Optimized Design of 8-Figure Null-Flux Coils in EDS Maglev.
The 8-figure null-flux ground coils in EDS (Electro-Dynamic Suspension) including the PLG (combined Propulsion, Levitation and Guidance) system, which can both suspend and propel maglev vehicles simultaneously, have mainly longitudinal and vertical dimensions such as coil pitch and heights of upper and lower coils. In this paper we investigate these dimensions not only to balance the basic performance for levitation, guidance and propulsion, but also to reduce magnetic disturbance of superconducting magnet. By using an optimization program, we induced the relationship between the basic performance and these dimensions. Furthermore, by implementing a modal analysis, we predicted the vibration of superconducting magnet in different pitches, and thereby proposed these dimensions to decrease the vibration.
Characteristics of LSM combined propulsion, levitation and guidance
In commercializing the superconducting maglev system, it is important to reduce the cost, especially that of ground coils installed all along the guideway. The ground coils designed for Yamanashi test track under construction are composed of both octagonal-shaped null-flux coils for EDS (Electrodynamic Suspension) and double-layered armature coils of LSM (Linear Synchronous Motor). The former reduces the magnetic drag of the running resistance, and the latter reduces the electromagnetic fluctuation in the superconducting coils. 
 
 
 
In addition, the octagonal-shaped coils can generate propulsion force by being connected to the power supply. This system can generate levitation force, guidance force and propulsion force by the same ground coils. Therefore this system is expected to reduce the cost of ground coils, the number of which is decreased. 
 
 
 
This paper presents the principle and analytical formula of the combined propulsion, levitation and guidance system (PLG system), including one for angles. In addition, using numerical examples, the characteristics of this system are expressed.
THE ATLANTIC SLAVE TRADE AND COLONIALISM: REASONS FOR AFRICA’S UNDERDEVELOPMENT?
It is probably an understatement to assert that Africa, the world’s second largest continent, is underdeveloped compared with other continents. Two major exogenous factors often cited for Africa’s development crisis are the so called ‘dual historical injustices’ – the Atlantic slave trade and colonialism. It is often pointed out that while the former almost completely arrested and retarded Africa’s demographical growth for more than three centuries, evoked a perennial state of acrimony and warfare and created a tense and unprecedented atmosphere of insecurity which hindered economic activities and stifled local entrepreneurship and technological drive and dislocated Africa’s socio-economic and political structures and institutions; the latter tied African countries to the apron strings of western imperial powers thereby rendering the pre-conditions necessary for socio-economic and political transformation unachievable. This paper contends that while the history of Africa’s underdevelopment may be traceable to the Atlantic slave trade and colonialism, African leaders had made enormous contributions to the continent’s underdevelopment and backwardness. The paper concludes that irresponsible and irresponsive leadership, vampirism and prodigality, corruption, lack of respect for democratic ideals, insecurity, endemic civil wars, nepotism, etc are the fundamental causes of Africa’s underdevelopment.