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This paper discusses the electromagnetic unbalances of transmission lines caused by mutual impedances. The unbalance factors of 27 different transmission line configurations have been studied by using a digital computer. The impacts of transposition, phase arrangement, additions of transformer, and capacitors to the lines in terms of circulating currents, sequence impedances, and net through and circulatory unbalance factors have been investigated extensively. Furthermore, the impact of “n” overhead ground wires on the electromagnetic unbalance factors of untransposed single‐ and double‐circuit transmission lines have been studied and the results have been tabulated and plotted.

One of the major problems faced by industry is vibrations in rotating parts. Vibration is a to-and-fro movement of rotating mechanical parts and has many detrimental effects on machinery. It is obvious that no movement can be achieved without consumption of energy. All the energy consumed in vibration of mechanical parts is useless. Unbalance is one of the most common reasons for vibrations. This paper aims to experimentally evaluate the effect of unbalance in a shaft–rotor system on power consumption. An experimental setup consisting of a shaft and a rotor mounted on antifriction bearing was built-up. The shaft was driven through a flexible coupling, by a variable speed DC motor. The shaft–rotor system was rotated at different speeds and electrical power consumed by the system was measured at specific speeds varying from 1,200 to 2400 rpm. The rotor was balanced to grade G6.3 at 1,200 rpm. The power consumption by shaft in balanced condition was taken as baseline data for the further work. The rotor was then made unbalanced by adding different masses at 60 mm radius, and power consumption was recorded again at the same speeds. It was observed that average power loss due to unbalance is of 0.11watt/gm.mm unbalance. This can amount to 2.75 kw if there is unbalance of 50 gm at a radius of 500 mm. This work is meant to emphasis on the fact that the power consumption can be reduced if the vibrations can be kept under control.

The experimental setup consisting of a rotor–shaft system was fabricated. The shaft was supported on two anti-friction bearings. The shaft is driven by a 0.25 HP DC motor. The speed of the motor can be varied by a speed controlling device. A digital ammeter and voltmeter are connected to measure the input current and voltage to the system. The rotor was rotated at different speeds after two-plane balancing and the parameters like voltage, current drawn, rms velocity (average of drive and non-drive side bearing) and displacement at 1× frequency were recorded. The base line data for the balanced shaft–rotor system were recorded for further use.

Power consumption increases with increase in unbalance at each of the speeds. Total power consumed at resonant frequency is high. The average power consumed “W/gm.mm” increases at higher speed due to increased damping force of lubricant in bearings combined with the effect of resonance. Average power consumed due to unbalance is about 0.11 W/gm.mm unbalance. It is important to reduce the vibration to save power which can be effectively achieved by balancing the rotating parts in the machinery.

The experimentation is done on a small rotor. When the same work is done on real situations where the rotors are heavy, we may expect some differences in the actual effect of unbalance on the power consumption.

The experimental work have a huge application in industry in condition monitoring. The power may tend to increase not only because of the unbalance but also due to other reasons of vibrations like misalignment, loose foundation, poor bearing conditions, etc. The power loss may increase due to any other reasons mentioned above. The degree of power saving due to steps taken for reducing vibration will depend on the existing vibration levels.

The work highlights the effect of power loss due to vibrations. Even (1 per cent) small amount of power saved can save millions of dollars in industry, as there are many rotating parts which run 24 × 7. The emphasis is on condition-based monitoring which will help in power saving beyond the conventional advantages of condition monitoring.

The experimentation clearly quantifies power loss in absolute form that is the power loss is expressed per gm.mm of unbalance and not as the percentage of electrical or mechanical power, input or output. The percentage values may be misleading some times, as SMALL percentage of large values is also LARGE and hence should be taken into consideration.

Unbalanced bidding can seriously imposed the government from obtaining the best value for the taxpayers' money in public procurement since it increases the owner's cost and decreases the fairness of the competitive bidding process. How to detect an unbalanced bid is a challenging task faced by theoretical researchers and practical actors. This study aims to develop an identification method of unbalanced bidding in the construction industry.

The identification of unbalanced bidding is considered as a multi-criteria decision-making (MCDM) problem. A data-driven unit price database from the historical bidding document is built to present the reference unit prices as benchmarks. According to the proposed extended TOPSIS method, the data-driven unit price is chosen as the positive ideal solution, and the unit price that has the furthest absolute distance measure as the negative ideal solution. The concept of relative distance is introduced to measure the distances between positive and negative ideal solutions and each bidding unit price. The unbalanced bidding degree is ranked by means of relative distance.

The proposed model can be used for the quantitative evaluation of unbalanced bidding from a decision-making perspective. The identification process is developed according to the decision-making process. The finding shows that the model will support owners to efficiently and effectively identify unbalanced bidding in the bid evaluation stage.

The data-driven reference unit prices improve the accuracy of the benchmark to evaluate the unbalanced bidding. The extended TOPSIS model is applied to identify unbalanced bidding; the owners can undertake objective decision-making to identify and prevent unbalanced bidding at the stage of procurement.

This paper aims to provide a precision assembly method to improve the aircraft engine quality of initial unbalance with the purpose of founding the process for mass eccentricity propagation and demonstration of assembly process. The proposed method can be used for assembly guidance, tolerance allocation and so on, especially for the assembly with a large number of rotors and the assembly requirements of initial unbalance and coaxiality in high precision.

