Study on Quality Decisions in Supply Chain considering the Lagged Time and Retailers Competition

The lagged time on goodwill is a common phenomenon in the process of quality improvement, which plays an important role in making quality strategy of supply chain. With increasing public attention to quality, supply chain quality management has become a research focus in recent years. This paper probes into the lagged time of quality on goodwill under the competitive environment of retailers and constructs a lagged differential equation of quality on goodwill based on the Nerlove–Arrow model. The results indicate that the optimal goodwill and quality are higher under centralized decision-making than under decentralized decision-making; however, whether or not the profit of the entire supply chain is higher under centralized decision-making depends on the span of the lagged time. Under decentralized decision-making, the lagged time of product quality on goodwill is favorable to retailers but unfavorable to manufacturers and vice versa. Therefore, when competition is low, a supply chain tends to adopt centralized decision-making. When competition is intense, it is appropriate for a supply chain to adopt decentralized decision-making. In conclusion, this paper analyzes the effects of the lagged time on the optimal quality level and supply chain profit as well as the effect of the competition coefficient on research findings concerning supply chain profit under centralized and decentralized decision-making to verify the relevant conclusions of this paper.

Stability Analysis of Competition among Companies: A Guide from Predator Prey Modeling

This paper studied the behavior of two companies using predator prey model as the basis. As the companies are competing constantly, it affects them because their interaction determines the availability of resources for their growth. Considering growth of these companies, the parameters which were respectively the carrying capacity and competitive impact of either of the competing companies on each other were included in the model. Equilibrium point and their existence criteria were analyzed to find the threshold that will guarantee the coexistence of both companies or collapse of either of them or both. It was shown that both companies can grow and rise simultaneously, (coexist) by dividing their resources correspondingly or that even the slightest change in their competition coefficient can lead to adverse situation, which may cause complete disappearance of one of the companies or both. We conclude that as long as these companies did not operate beyond their effective carrying capacity and equally maintain their respective competitive advantage, coexistence might be achieved. Some simulations are also given to illustrate our results.

The Port Service Ecosystem Research Based on the Lotka-Volterra Model

Under the new normal of China’s economy, the competition among the port enterprises is not only the competition of the core competence of the port, the port industry chain or the port supply chain, but also the competition of the port service ecosystem. In this paper, the concept and characteristics of the port service ecosystem is discussed, a hierarchical model of the port service ecosystem is constructed. As an extended logistic model, Lotka-Volterra model is applied to study the competitive co-evolution and mutually beneficial co-evolution of enterprises in the port service ecosystem. This paper simulates the co-evolution of enterprises in the port service ecosystem by using MATLAB programming. The simulation results show that the breadth of the niche of the enterprises is changing with the change of the competition coefficient and the coefficient of mutual benefit in the port service ecosystem. Based on that, some proposals are put forward to ensure the healthy and orderly development of the port service ecosystem.

LOTKA–VOLTERRA TWO-SPECIES SYSTEM WITH PERIODIC INTERRUPTION OF COMPETITION

We consider the two-species Lotka–Volterra competition system with a temporally periodic interruption of competition coefficient. We assume that the competition coefficient is constant in a time interval of fixed length τ+, while it is zero in the other time interval of length τ-. The temporal variation of the competition coefficient is rigorously periodic with period τ+ + τ-, in which the competition coefficient becomes a given positive constant and zero by turns, the other parameters being constant in time. We analyze the system analytically and numerically, and derive the condition for the permanence of the whole system, the coexistence of two competing species, and the change of the species-dominance in terms of the competition. We discuss some interesting natures of our system, distinguished from the original two-species Lotka–Volterra competition system with constant competition coefficients. The temporal interruption of competition could cause the change of the destiny of competing species.

Estimation of Crop Yield Loss Due to Interference by Multiple Weed Species

Previous efforts to model crop yield loss from multiple weed species constructed competitive indices based on yield loss from individual weed species. Our model uses a multispecies modification of Cousens’ rectangular hyperbolic yield function to estimate a nonlinear competitive index for weed-crop interference. Results from 13 Minnesota and Wisconsin data sets provide measures of the relative competitiveness of mixed green and yellow foxtails, common lambsquarters, redroot pigweed, velvetleaf, and several other weed species. Competition coefficient estimates are stable over years, but not locations.

Adjustment for competition between varieties in plant breeding trials

SUMMARYA method is proposed for correcting for competition effects in yield trials by joint regression of plot yields on to the yields of neighbours. Estimation of the variety effects and competition coefficient along with tests of significance are described for a sugar-beet trial with single-row plots where competition effects are assumed to extend only to plants in immediately adjacent rows. For designs which are balanced for neighbouring varieties it is feasible to estimate separate varietal competition coefficients which may be partitioned into components for sensitivity and aggressiveness. An example is given of this extended model fitted to a competition diallel of seven species. While species differed in their sensitivity to competition there was no essential difference between inter- and intra-species behaviour. The model is used to assess comparative varietal performance in monocultures from performance in small plot trials.(Note that the general term ‘variety’ is used throughout this paper to refer to progenies at any stage in a selection programme.)