Friend or Foe: Perceptions of China in Africa

China\u27s rush to Africa for resources and a sphere of influence has inspired much debate in the academic world. Many western scholars generalize China\u27s Africa strategy or African perceptions of that strategy. These are both grave mistakes. While China\u27s objectives in Africa are the same all over, the way it achieves that strategy varies from nation to nation. In addition, African perceptions of China vary from nation to nation. Using Algeria and Niger as main case studies, this paper will show that the wealth of a nation changes the way that the Chinese government and Chinese nationals interact with that nation, and, that this modification of behavior is what causes positive or negative perceptions of China

A brief summary of the attempts to develop large wind-electric generating systems in the US

Interest in developing large wind-electric generating systems in the United States was simulated primarily by one man, Palmer C. Putnam. He was responsible for the construction of the 1250 kilowatt Smith-Putnam wind-electric plant. The existence of this system prompted the U. S. Federal Power Commission to investigate the potential of using the winds as a source energy. Also, in 1933 prior to Putnam's effort, there was an abortive attempt by J. D. Madaras to develop a wind system based on the Magnus effect. These three projects comprise the only serious efforts in America to develop large wind driven plants. In this paper the history of each project is briefly described. Also discussed are some of the reasons why wind energy was not seriously considered as a major source of energy for the U. S

A method for predicting interfacial freezing of a liquid flowing over a cold surface

Instantaneous thickness of a frozen layer is a function of specific heat, heat of fusion, temperatures, the frozen layer thickness at equilibrium, the thermal conductivity, and heat transfer coefficient. The equation can be evaluated on a desk calculator

Simulated fuel assembly Patent

Simulated fuel assembly-type flow measurement apparatus for coolant flow in reactor cor

Summary of tower designs for large horizontal axis wind turbines

Towers for large horizontal axis wind turbines, machines with a rotor axis height above 30 meters and rated at more than 500 kW, have varied in configuration, materials of construction, type of construction, height, and stiffness. For example, the U.S. large HAWTs have utilized steel truss type towers and free-standing steel cylindrical towers. In Europe, the trend has been to use only free-standing and guyed cylindrical towers, but both steel and reinforced concrete have been used as materials of construction. These variations in materials of construction and type of construction reflect different engineering approaches to the design of cost effective towers for large HAWTs. Tower designs are the NASA/DOE Mod-5B presently being fabricated. Design goals and requirements that influence tower configuration, height and materials are discussed. In particular, experiences with United States large wind turbine towers are elucidated. Finally, current trends in tower designs for large HAWTs are highlighted

Experimental profiles of velocity components and radial pressure distributions in a vortex contained in a short cylindrical chamber

Velocity components and radial pressure distributions in vortex contained in short cylindrical chambe

Status of wind-energy conversion

The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems; a sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to: (1) fossil fuel systems; (2) hydroelectric systems; or (3) dispersing them throughout a large grid network. Wind energy appears to have the potential to meet a significant amount of our energy needs

Le sfide della mobilit\ue0 sostenibile in una montagna diversa

While an approach far sustainable development get more diffused in policies as well as in planning interventions, deep changes have interested Alpine mountain regions. lf some valleys and highlands stili remain little accessible and affected by a not very developed and modernised economy, a large part of the Alpine arch recorded a really significant progress due to new infrastructures, technological innovation and tourism development. Above all, tourism has been such a trigger of new economie activities, occupation increasing and visitors attraction. Winter sport or summertime leisure actvities, supported by modem (mostly vehicular) mobility and high-impacting infrastructures cause enrichment but also congestion, new forms of soil consumptions and progressive environmental and landscape deterioration. The unavoidable challenge far the future is then the promotion of new form of mobility, which could favour the highest modal integration and a conditioned and limited accessibility, which will help to preserve precious environmental resources although supporting development

Insight into CO2 dissociation in plasmas from numerical solution of a vibrational diffusion equation

The dissociation of CO2 molecules in plasmas is a subject of enormous importance for fundamental studies and the recent interest in carbon capture and carbon-neutral fuels. The vibrational excitation of the CO2 molecule plays an important role in the process. The complexity of the present state-to-state (STS) models makes it difficult to find out the key parameters. In this paper we propose as an alternative a numerical method based on the diffusion formalism developed in the past for analytical studies. The non-linear Fokker-Planck equation is solved by the time-dependent diffusion Monte Carlo method. Transport quantities are calculated from STS rate coefficients. The asymmetric stretching mode of CO2 is used as a test case. We show that the method reproduces the STS results or a Treanor distribution depending on the choice of the boundary conditions. A positive drift, whose energy onset is determined by the vibrational to translational temperature ratio, brings molecules from mid-energy range to dissociation. The high-energy fall of the distribution is observed even neglecting VT processes which are normally believed to be its cause. Our study explains several puzzling features of previous studies, provides new insights into the control of the dissociation rate and a much sought compression of the required data for modeling