have the same shape, the same symmetric location relative to each other, and the same pitch with the screw rotor. All the structural parameters of the cavities are described, and the dynamic balancing of the screw rotor is feasible by closely following the procedure. Considering the calculation method does not depend on the form of the end-face profile, it can be used with any type of screw rotor end-face profile.

Mathematical Model and Method of Dynamic Balance for Two Kinds of Screw Rotors

Mathematical Model and Method of Dynamic Balance for Two Kinds of Screw Rotors