什么是交通流的三相理论，它如何解释高速公路上的幽灵堵车？
What is the three-phase traffic theory and how does it explain phantom jams?
传统模型只有自由流和拥堵两态，三相理论加入同步流作为中间态，车速相近、密度中等但不稳定。微小扰动在同步流中会被放大成局部停走波并向上游传播，于是没有明显原因也会出现堵车。
Classic models have only free and jammed flow; three-phase theory adds an unstable synchronized flow where speeds are similar at medium density. Tiny disturbances amplify into stop-and-go waves propagating upstream, explaining jams with no obvious cause.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Kerner，《交通物理学》（2004）
Kerner, B.S., 'The Physics of Traffic' (2004)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL3476328W：The physics of traffic（
#交通流 #幽灵堵车 #三相
车路协同下的“协同自适应巡航”和单车雷达巡航有何不同，编队行驶能省多少油？
How does cooperative adaptive cruise control under V2X differ from solo radar cruise, and how much fuel can platooning save?
单车巡航只看前车雷达，协同巡航还接收前车加速度广播，反应更快更平顺。多车近距离编队能共享“破风”尾流，卡车编队风阻大降，油耗可省一成到两成。
Solo cruise only sees the front radar; cooperative cruise also gets the leader's acceleration broadcast, reacting faster and smoother. Close platooning shares the slipstream, cutting truck aerodynamic drag so fuel use drops by roughly 10 to 20 percent.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
Shladover，《网联与自动驾驶汽车：过去、现在与未来》（2018）
Shladover, S., 'Connected and Automated Vehicles: Past, Present, and Future' (2018)
#协同巡航 #编队 #空气阻力
在港口集装箱调度中，为什么堆场贝位优化能显著降低龙门吊作业时间？
In port container scheduling, why does yard bay optimization cut gantry crane work time?
集装箱装卸顺序与堆场位置强相关，若出口箱分散在不同贝位，龙门吊要来回长距离移动。通过把同船、同卸序的箱子集中到邻近贝位并按提箱顺序堆垛，能减少倒箱和空驶，从而压缩整体作业时间。
Handling sequence depends heavily on yard location; scattered export boxes force the gantry to travel far. Clustering same-vessel, same-discharge boxes in nearby bays and stacking by retrieval order cuts reshuffles and empty moves, shrinking total handling time.
难度 专业 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
Steenken、Voss & Stahlbock，《集装箱码头运营与运筹学》（2004）
Steenken, Voss & Stahlbock, 'Container Terminal Operation and Operations Research' (2004)
#港口 #调度 #堆场
在轨道交通中，为什么采用再生制动能把列车动能回收成电能？
In rail transit, why does regenerative braking recover kinetic energy as electricity?
列车减速时把牵引电机切换成发电机模式，轮对的转动带动电机发电，产生的电能送回接触网供其他列车使用或存入储能装置。相比单纯用闸瓦摩擦生热，这种方式显著节能并减少磨损。
When slowing, the traction motors switch to generator mode, turning wheel rotation into electricity fed back to the overhead line for other trains or storage. Unlike friction brakes that waste heat, this saves energy and cuts wear.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Iwnicki 编，《铁路车辆动力学手册》（2006）
Iwnicki, S. (ed.), 'Handbook of Railway Vehicle Dynamics' (2006)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-429-89062-8 (2nd ed., CRC Press, 2019)
#再生制动 #节能 #轨道
自动驾驶为什么需要融合多种传感器？融合通常在什么层级进行？
Why must autonomous driving fuse multiple sensors, and at which levels is fusion typically performed?
单一传感器都有盲区：摄像头对光线敏感、测距不精确，毫米波雷达分辨率低、难以分辨静止物体，激光雷达昂贵且受雨雾影响。多传感器融合利用各自的互补性，在时间同步和空间对齐（外参标定）的前提下，把检测结果或原始数据组合成统一的环境模型。融合可分为数据级、特征级和目标级三类，目标级融合把各传感器识别出的目标关联匹配后合成航迹，鲁棒性高、计算量可控，是主流方案。
Every sensor has blind spots: cameras are light-sensitive and poor at ranging, mmWave radar has low resolution and trouble with stationary objects, and LiDAR is costly and degraded by rain and fog. Sensor fusion exploits their complementarity, combining detections or raw data into one environmental model after time synchronisation and spatial calibration. Fusion happens at data, feature or object level; object-level fusion matches and merges the targets each sensor detects into unified tracks, offering high robustness at manageable compute cost and is the mainstream approach.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Maurer、Gerdes、Lenz & Winner，《自动驾驶：技术、法律与社会视角》（Springer, 2016）
Maurer, Gerdes, Lenz & Winner, 'Autonomous Driving: Technical, Legal and Social Aspects' (Springer, 2016)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-3-662-45854-9 / DOI 10.1007/978-3-662-45854-9 (
#感知融合 #自动驾驶 #传感器
整车控制器（VCU）在电动汽车中承担什么角色？如何根据踏板信号决定扭矩请求？
What role does the vehicle control unit (VCU) play in an EV, and how does it determine torque demand from pedal signals?
