Browsing by Author "Yan, Jun"
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- ItemOpen AccessThe effect of trade unions on the inequality of wage earnings in South Africa(2002) Yan, Jun; Leibbrandt, MurrayThe paper begins with an introduction of trade unions in South Africa, focusing on the union membership trend in the last two decades of the twentieth century. This is followed by a review of work on earnings functions and modelling South African trade unions in chapter 2. The aim of this chapter is to show what work has been done in the area of earnings functions and trade unions. It also highlights the contribution of this paper as analysing the role of trade unions in determining earnings inequality and not just earnings levels. Chapter 3 analyses the variables in a trade union model, such as education, location, gender, experience, sector and occupation. Chapter 4 examines the decomposition of the effect of trade unions on the inequality of wage earnings. We find that the result of effect of trade unions on earnings inequality is higher than in comparable international work. The effect is much higher in the general earnings equation with union interactive variables than the equation with a single union dummy. We also find that, for the overall contribution to earnings inequality, education, sector and location have higher contributions in the non-unionised group than the unionised group. This indicates that trade unions have significant effect in dampening the effect of other variables on earnings inequality.
- ItemOpen AccessInvestigation of the impact of demand elasticity and system constraints on electricity market using extended Cournot approach(2015) Yan, Jun; Folly, Komla AIn today's electricity supply industry, demand side participation is considered an important factor that can influence the market performance and output effectively. Demand elasticity shows the sensitivity of demand side to the market price, and thus can provide potential adjustment of demand in the market. The purpose of this research is to study the impact of demand elasticity on power producers 'market competition output. An analytical model, called "Extended Cournot model" is developed in this thesis based on the classical Cournot model. Through the integration with conjectural variation model, in which power producers consider both the generation and price level, the extended Cournot model can analyze electricity market results under the conditions of different constraints. In the classical Nash Cournot model, capacity withdrawal exists in most cases especially when transmission constraint occurs. In contrast, the newly developed analytical model ensures that demand is always satisfied at all time. Demand elasticity is incorporated directly into the market results calculation instead of using the market clearing price. This approach enables the load demand to directly obtain the market results by tuning its demand elasticity. The intention is to show that demand side should be more encouraged to participate in the market competition. In the classical economic dispatch, the load demand is highly inelastic. From the load curve, there is only a change of physical volume of demand. The demand responsiveness, which is represented by demand elasticity, has been understated. In this thesis, the hypothesis is that demand elasticity and system constraint have critical influence on the power producers' competition results in terms of market clearing price, individual output and profit. Load demand can make use of demand elasticity to affect its final payment to the market. Such ability is expected to be limited in the case where system constraints, i.e. generation limits and transmission limits, exist. For simplicity, a small network and number of power producers are used in this thesis to investigate the effectiveness of the Extended Cournot model. However, this model can be applied to more complex networks with different market environments.