Abstract: A method for controlling an electric heater of a vehicular heating, ventilation, and air conditioning (HVAC) system includes turning on the electric heater; determining whether an ambient air temperature of a vehicle is higher than or equal to a threshold ambient air temperature, and a battery temperature is lower than or equal to a threshold battery temperature; determining whether battery efficiency is lower than or equal to threshold efficiency when the ambient air temperature of the vehicle is higher than or equal to the threshold ambient air temperature, and the battery temperature is lower than or equal to the threshold battery temperature; and turning off the electric heater when the battery efficiency is lower than or equal to the threshold efficiency, wherein the electric heater is configured to receive electric energy from the battery.

Abstract: In a color cathode ray tube, a rectangular panel has a slightly convex outer face with a large radius of outward curvature so as to be almost flat and a concave inner face which satisfies the conditions 0.98<Rh/Rd<1.02, 0.95<Rv/Rd<1.04, 0.98<Rt/Rh<1.02, and 0.98<Rs/Rv<1.05, where Rd is the radius of diagonal curvature along a screen effective surface area, Rt is the radius of a long side peripheral curvature, Rs is the radius of a short side peripheral curvature, Rh is the radius of curvature along the x-axis passing through a center of the screen effective surface area and parallel to the long side, and Rv is the radius of curvature along the y-axis passing through the center of the screen effective surface area and parallel to the short side. Accordingly, distortion of a picture can be minimized by designing the internal curvature of the panel as an optimum shape, and a high picture quality can be obtained.

Abstract: In a color cathode ray tube, a rectangular panel has a slightly convex outer face with a large radius of outward curvature so as to be almost flat and a concave inner face which satisfies the conditions 0.98<Rh/Rd<1.02, 0.95<Rv/Rd<1.04, 0.98<Rt/Rh<1.02, and 0.98<Rs/Rv<1.05, where Rd is the radius of diagonal curvature along a screen effective surface area, Rt is the radius of a long side peripheral curvature, Rs is the radius of a short side peripheral curvature, Rh is the radius of curvature along the x-axis passing through a center of the screen effective surface area and parallel to the long side, and Rv is the radius of curvature along the y-axis passing through the center of the screen effective surface area and parallel to the short side. Accordingly, distortion of a picture can be minimized by designing the internal curvature of the panel as an optimum shape, and a high picture quality can be obtained.