Zhenpeng He, Wenqin Gong, Weisong Xie, Guichang Zhang and Zhenyu Hong
Piston ring dynamic problem plays an important role in the lubricant characteristics of a reciprocating engine, which lead to engine wear and the increased consumption of…
Abstract
Purpose
Piston ring dynamic problem plays an important role in the lubricant characteristics of a reciprocating engine, which lead to engine wear and the increased consumption of lubricating oil. A cavitation analysis of the piston ring lubrication with two-dimensional Reynolds equation has rarely been reported owing to the complex working condition. The purpose of this study is to establish a precise model that can provide guidance for the design of the piston ring.
Design/methodology/approach
In this paper, a cavitation model and its effect on the piston ring lubrication was studied in a simulation program based on the mass-conserving theory which is solved by means of the Newton–Raphson method. In this study, some models such as mixed lubrication, asperity contact, blow-by/blow-back flow and cavitation have been coupled with the lubrication model.
Findings
The established model has been compared with the traditional model that deals with cavitation by using the Reynolds boundary condition algorithm. The cavitation zone, pressure distribution and density distribution between the piston ring and the cylinder have also been predicted. Studies of the changing trend for the pressure distribution and the cavitation zone at few typical crank angles have been listed to illustrate the cavitation changing rule. The analysis of the results indicates that the developed simulation model can adequately illustrate the lubrication problem of the piston ring system. All the analyses will provide guidance for the oil film rupture and the reformation process.
Originality/value
A two-dimensional cavitation model based on the mass-conserving theory has been built. The cavitation-forming and -developing process for the piston ring–liner lubrication has been studied. Non-cavitation occurs in the vicinity of top dead center and bottom dead center. The non-cavitation period will be longer in the vicinity of 360° of crank angle. The density distribution in the cavitation zone can be obtained.
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Corporate risk management is one of the critical concerns of managers when they make investment allocation decisions among multiple projects. The purpose of this paper is to…
Abstract
Purpose
Corporate risk management is one of the critical concerns of managers when they make investment allocation decisions among multiple projects. The purpose of this paper is to address corporate investment issues illustrated by target‐beating in capital budgeting, and further discuss their applications in financial management, especially in venture capital finance.
Design/methodology/approach
Value‐at‐risk, a typical down‐side risk measure which is considered more appropriate for economic agents, is applied to the analysis. Probability theory and optimal control methodologies are used to derive analytical solutions.
Findings
By maximizing the probability of beating a pre‐determined target, an analytical optimal corporate investment allocation strategy is presented, and the corresponding probability and expected earliest time of success derived.
Research limitations/implications
Various types of utility functions of economic agents and other dynamic downside risk measures can be considered in future research along this line.
Practical implications
This paper paves the road for applications of continuous‐time downside risk in making corporate investment decisions, especially in the field of new venture finance.
Originality/value
As one of the early studies investigating optimal investment decisions in continuous‐time downside risk‐based capital budgeting system, this project sheds light on corporate risk management, and provides risk‐averse decision makers with an effective tool.
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One of the agency conflicts between investors and managers in fund management is reflected by risk‐taking behaviors led by their different goals. The investors may stop their…
Abstract
Purpose
One of the agency conflicts between investors and managers in fund management is reflected by risk‐taking behaviors led by their different goals. The investors may stop their investments in risky assets before the end of the investment horizon to minimize risk, while the managers may do so to entrench their reputation so as to pursue better opportunities in the labor market. This study aims to consider a one principal‐one agent model to investigate this agency conflict.
Design/methodology/approach
The paper derives optimal asset allocation strategies for both parties by extending the traditional dynamic mean‐variance model and considering possibilities of optimal early stopping. Doing so illustrates the principal‐agent conflict regarding risk‐taking behaviors and managerial investment myopia in fund management.
Practical implications
This paper not only paves the way for further studies along this line, but also presents results useful for practitioners in the money management industry.
Findings
According to the theoretical analysis and numerical simulations, the paper shows that potential early stop can make the agency conflict worsen, and it proposes a way to mitigate this agency problem.
