Light-field imaging and holographic imaging are currently the two mostly investigated 3-D imaging technologies because of their potentials to create the viewing environment conforming to a natural viewing condition. The basic optical geometries for image display in these imaging are not different from that of integral photography. The images in the two type of imaging are a set of different view images. These images are arranged as a 2-D point image array, and each point image is expanded with a certain angle to form a viewing zone. The differences between the two types of imaging are the number of point images in the array and the physical entities forming the images. Holographic imaging has many more point images than light-field imaging, and each image in the array consists of coherent right rays from different positions of an object. In light-field imaging, an array of pixels represents a direction view of the object. Despite these differences, they share the same goal of providing a continuous parallax to viewers and require display panels of almost the same characteristics. It is expected that in the future these two imaging techniques will be integrated into the same flat panel along with the plane image.

Wind power now represents a major and growing source of renewable energy. Large wind turbines (with capacities of up to 6–8 MW) are widely installed in power distribution networks. Increasing numbers of onshore and offshore wind farms, acting as power plants, are connected directly to power transmission networks at the scale of hundreds of megawatts. As its level of grid penetration has begun to increase dramatically, wind power is starting to have a significant impact on the operation of the modern grid system. Advanced power electronics technologies are being introduced to improve the characteristics of the wind turbines, and make them more suitable for integration into the power grid. Meanwhile, there are some emerging challenges that still need to be addressed. This paper provides an overview and discusses some trends in the power electronics technologies used for wind power generation. First, the state-of-the-art technology and global market are generally discussed. Several important wind turbine concepts are discussed, along with power electronics solutions either for individual wind turbines or for entire wind farms. Some technology challenges and future solutions for power electronics in wind turbine systems are also addressed.

Three-dimensional imaging is still not in the full commercial stage, but its application is widening due to its capability of creating real-world-like environments. This capability is especially important in realizing reality communication and telepresence operations in medical and unreachable places. For these applications, technologies for interacting with objects in the 3-D image should also be developed. The widespread use of 3-D images is expected in near future, but before that, problems of minimizing physical stresses, especially eye fatigue, should be solved for 3-D imaging. Currently, expected solutions to the problems are electroholography and super multiview methods. These two methods work at different principles, but they both can provide the continuous parallax as in the real-world scenes/objects. Electroholography can also provide focusable depth information to the viewers, though its viewing zone angle is limited. For the super multiview, it is not apparent that it can provide the focusable depth information, but it can provide more comfortable viewing condition than the holography because of its wider viewing zone angle.

The essential components of generating three-dimensional (3-D) images are defined, and various methods of creating each of the components are explained. The components are image acquisition, image multiplexing and processing, and display mechanisms. For image acquisition, transforming, synthesizing based on disparity, voxel and wavefront deformation, and sampling and photographing methods are used. For multiplexing, time, spatial, and spatiotemporal, and for processing, chirping, layering, and pixel cell based multiview image arrangement methods are used. The display mechanisms are classified into projection, contact,and scanning types depending on their means of displaying images. From these methods, 3-D images with real volume, with parallax only and with psychologically induced depth sense can be generated. The display mechanisms have another important mission of creating viewing zones. For this purpose, all 3-D imaging methods employ a special form of optics or mechanisms complying with their image multiplexing schemes. These optics and mechanisms are essential in realizing 3-D imaging systems but at the same time they provide many unfriendly and uncomfortable effects to viewers, and also impose some functional limitations.