This paper proposes a constrained optimization-build method to minimize initial unbalance of aircraft engine assembly, which takes amount of unbalance and concentricity of each rotor into account. A constrained nonlinear programming model is extracted by choosing the initial unbalance as the objective function, and choosing the coaxiality and assembly orientations as the nonlinear constraints. The initial unbalance is reduced stage-by-stage by controlling the assembly angle of each rotor.

The validity and accuracy of the proposed method is verified by the multistage rotors assembly through experiments run with the measuring instruments. Compared with the direct-build method, the initial unbalance of final assembly using proposed method is reduced by 22.2% in four rotors assembly.

Different from the geometric eccentricity propagation control methods to reduce the initial unbalance indirectly, this paper establishes mass eccentric propagation model in multistage rotors assembly of aircraft engine for the first time. It provides a new idea to establish the relationship between the amount of unbalance of each rotor and the initial unbalance of multistage rotors.

The purpose of this study is to investigate the effect of roller dynamic unbalance on cage stress.

Considering the impact of roller dynamic unbalance, the dynamic analysis model of high-speed cylindrical roller bearing is established. And then the results of dynamic model are used as the boundary conditions for the finite element analysis model of roller and cage to obtain the cage stress.

Roller dynamic unbalance affects the contact status between roller and cage pocket and causes the overall increase in cage stress. The most significant impact on cage stress is roller dynamic unbalance in angular direction of roller axis, followed by radial and axial directions. Smaller radial clearance of bearing and a reasonable range of pocket clearance are beneficial to reduce the impact of roller dynamic unbalance on cage stress; the larger cage guide clearance is a disadvantage to decrease cage stress. The impact of roller dynamic unbalance on cage stress under high-speed condition is greater than that in low-speed conditions.

The research can provide some theoretical guidance for the design and manufacture of bearing in high-speed cylindrical roller bearing.

The purpose of this paper is to study the influence of the cage dynamic unbalance on the dynamic performances in cylindrical roller bearings.

The dynamic analysis model which considering cage dynamic unbalance is presented, and the relationship between the cage dynamic unbalance and the cage stability, the cage slip ratio and the cage skew angle is investigated.

Cage dynamic unbalance has a great effect on the cage stability. The cage dynamic unbalance which in an axial excursion affects the cage characteristics is greater than that only in the radial direction. The cage slip ratio and the cage skew increases with the cage dynamic unbalance, especially with the axial excursion. The non-metal cage is more sensitive to the cage dynamic unbalance than that of the metal cage.

The analytical method and model can be applied by the bearing engineering designers.

To achieve sustainability for a construction project requires the achievement of economic, environmental and social sustainability at the same time. The economic sustainability of a project should be built into the stipulated cost. The unbalanced bidding always contribute cost overrun for a construction project. The purpose of this paper is to develop a method for identifying unbalanced bidding.

The problem of identifying unbalanced bidding is a comprehensive evaluation problem. All line items and bidders in bills of quantities are evaluation factors and evaluation objects, respectively, and the engineer’s estimated prices are considered as the evaluation benchmarks. The weights of these factors are determined through integrating the entropy weight method and the analytic hierarchy model, which consider subjective and objective factors in the weighting process.

The proposed model can be used to quantitatively evaluate unbalanced bids. The identification process can be analyzed within a short period, specifically with the aid of Microsoft Excel, reducing delays in awarding contracts. The results show that the model will support owners as they efficiently and effectively identify unbalanced bids in the bid evaluation stage to mitigate the negative consequences of unbalanced bidding.

A case study is given to verify the feasibility and practicability of the proposed method, which not only assists owners in efficiently and effectively identifying unbalanced bidding, but also promotes the economic sustainability of construction projects.

The fuzzy comprehensive evaluation method is used to detect unbalanced bidding, allowing owners to be objective as they identify and reduce unbalanced bidding at the procurement stage.

This paper aims to evaluate the effect of optimal use of rooftop photovoltaic (PV) systems on improving the loss of life (LOL) of distribution transformers, reducing power losses as well as the unbalance rate of the 69-bus distribution network.

The problem is studied in three scenarios, considering different objective functions as multi-objective optimization in balanced and unbalanced operations. Meta-heuristic golden ratio optimization method (GROM) is used to determine the optimal size of the rooftop PV in the network.

The simulation results show that in all scenarios, the GROM by optimally installing the rooftop PV is significantly capable to reduce the transformer distribution loss of loss, unbalance rate and power loss as well as reduce the temperature of the oil and transformer winding. Also, the lowest %LOL, power loss and unbalance rate occurred in the second scenario for the balanced network and first scenario, respectively. In addition, the results showed that the unbalance of the network results in increased power losses and LOL of the distribution transformer.

The better capability of GROM is proved compared with the grey wolf optimization algorithm with better objective function and by achieving better values of LOL, unbalance rate and power loss. The results also showed that the %LOL, unbalance and power losses are weakened compared to without considering the PV cost but the achieved results are realistic and cost-effective.

The necessity for refinement of airscrew balance in order to eliminate destructive vibration from this source is due largely to the continuously improving standards of passenger comfort of modern aeroplanes and to the operator's desire to extend the normal service life of the power plant and its accessories as well as that of the aeroplane structure. Power plant vibration already has been reduced to a degree where, in standard aeroplanes, there is no longer danger of major structural failure due to vibration originating from this source. Efforts to refine further the balance of engines and airscrews are directed mainly at increasing passenger comfort and extending the service life of aeroplane equipment.

THE balancing of rotating parts can be effected either on a balancing machine, or by means of vibration measurements carried out on the completed assembly.