Originality/value
As one of the exploratory studies in investigating agency conflict regarding risk‐taking behaviors in the literature, this study makes multiple contributions to the literature on fund management, asset allocation, portfolio optimization, and risk management.
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Lingwen wei, Yan Hong and Xianyi Zeng
The purpose of this research is to conduct a theoretical prediction study exploring the effectiveness of different content marketing strategies in expanding the second-hand market…
Abstract
Purpose
The purpose of this research is to conduct a theoretical prediction study exploring the effectiveness of different content marketing strategies in expanding the second-hand market for fashion brands, comparing the costs and risks involved in these strategies in practice.
Design/methodology/approach
First, the expert interview method is employed to extract the content marketing strategies of the fashion second-hand market. Then, a descriptive space that is able to identify various fashion brand images is established. Then, experts' perceptions of the relationships between content marketing strategies and fashion brand image dimensions are obtained through a subjective evaluation procedure. Data of semantic evaluation were quantified and analyzed using the fuzzy logic method.
Findings
When fashion brands expand to the second-hand market, they not only need to focus on improving the individual differentiation of products but also give priority to the quality of products and services and the overall customer experience. Exploring the “social impact strategy” will become an important direction for the development of fashion brands in the future.
Originality/value
The research methodology employed herein exhibits a noteworthy degree of novelty. This study introduces a pioneering theoretical prediction approach utilizing fuzzy logic, marking the inaugural exploration of this emerging and captivating dimension within the context of the study. Simultaneously, the study provides comparative results among content marketing strategies for expanding the fashion second-hand market, offering guidance for market expansion.
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Xun Li, Hwee Huat Tan, Craig Wilson and Zhenyu Wu
Exit strategies are critical for external private equity holders, such as venture capitalists and business angels, to receive investment returns successfully. The paper models the…
Abstract
Purpose
Exit strategies are critical for external private equity holders, such as venture capitalists and business angels, to receive investment returns successfully. The paper models the exit decision as a fixed date with the option to exit early, and develop an approach to help private equity holders determine an optimal early exit region based on a target equity value and the time remaining.
Design/methodology/approach
The paper sets up a continuous time model to derive analytical solutions and apply simulations to numerical examples in this study.
Findings
By numerically analyzing the nature of the solution the paper illustrates that a higher return drift of the investee company, a lower return volatility of the investee company, and a higher target return of the private equity holder results a smaller early exit region.
Originality/value
This study helps determine the optimal time of stopping investments, and provides venture capitalists with a usable way to make exit decisions.
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Zhenyu Li, Bin Wang, Haitao Yang and Hong Liu
Rapid satellite capture by a free-floating space robot is a challenge problem because of no-fixed base and time-delay issues. This paper aims to present a modified target…
Abstract
Purpose
Rapid satellite capture by a free-floating space robot is a challenge problem because of no-fixed base and time-delay issues. This paper aims to present a modified target capturing control scheme for improving the control performance.
Design/methodology/approach
For handling such control problem including time delay, the modified scheme is achieved by adding a delay calibration algorithm into the visual servoing loop. To identify end-effector motions in real time, a motion predictor is developed by partly linearizing the space robot kinematics equation. By this approach, only ground-fixed robot kinematics are involved in the predicting computation excluding the complex space robot kinematics calculations. With the newly developed predictor, a delay compensator is designed to take error control into account. For determining the compensation parameters, the asymptotic stability condition of the proposed compensation algorithm is also presented.
Findings
The proposed method is conducted by a credible three-dimensional ground experimental system, and the experimental results illustrate the effectiveness of the proposed method.
Practical implications
Because the delayed camera signals are compensated with only ground-fixed robot kinematics, this proposed satellite capturing scheme is particularly suitable for commercial on-orbit services with cheaper on-board computers.
Originality/value
This paper is original as an attempt trying to compensate the time delay by taking both space robot motion predictions and compensation error control into consideration and is valuable for rapid and accurate satellite capture tasks.
