All the pressure

我制定了一个详细的学习计划,包括早晨锻炼、写日记、阅读中文书籍、自由时间(不玩游戏)、数学阅读和观看英语电视节目。虽然看起来任务繁重,但我决心尽力完成。如果想了解下午的学习安排,请订阅,明天我会继续分享。

I’ve right down my study plan. (pressure homework) It’s simple, I’ll be tired when I’m done. This is the plan:
7:00~8:00 do morning exercises/play sports
8:05~8:25 diary
8:30~9:00 read Chinese book
9:05~10:00 free (no games)
10:05~11:00 read math book
11:05~12:00 watch English TV
This is the morning study plan, it looks like a lot, but I’ll try to succeed it, if you want to know the afternoon part, then subscribe, I’ll write it tomorrow.

To avoid collapse, the bias voltage should be one third of the pull-in voltage[1]. The input sound pressure level (input SPL) is defined as the ratio of the audible sounds captured by the microphone (P1) to the lowest pressure detected by human hearing (P2 which is 20 µPa)[1]: inputSP L = 20logP1 P2  (5) The resonance frequency ( defined by the membrane radius, the membrane pretension η0, the membrane mass density ρ, and the membrane thickness) will limit the upper bandwidth. f0 ≈ 2.4 2πrrη0 ρt (6) Furthermore, the dominant noise mechanism is the squeezed-film effect due to damping of air which depends on the size of the acoustic holes. The noise floor will affect the minimum detectable sound level that will be captured by the microphone[1]. Therefore, it is possible to define an electroacoustical sensitivity that will obey the following equation[1]: Se = Vbias g (7) Where Vbias is the bias voltage. The bias voltage and the thickness of the air gap will affect the electrical sensitivity, but the bias voltage in turn depends on g. The variation of the air gap pressure will affect the mechanical sensitivity of the system[1]. Furthermore, the displacement (which depends on the membrane rigidity) will have an impact on the definition of the sensitivity. If a circular membrane is of interest, the mechanical sensitivity will be equal to: Sm = R2 mem 8σ0h = ∆g ∆P (8) Where Rmem is the membrane radius, σ0 is the residual tensile stress, h is the membrane thickness, ∆g is the air gap change, and ∆P is the change in pressure. Therefore, the total sensitivity (given by the product of the electrical and mechanical sensitivity) will depend on all the design parameters (the air gap, the membrane radius that will define its area, and the membrane thickness). S = Vbias g R2 mem 8σ0h (9) The parameter that defines whether a microphone can detect sound waves from all directions or from a specific direction is called directionality. The directional pattern can be graphically represented by a polar pattern. Omnidirectional microphones are able of equally detecting sound waves from all directions. Conversely, directional microphones show the strongest output when sound waves arrive on a single axis (which is parallel or vertical to the moving membrane surface). In the human auditory system, the eardrums act like a membrane. This diaphragm is approximately 100 µm thick. This limits the flat frequency response to 2 kHz and imposes a detection limit at 20 kHz. On the other hand, thinner and lighter membranes allow for better detection of sound waves at high frequency
08-29
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