I can refer you to some papers which I have published on the analysis and design of tubular(cylindrical) linear motors.

.(1) "Electric Tubular Actuator with Composite Rotor"., By: M.A.Saleh, M.F.Sakr, S.M.Ali and A.A.Fahim, Proc. of International Conference on Electric Machines, Brussel, Sept, 1978.

(2) "Numerical Solution of Fields and Forces in Tubular Induction Actuator with Composite Rotor"., By: M.A.Saleh, S.M.Ali and A.A.Fahim, Proc. of International Conference on Electric Machines, Brussel, Sept, 1978

(3) "Electric Tubular Motor with Composite Rotor", By: M.A.Saleh M.F.Sakr, S.M.Ali and A.A.Fahim, Electric Power Components and Systems, USA, Vol. 4, No. 1, 1979.

(4) "Numerical Analysis of Tubular Induction Motor with Composite Rotor", By: M.A.Saleh, S.M.Ali and A.A.Fahim, Electric Power Components and Systems, USA, Vol. 4, No. 2, 1979.

(5) "Electric Tubular Motor with Composite Rotor", By: M.A.Saleh M.F.Sakr, S.M.Ali and A.A.Fahim, Electric Power Components and Systems, USA, Vol. 4, No. 1, 1979.

(4)"Analysis of Tubular Induction Servomotors", By: M.S.Saleh, W.H.A.Shohoud, H.E.A.Khashab, Armed Forces Scientific Research Bulletin, Vol. XIII, No. 28, 1981.

(6) An approach to the Design of Tubular Actuators with Composite Secondary", By: M.A.Saleh, F.A.Zaher, A.A.Fahim, Proceedings of the International Conference on Electrical Machines ICEM-IV Budapest, 1982.

(7). An Investigation of the Segmented-Secondary Linear Reluctance Motor"., By: A.M.Maky, A.M.Sawy, M.A.Saleh, Proceedings of the International Conference on Electrical Machines ICEM-IV Budapest, 1982

(8). "An Approach to the Design of Tubular Induction Actuators with Composite Secondaries", By M.A.Saleh, Al.L.Day and A.A.Fahim, IEEE-PES Midwest Power Symposium, Madison, Wisconsin USA, 1982.

(9) "Finite Element Analysis of Linear Tubular Motor With Composite Rotor", By: A.A.Fahim and M.A.Saleh, IMACS TC-1 Symposium on Modelling and Simulation of Electrical Machines and Converters, Liege-Belgium, May 1984