英语论文网

fter the separation efficiency of the railway industry change.
In the vertical structure, the assumption is that the upstream enterprise according to the linear pricing to the downstream enterprises collect the Internet use, its price for , C for upstream service unit cost. The downstream operators will pay network fee as operating costs included in the price. Here is the need to pay attention to, upstream of the profits of the business only to provide services related to the number, the downstream enterprise each additional sales network managers increase profits profits. The downstream operators in the face of the demand curve is right to tilt, this means that raise prices will reduce the number of sales. Here in order to simplify, assuming that the demand of the market function is and upstream service unit cost .
First of all, we discuss the original natural monopoly market structure, enterprise in order to pursue their own profit maximization, enterprise can provide the service quantity and price. For the net transport integrated enterprise, it cost is c, and it from the railway transport industry customers with service unit price for . This enterprise in the face of market demand function is above hypothetical market demand function . The enterprise profits for:

For enterprise profit maximization, ，
The available:
So in the integration of transport and natural monopoly market structure, the monopoly in achieve their profit maximization conditions can provide transportation service quantity unit number for unit quantity price for .
Then we discuss a network transport separate situation:
Assume that there is only one operator to provide transportation, first on the downstream operators profits for:

Required to maximize profits, the derivative of :
Solving was:
.
In the upper reaches of the network managers also maximize profit, will above operators solution substitution network management profit function get:

Derivative of the profit function in accordance with the principle of profit maximization requires , Calculated, to get the results and the downstream operators into the price, quantity, get:
And the whole industry get profits for:
Can see that: although network and operation of separation, but the number of the services they provide not only did not increase but reduce the unit price, service products also increased. It can be seen in this market structure the level of social welfare not only has not been improved, but has been damaged. Does that mean that network transport separation reform is not necessary? Of course, the answer is negative, the net transport is the purpose of the separation will be competitive transportation business and still have natural monopoly characteristics of the railway network business separated . We can notice that, originally in the net transport integration, we cannot confirm which part is the competitive transportation business creation, or the natural monopoly characteristics of the railway network business produce, so regulators can not be very good to impose controls, and will now two parts, it is easy to regulation of different enterprises of different control methods, so as to realize the maximization of social welfare control target .