Flue gas desulphurization gypsum (FGD) is a kind of industrial waste derived from the treatment of sulfur dioxide gas generated by power plants and oil refinery factories． The effect of different calcination temperature and the maintaining time at certain temperature was studied． Based on this， mineral additives and chemical activators were added to modify the composite cementitous system． The results show that the appropriate calcination temperature and maintaining time， suitable amount of mineral additives and chemical activators are all able to improve the compressive strength of the system， thus， they are all effective ways to modify the properties of this composite．

A method of simulation on PLC controlled objects based on configuration software through computer was presented to solve the problems of PLC control system's debugging. Framework of the simulation system, principle of the simulation system design, and the development process were described in detail. 

A fuzzy evaluation method of dust removing effect in cement production was presented based on fuzzy analysis． Taking effective factors as fuzzy parameters, dust removing effect was evaluated by using fuzzy math theory． Simple factor evaluation was taken according to subordinated function before making comprehensive evaluation by weight． A difficulty quantitative evaluation was changed into quantitative result by using fuzzy transform．

Wear mechanism and repair technology on roller surface of roller press is analyzed． Comparison is made on using imported welding stick and flux－cored electrode ZD for roller surface repair． It is emphasized that using local made welding stick on roller surface repair is more important and necessary for roller press purchased from abroad．