Abstract: A protective helmet, such as an antivirus helmet with a viewing window completely encloses the user's head. The entire helmet is airtight except for an air inlet and air outlet on its side wall. In order to prevent the viewing window from fogging by the user's exhaled gas, the window is made of sandwich glass with central heater wire to warm the glass. The air needed for the user to breathe is supplied by an external high pressure air reservoir. The air undergoes a pressure reduction and cooling process. Such an antivirus helmet provides safe and comfortable air for medical staff to breathe during their work in an infectious disease ward.

Abstract: A set of new accessories for the violin family instrument, switch fingerboards, which includes an assembly of switches, suitable for violin learners. Switches are laid out regularly on the spots corresponding to the notes which are written on the fingerboards. Once a switch is turned on (pressed by a finger), a CPU will be triggered, and then output of the signal of a desired pitch will immediately cause the speaker to produce a sound of that pitch. Such a switch fingerboard will surely assist beginners to practice how to stop strings and to shift positions to get pitches more precisely and efficiently. Additionally, an n-like, switch assembly fingerboard is described, where all the switches are embedded into a rectangular plate in equal intervals. With the same CPU, ROM, amplifier and speaker system, any sound recorded from a performance in the violin family, corresponding to each note, can be replayed on command.

Abstract: A set of new accessories for the violin family instrument, switch fingerboards, which includes an assembly of switches, suitable for violin learners. Switches are laid out regularly on the spots corresponding to the notes which are written on the fingerboards. Once a switch is turned on (pressed by a finger), a CPU will be triggered, and then output of the signal of a desired pitch will immediately cause the speaker to produce a sound of that pitch. Such a switch fingerboard will surely assist beginners to practice how to stop strings and to shift positions to get pitches more precisely and efficiently. Additionally, an n-like, switch assembly fingerboard is described, where all the switches are embedded into a rectangular plate in equal intervals. With the same CPU, ROM, amplifier and speaker system, any sound recorded from a performance in the violin family, corresponding to each note, can be replayed on command.

Abstract: An angular momentum spinner includes two or more rotating arms loaded with an adjustable sliding block for each arm and laid symmetrically about a rotating center. Each sliding block is controlled to move along the corresponding rotating arm. Such a spinner can display the conservation of angular momentum vividly and intuitively, and can also serve as an amusing toy for children. The spinner can be used as teaching equipment for various students to demonstrate the theorem of angular momentum conveniently, intuitively and amusingly.

Abstract: An angular momentum spinner includes two or more rotating arms loaded with an adjustable sliding block for each arm and laid symmetrically about a rotating center. Each sliding block is controlled to move along the corresponding rotating arm. Such a spinner can display the conservation of angular momentum vividly and intuitively, and can also serve as an amusing toy for children. The spinner can be used as teaching equipment for various students to demonstrate the theorem of angular momentum conveniently, intuitively and amusingly.

Abstract: A frame for an automobile windshield and side windows with improved visibility is formed by a plurality of hollow quadrangular prisms. Each hollow quadrangular prism includes four rigid right triangular prisms laid symmetrically in a V-like shape, two on each side of the V. Each rigid right triangular prism has a base triangle which is an obtuse and scalene triangle, and front and rear lateral faces which are covered with a reflective material of visible light. The front and rear lateral faces of the four right triangular prisms face each other forming a channel between them, which is filled with a transparent material. The hollow quadrangular prism reflects incident light in sequence by the reflective lateral faces of right triangular prisms. Many hollow invisible quadrangular prisms are stacked up to form a pillar for an automobile.

Abstract: Frames for an automobile windshield and side windows with improved visibility is formed by a plurality of hollow quadrilateral prisms. Each hollow quadrilateral prism includes four rigid right triangular prisms laid unsymmetrically in a V-like shape, two on each side of the V. Each rigid right triangular prism has a base triangle which is an obtuse and scalene triangle, and front and rear lateral faces which are covered with a reflective material of visible light. The front and rear lateral faces of the four right triangular prisms face each other forming an unsymmetrical channel between them, which is filled with a transparent material. The hollow quadrilateral prism reflects incident light in sequence by the reflective lateral faces of right triangular prisms. Many hollow invisible quadrilateral prisms are stacked up to form pillars for an automobile.

Abstract: Frames for an automobile windshield and side windows with improved visibility is formed by a plurality of hollow quadrilateral prisms. Each hollow quadrilateral prism includes four rigid right triangular prisms laid unsymmetrically in a V-like shape, two on each side of the V. Each rigid right triangular prism has a base triangle which is an obtuse and scalene triangle, and front and rear lateral faces which are covered with a reflective material of visible light. The front and rear lateral faces of the four right triangular prisms face each other forming an unsymmetrical channel between them, which is filled with a transparent material. The hollow quadrilateral prism reflects incident light in sequence by the reflective lateral faces of right triangular prisms. Many hollow invisible quadrilateral prisms are stacked up to form pillars for an automobile.

Abstract: A frame for an automobile windshield and side windows with improved visibility is formed by a plurality of hollow quadrangular prisms. Each hollow quadrangular prism includes four rigid right triangular prisms laid symmetrically in a V-like shape, two on each side of the V. Each rigid right triangular prism has a base triangle which is an obtuse and scalene triangle, and front and rear lateral faces which are covered with a reflective material of visible light. The front and rear lateral faces of the four right triangular prisms face each other forming a channel between them, which is filled with a transparent material. The hollow quadrangular prism reflects incident light in sequence by the reflective lateral faces of right triangular prisms. Many hollow invisible quadrangular prisms are stacked up to form a pillar for an automobile.