Whether an item is popular or not depends largely on its cost performance. For manufacturers, it is very important to create the most high-quality items with the least amount of money. For example, in the case of the same material, what kind of bridge structure is the most material-saving and long-life, what specific design can make the car more fuel-efficient and faster, and what kind of special pipeline design can make the flow of water resources more efficient are problems that manufacturers need to constantly explore, and fluid mechanics can help and solve these problems to a large extent. This paper mainly introduces the application of fluid mechanics in bridge engineering, automobile design, and agricultural production. The author analyzes the working principle of fluid mechanics, including some speculations on the future development direction of fluid mechanics.

Dust is a ubiquitous feature of the cosmos, impinging directly or indirectly on most fields of modern astronomy. Dust grains composed of small (submicron-sized) solid particles pervade interstellar space in the Milky Way and other galaxies: they occur in a wide variety of astrophysical environments, ranging from comets to giant molecular clouds, from circum-stellar shells to galactic nuclei. The study of this phenomenon is a highly active and topical area of current research. Dust absorbs optical and Ultraviolet (UV) photons and re-emit them in the infrared. The heating and cooling of dust interact with their environment closely. Dust is closely related to the star formation process, and study on dust could put constraints on the star formation history. While extensively studied in the optical, the extinction property of dust in the UV is still an open question. UV photos are absorbed by earth atmosphere and cannot be accessed from ground-based observations. NASA space mission Galaxy Evolution Explorer (GALEX), on the other hand, provides critical data to this question by surveying the whole sky in two UV bands. By comparing the optical and UV properties of blue and red (dust-absorbed) quasars selected from Sloan Digital Sky Survey (SDSS), we shape the extreme UV dust extinction curve for the first time. The measured UV dust extinction curve will help us characterize the size distribution of dust grains and their compositions which could not be easily accessed by other methods.

It is known well that electricity is an important part of our life and most of it is wasted. However, the natural resources of energy are being wasted and reduced. To utilize the mechanical energy of rotating wheels, in this research report, the device structure of generating electricity voltage is designed, and the relations between the voltage generated by rotating wheels and the geometry and physical parameters of the structures are derived, and the effects of the geometry and physical parameters on the voltage are analyzed. The theoretical results show that the voltages are in proportion to the weight and speed of rotating wheels. The experiments with piezoelectric film and wheels are used to verify the theoretical analysis. The experimental results show that the theoretical analysis is in good agreement with measured results.

The idea of the study was mainly from the concerns about whether wheels of different shapes can also fit well in cars. This paper mainly involves the demonstration of some theoretical features of the Reuleaux triangle and some practical situations of using the triangle as wheels. The aim of the study is to find out some basic features and mathematical rules of the Reuleaux triangle, in addition, the practical uses of this shape will also be studied. In order to learn expertise about this triangle, the author went through papers about geometry and some demonstrations by different mathematicians from different times. The author then made a few assumptions and tried to prove himself to find the rules of this shape more deeply. In conclusion, it found out that the Reuleaux triangle is actually a perfect constant width curve and it can be used as wheels under proper conditions. Apart from that, this paper also concluded an exact method of drawing different constant width curves.