Tham khảo tài liệu 'thiên cầu', tài liệu phổ thông, vật lý phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

Tham khảo tài liệu 'thiên văn học và những mốc lịch sử đáng chú ý nhất', tài liệu phổ thông, vật lý phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

Sự so sánh về độ bền phá huỷ, phá huỷ trượt do kéo và độ bền riêng của các HKVĐH khác nhau từ các nguồn tham khảo đã có

Khi truyền từ một môi trường này sang một môi trường khác (có chiết suất khác nhau), ánh sáng sẽ bị phản xạ và khúc xạ ở mặt phân cách hai môi trường, nghĩa là tia sáng bị gãy khúc. Vậy trong trường hợp chung, giữa hai điểm cho trước ánh sáng có thể truyền theo đường ngắn nhất không? Ta hãy khảo sát thí nghiệm sau:

This chapter introduces issues concerning unsteady flow, i.e. flow situations in which hydraulic conditions change with time. Many flow phenomena of great importance to the engineer are unsteady in character, and cannot be reduced to steady flow by changing the viewpoint of the observer. The equations of motion are formulated and the method of characteristics is introduced as main part of this chapter. The concept of positive and negative waves and formation of surges are described. Finally, some solutions to unsteady flow equations are introduced in their mathematical concepts.......

The term "transition" is introduced whenever a channel's cross-sectional configuration (shape and dimension) changes along its length. Beside it, in the water control design, engineers need to provide for the dissipation of excess kinetic energy possessed by the downstream flow. Formulas for design calculation of transition works and energy dissipators are presented in this chapter

Spillways are familiar hydraulic structures built across a stream to control the water level. This chapter emphasizes the classification of weirs and spillways as well as the application of hydraulic formulas for designing their shape and dimensions.

Linking up with Chapter 2, dealing with uniform flow in open channels, it may be noted that any change in the flow phenomenon (i.e. flow rate, velocity, flow depth, flow area, bed slope do not remain constant) causes the flow to be non-uniform. This chapter will discuss the effect of change in any one of the above quantities, including specific energy, critical depth and slope, and flow types. How to draw water surface profiles will also be introduced.

In this chapter, the specific-energy concept is introduced and, then, the momentum principle is applied to open-channel flows. The hydraulic jump and its types are defined and classified. This chapter introduces how to determine the direct and submerged hydraulics jump; their characteristics are presented

The chapter on uniform flow in open channels is basic knowledge required for all hydraulics students. In this chapter, we shall assume the flow to be uniform, unless specified otherwise. This chapter guides students how to determine the rate of discharge, the depth of flow, and the velocity. The slope of the bed and the cross-sectional area remain constant over the given length of the channel under the uniform-flow conditions. The same holds for the computation of the most economical cross section when designing the channel. The concept of permissible velocity against erosion and sedimentation is introduced.......

This lecture note is written for undergraduate students who follow the training programs in the fields of Hydraulic, Construction, Transportation and Environmental Engineering. It is assumed that the students have passed a basic course in Fluid Mechanics and are familiar with the basic fluid properties as well as the conservation laws of mass, momentum and energy. However, it may be not unwise to review some important definitions and equations dealt with in the previous course as an aid to memory before starting.......

The subject of Open Channel Hydraulics for Engineers, also called Applied Hydraulics, is a subject required not only for Hydraulic Engineering students but also for other engineering fields involved, such as Construction Engineering, Transportation Engineering and Environmental Engineering. It follows the previous subject named Fluid Mechanics. The knowledge of open-channel hydraulics, which is essential to the design of many hydraulic structures, has made advances by leaps and bounds.

Thế giới tự nhiên, xét về mặt vật lý, là một bức tranh gồm ba phần: Vi mô, vĩ mô và siêu vĩ mô. Siêu vĩ mô có nghĩa là vô cùng to lớn theo không gian và thời gian. Thiên văn là một môn học về thế giới siêu vĩ mô đó. Cùng với các phần học khác của vật lý, thiên văn giúp chúng ta có được một bức tranh toàn diện về thế giới tự nhiên. Thiên văn là một môn học rất cổ điển, nhưng đồng thời cũng rất hiện đại.......

The main objective of the doctoral research was to improve the performance in Physics and Mathematics, at Advanced Level Examinations, of two rural girls’ secondary schools in Arua (Muni and Ediofe) through application of e-learning. Both schools have no functional science laboratories and libraries. They also have no qualified and committed teachers who can competently teach at that level of education. The research included participatory action research methodology and the use of interactive multimedia CD-ROMs for Physics and Mathematics as the main course delivery platform. During the study, twenty nine female students from the two schools effectively used the hybrid e-learning tools and applications for six months in 2007......

Bài này được tác giả giới thiệu về ngành thiên văn học, nguyên bản bằng tiếng Anh.Rất thích hợp cho các ban đam mê học tiếng ANh