🔬 科学与工程Science & Engineering （第 4 页）(page 4)
混凝土砌块计算器（墙体、门窗扣除、损耗）Concrete Block Calculator (Wall, Openings, Waste)
输入墙长和墙高（或直接输入面积），扣除门窗洞口，按所选砌块规格（含灰缝）算出需要的砌块数、加损耗后的订购数和行数，支持公制和英制。本地处理。Enter the wall length and height (or the area), take off door and window openings, and get the number of blocks for the chosen size including mortar joints, the order quantity with waste and the number of courses, in metric or imperial. Processed locally.
直流线径计算器（按压降选线，mm² / AWG）DC Wire Size Calculator (by Voltage Drop, mm² and AWG)
输入直流电压、电流、单程线长、允许压降百分比和导体材料（铜或铝），按往返回路电阻算出所需的最小截面积，并推荐下一档标准公制截面和 AWG 线号，同时给出实际压降和线损功率。适用于太阳能、汽车、房车等低压直流线路。本地处理。Enter the DC voltage, current, one-way cable length, allowed voltage drop and conductor (copper or aluminium) to get the minimum cross-section from the round-trip resistance, the next standard metric size and AWG gauge, and the resulting voltage drop and power loss. For solar, automotive, RV and other low-voltage DC runs. Processed locally.
密度高度计算器（含高度表拨正、露点）Density Altitude Calculator (with Altimeter Setting and Dew Point)
输入机场标高、高度表拨正值和气温（可选露点），先求气压高度，再按国际标准大气从空气密度求出密度高度；同时给出常用的“每高于标准温度 1 °C 加 120 英尺”经验值和 ISA 温度偏差。仅供学习，飞行请使用经批准的性能资料。本地处理。Enter the field elevation, altimeter setting and temperature (and optionally the dew point) to get the pressure altitude and then the density altitude from the air density in the International Standard Atmosphere, alongside the common 120 ft per °C rule of thumb and the ISA deviation. For learning; use approved performance data for flight. Processed locally.
稀释比例计算器（1:n 配比、C₁V₁ = C₂V₂）Dilution Ratio Calculator (1:n Mixing, C₁V₁ = C₂V₂)
三种算法：按 1:n 的稀释比和想要的总量算出原液和水各需多少（可选“1 份原液 + n 份水”或“原液占总量 1/n”两种说法）；由已知原液和水的体积求比例与浓度；或用 C₁V₁ = C₂V₂ 求需要的原液体积。本地处理。Three ways: from a 1:n ratio and the total you want, get how much concentrate and water to use (as 1 part concentrate plus n parts water, or concentrate as 1/n of the total); from known volumes, get the ratio and strength; or use C₁V₁ = C₂V₂ to find the concentrate volume. Processed locally.
位移计算器（匀加速运动四种公式）Displacement Calculator (Constant Acceleration, Four Equations)
匀加速直线运动的位移：由初速度、加速度和时间 (s = v₀t + ½at²)；由初速度、末速度和时间 (s = (v₀ + v)t/2)；由初速度、末速度和加速度 (s = (v² − v₀²)/2a)；或由末速度、加速度和时间。同时补齐其余未知量。本地处理。Displacement under constant acceleration from initial velocity, acceleration and time (s = v₀t + ½at²), from initial and final velocity and time (s = (v₀ + v)t/2), from both velocities and acceleration (s = (v² − v₀²)/2a), or from final velocity, acceleration and time, filling in the other unknowns too. Processed locally.
墙体龙骨计算器（立柱、上下梁板、门窗、转角）Wall Framing Calculator (Studs, Plates, Openings, Corners)
输入墙长、立柱间距（16/24 英寸或 400/600 毫米）、门窗洞口数和转角数，估算需要的立柱数量、上下梁板（单底板 + 双顶板）总长度和所需板材根数，并加上损耗。支持英尺和米。本地处理。Enter the wall length, stud spacing (16 or 24 in, or 400 or 600 mm), the number of openings and corners to estimate the studs, the total plate length (single bottom plate plus double top plate), the number of plate boards and waste. Works in feet or metres. Processed locally.
振动加速度/速度/位移换算Vibration Acceleration / Velocity / Displacement Calculator
按正弦振动关系在频率、加速度、速度、位移之间换算：填任意两项即可算出其余各项，同时给出峰值、有效值（RMS）和峰峰值，支持 m/s²、g、mm/s、μm 等单位。Convert between frequency, acceleration, velocity and displacement for sinusoidal vibration: fill in any two and get the rest as peak, RMS and peak-to-peak values, in m/s², g, mm/s, μm and more.
国际单位制词头换算SI Prefix Converter
在全部 24 个国际单位制（SI）词头之间精确换算，从昆它 Q（10³⁰）到亏科托 q（10⁻³⁰），例如 2.5 GHz = 2500 MHz、470 nF = 0.47 μF，采用十进制精确计算无浮点误差。Convert exactly between all 24 SI prefixes, from quetta Q (10³⁰) to quecto q (10⁻³⁰) — e.g.