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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.

WHEN an airscrew leaves the factory, where it has been brought within close limits of perfect force, moment, and aerodynamic balance, the problem of maintaining it in smooth operation throughout its life is only partly solved. The precision of balance which should be met for optimum performance is higher than any piece of mechanism can preserve indefinitely even though it be judged perfect by ordinary standards. Surface abrasion of the blades, material lost in smoothing and polishing, changes in bearing clearance, even though insignificant from the standpoint of mechanical operation; these as well as wear on the centring surfaces of the airscrew shaft and cones may easily conspire to produce unbalance readily detectable in the aeroplane cabin.

In the inelastic stability analysis of plated structures, incremental‐iterative finite element methods sometimes encounter prohibitive solution difficulties in the vicinity of sharp limit points, branch points and other regions of abrupt non‐linearity. Presents an analysis system that attempts to trace the non‐linear response associated with these types of problems at minor computational cost. Proposes a semi‐heuristic method for automatic load incrementation, termed the adaptive arc‐length procedure. This procedure is capable of detecting abrupt non‐linearities and reducing the increment size prior to encountering iterative convergence difficulties. The adaptive arc‐length method is also capable of increasing the increment size rapidly in regions of near linear response. This strategy, combined with consistent linearization to obtain the updated tangent stiffness matrix in all iterative steps, and with the use of a “minimum residual displacement” constraint on the iterations, is found to be effective in avoiding solution difficulties in many types of severe non‐linear problems. However, additional procedures are necessary to negotiate branch points within the solution path, as well as to ameliorate convergence difficulties in certain situations. Presents a special algorithm, termed the bifurcation processor, which is effective for solving many of these types of problems. Discusses several example solutions to illustrate the performance of the resulting analysis system.

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 purpose of this paper is to propose a method to remit or mitigate deterioration resulting from the influence of short data length to existing signal extracting methods.

Careful design of the pre-filtering circuits to refrain most of the noise and disturbance and remove the influence of operation speed of the concerned balancing machine. Based on the analysis on the spectral feature of the unbalance vibration signal, a pre-filtering circuit is designed, then the signal extension method based on AR prediction model are discussed and used to prolong sampled signal.

With the extension method, sampled signal can be extended to required length to enhance the performance of refraining nearby frequency disturbance. The results of simulation and field experiments demonstrate the feasibility of the presented extension method.

Improved measurement efficiency of balancing machine and provided a method to trade off between measurement accuracy and measurement efficiency.

The paper presents a way to improve extraction accuracy and frequency resolution with limited cycles of unbalance vibration signal.

The design of jet engine parts makes particular claims on the balancing machines used: shortest spinning time in the balancing machine, e.g. no nulling and calibration runs—set up of the plane computer at stand still—exact plane setting even at close compensation plane distances and large bearing plane space—installation of rotors with their own operational ball or roller bearings without necessity of the parasitic mass of connection frames or squares.

This paper aims to present a model that explains how knowledge contributions of international joint venture (“IJV”) partners can be balanced or imbalanced, which affects each partners’ trust needs, with implications for future partner relationships.

Illustrative examples aid in explaining propositions associated with the knowledge/trust needs balance model. In addition, consideration is given to the trust-building complication of liability of foreignness and the implications balance or imbalance.

In total, 12 illustrative cases are evaluated to determine whether the knowledge contributions of the IJV partners are balanced. Knowledge intensity associated with the venture is assessed to determine the value of the foreign firm partner’s knowledge contribution. Cultural distance between the relevant countries provides a measure of the host country partner’s knowledge contribution. Balance is assessed after factoring in mitigating partner experience. The cases provide examples of four different balance/imbalance situations.

A critical aspect of a successful IJV is knowledge sharing and trust is required for the freest flow of information. It is important for firms entering into IJVs to more fully understand the relationship between the knowledge contributions of IJV partners and trust. When knowledge contributions are more evenly balanced, the relationship between the partners will be stronger.

The paper distinguishes between balance and stability/instability, expands the literature on knowledge intensity and contributes the new concept of trust needs. Balance at the start of an IJV has implications for the future relationship of the partners.

The flying capacitor converter (FFC) balances the clamping capacitor voltages naturally when phase shifted carrier modulation is used. Several models that describe this mechanism, and to estimate the time constants following a perturbation, are discussed in the literature. However, due to the model complexity, numerical methods must be used to evaluate these models. This paper aims to present a closed form expression, using a reference table, that describes a maximum bound for the voltage balancing time constant.

The FCC is analysed in the frequency domain. A decomposition of the characteristic matrix that describes the voltage balancing mechanism is used. The resulting real symmetric matrix is factorised by using approximations of the load characteristics at the frequencies of interest.

The minimum eigenvalue of the factorised matrix is used to determine a maximum bound for the time constant of the voltage balancing. Since the factorised matrix is independent of variations in switching frequency and load, the eigenvalue of interest can be calculated once and tabulated.

The closed form expression can be used for quick calculations of the maximum time constant under different operating conditions. Furthermore, the expression provides considerable insight into the influences circuit design choices have on the balancing mechanism.

In Bangladesh, the chemical industry is one of the expanding industries based on current statistical data analysis. Green supply chain management (GSCM) is pivotal in order to compete with the global competition. This paper main aim is to discuss a systematic approach to build a structural outline. The purpose of the proposed structural outline is to predict the constructive implementation of GSCM especially on chemical industry in Bangladesh.

This proposed structural framework evaluates the suitable interrelationship next to the barriers of GSCM in the Bangladesh's chemical industry. Here, on the basis of literature review and survey from expert opinions by the use of the Delphi methodology in total eight barriers were concluded. Here additionally, MICMAC analyses were applied to determine the driving and dependence power. Furthermore, the frameworks outline for the barriers were included by means of total interpretive structural modeling (TISM) method.

Based on the analysis, the most significant barriers were found lack of supporting laws and guidance from the government and cost of disposal of hazardous products.

The TISM technique only has implemented to develop the framework, whereas other tools or structural equation modeling (SEM) technique can be used to develop and validate the frameworks for barriers.

In this research, Delphi method questionnaire generated based on the GSCM in the Bangladesh chemical sector. This study will assist the industrial managers to assess and evaluate the crucial sectors, whereas they should give priority to apply the GSCM in the Bangladesh chemical industry.

This study investigates whether the disclosure of derivatives is value relevant in emerging markets and evaluates the effects of the 2008/2009 global financial crisis on the value relevance of derivative disclosures.

Panel regression models using sub-samples and a crisis interaction term were applied to a sample of the 200 largest non-financial firms by market capitalization listed on the Johannesburg Stock Exchange (JSE) from 2005 to 2017 to assess the consequences of the financial crisis.

The results suggest that the disclosure of derivatives is value relevant in the hitherto understudied context of emerging markets. The 2008/2009 financial crisis had a significant impact on derivatives use and the value relevance of derivatives disclosure by JSE-listed companies.

Companies should reconsider both how they employ derivatives as part of their risk management practices and how they communicate derivatives use to stakeholders in the financial statements. The findings facilitate a comparative analysis across various market contexts by researchers and assist investors in better decision-making. The findings can influence regulatory practices and can help standard setters to review disclosure requirements.

The benefits of corporate hedging were studied from an emerging market perspective, using an original dataset and approach to investigate the effects of international financial volatility on emerging markets. The authors tested whether companies are valued differently, based on their disclosure of the use of derivatives in the financial statements, and the effect of the financial crisis on the value relevance derivatives disclosures.