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Yue Yu, Cong Zhang, Zhenyu Chen and Zhengdi Zhang
This paper aims to investigate the singular Hopf bifurcation and mixed mode oscillations (MMOs) in the perturbed Bonhoeffer-van der Pol (BVP) circuit. There is a singular periodic…
Abstract
Purpose
This paper aims to investigate the singular Hopf bifurcation and mixed mode oscillations (MMOs) in the perturbed Bonhoeffer-van der Pol (BVP) circuit. There is a singular periodic orbit constructed by the switching between the stable focus and large amplitude relaxation cycles. Using a generalized fast/slow analysis, the authors show the generation mechanism of two distinct kinds of MMOs.
Design/methodology/approach
The parametric modulation can be used to generate complicated dynamics. The BVP circuit is constructed as an example for second-order differential equation with periodic perturbation. Then the authors draw the bifurcation parameter diagram in terms of a containing two attractive regions, i.e. the stable relaxation cycle and the stable focus. The transition mechanism and characteristic features are investigated intensively by one-fast/two-slow analysis combined with bifurcation theory.
Findings
Periodic perturbation can suppress nonlinear circuit dynamic to a singular periodic orbit. The combination of these small oscillations with the large amplitude oscillations that occur due to canard cycles yields such MMOs. The results connect the theory of the singular Hopf bifurcation enabling easier calculations of where the oscillations occur.
Originality/value
By treating the perturbation as the second slow variable, the authors obtain that the MMOs are due to the canards in a supercritical case or in a subcritical case. This study can reveal the transition mechanism for multi-time scale characteristics in perturbed circuit. The information gained from such results can be extended to periodically perturbed circuits.
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The purpose of this paper is to examine the relationship between IPO lockups and founder-CEOs’ compensation and incentives in newly public firms. The paper argues that existence…
Abstract
Purpose
The purpose of this paper is to examine the relationship between IPO lockups and founder-CEOs’ compensation and incentives in newly public firms. The paper argues that existence and length of lockup agreements are affected by bargaining power of founders, which will consequently influence the determination of their compensation contracts.
Design/methodology/approach
Multivariate tests are constructed to examine the relationship between IPO lockups and executive compensation. OLS, fixed-effect panel data model, and the Heckman two-stage model are all utilized to conduct the tests.
Findings
The study finds that lockup existence and lockup length are negatively related to founder-CEOs’ total compensation and positively related to founder-CEOs’ equity incentives. The results hold after controlling for the endogenous decision to sign a lockup agreement at the IPO.
Research limitation/implications
The paper's results suggest that the power of founders and other insiders is a crucial factor in the lockup determination process besides economic factors identified in previous studies. The paper's results also echo the political power theory in the management literature which suggests that an organization's decision making is heavily influenced by relative power of organizational members and reflects their preference.
Originality/value
The paper raises a new explanation for the determinant of IPO lockups that supplements the extant theories. The paper argues that existence and length of lockup agreements could be affected by bargaining power of insiders.
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Gaoyuan Qin, Fengming Tao, Lixia Li and Zhenyu Chen
In order to reduce logistics transportation costs and respond to low-carbon economy, the purpose of this paper is to study the more practical and common simultaneous pickup and…
Abstract
Purpose
In order to reduce logistics transportation costs and respond to low-carbon economy, the purpose of this paper is to study the more practical and common simultaneous pickup and delivery vehicle routing problem, which considers the carbon tax policy. A low-carbon simultaneous pickup and delivery vehicle routing problem model is constructed with the minimum total costs as the objective function.
Design/methodology/approach
This study develops a mathematical optimization model with the minimum total costs, including the carbon emissions costs as the objective function. An adaptive genetic hill-climbing algorithm is designed to solve the model.
Findings
First, the effectiveness of the algorithm is verified by numerical experiments. Second, the research results prove that carbon tax mechanism can effectively reduce carbon emissions within effective carbon tax interval. Finally, the research results also show that, under the carbon tax mechanism, the effect of vehicle speed on total costs will become more obvious with the increase of carbon tax.
Research limitations/implications
This paper only considers the weight of the cargo, but it does not consider the volume of the cargo.
Originality/value
Few studies focus on environmental issues in the simultaneous pickup and delivery problem. Thus, this paper constructs a green path optimization model, combining the carbon tax mechanism for the problem. This paper further analyzes the impact of carbon tax value on total costs and carbon emission; at the same time, the effect of vehicle speed on total cost is also analyzed.