VCU是整车动力系统的决策中枢，采集加速和制动踏板、挡位、车速、电池及电机状态等信息，根据驾驶员意图和车辆安全边界计算电机扭矩指令并下发给电机控制器。扭矩请求综合考虑踏板开度与速率、当前车速和电池允许功率：低速起步大扭矩、高速适度降扭，同时必须受电机峰值扭矩特性和电池放电能力约束，并协调能量回收制动与液压制动的分配。
The VCU is the decision centre of the EV powertrain: it reads the accelerator and brake pedals, gear, vehicle speed, battery and motor states, computes a motor torque command from driver intent and safety limits, and sends it to the motor controller. Torque demand weighs pedal position and rate, current speed, and the battery's allowable power, high torque for launch at low speed and reduced torque at high speed, while always respecting the motor's torque envelope and the battery's discharge capability, and it also arbitrates between regenerative and hydraulic braking.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
SAE International 汽车工程手册（Bosch《汽车手册》）；AASHTO《公路与城市道路几何设计》
SAE International; Bosch, Automotive Handbook; AASHTO, A Policy on Geometric Design of Highways and Streets
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL3202243W：A policy on geometric d
#整车控制器 #扭矩管理 #电动汽车
eVTOL（飞行汽车）靠多旋翼垂直起降，它在城市空域面临的最大工程与安全难点是什么？
eVTOL ('flying cars') use multirotors for vertical takeoff—what are their biggest engineering and safety hurdles in city airspace?
难点在电池能量密度有限导致航程短、噪声扰民、以及任何单点失效都要能安全降落。还需低空交通管理和避撞体系，否则密集楼间飞行风险极高。
Limited battery energy density gives short range, noise annoys, and any single failure must still allow safe landing. It also needs low-altitude traffic management and collision avoidance, or dense flight between buildings is too risky.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：本题原挂出处与答案内容不符，已撤回；具体书目待补，暂不展示来源。
本题原挂出处与答案内容不符，已撤回；具体书目待补。
Previous citation withdrawn as unsupported for this answer; a specific source is pending.
#eVTOL #城市空域 #安全冗余
什么是轮胎滑移率？为什么制动力在滑移率约15%至20%时达到最大？
What is the slip ratio of a tyre, and why does braking force peak at a slip ratio of about 15 to 20 percent?
滑移率指车轮在制动或驱动时实际车速与轮速的相对差，纯滚动为0，完全抱死为100%。轮胎与地面的纵向附着力随滑移率先上升后下降，在约15%至20%时出现峰值，之后进入滑动区，附着系数反而降低。ABS把滑移率控制在峰值附近，就是希望始终利用最大附着力，同时保留侧向力能力以维持转向稳定，避免车轮抱死。
Slip ratio is the relative difference between vehicle speed and wheel speed under braking or driving, 0 percent in pure rolling and 100 percent when locked. Longitudinal adhesion between tyre and road first rises with slip, peaks around 15 to 20 percent, then falls as the contact patch slides. ABS holds slip near this peak to use maximum adhesion while retaining lateral force for steering stability, precisely so that the wheels never lock.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
SAE International 汽车工程手册（Bosch《汽车手册》）；AASHTO《公路与城市道路几何设计》
SAE International; Bosch, Automotive Handbook; AASHTO, A Policy on Geometric Design of Highways and Streets
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL3202243W：A policy on geometric d
#滑移率 #轮胎 #ABS
港口自动化集装箱码头为什么多用无人驾驶吊车和AGV，调度算法在拼什么？
Why do automated container terminals use driverless cranes and AGVs, and what is the scheduling algorithm optimizing?
岸桥、堆场吊和自动导引车协同，靠算法在最短时间把船-堆场-卡车衔接好，减少设备空跑和拥堵。本质是在时空约束下求解大规模调度优化问题。
Quay cranes, yard cranes and AGVs coordinate so algorithms link ship-yard-truck in minimal time, cutting idle runs and jams. It is essentially large-scale scheduling optimization under space-time constraints.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
Steenken、Voss & Stahlbock，《集装箱码头运营与运筹学》（2004）
Steenken, Voss & Stahlbock, 'Container Terminal Operation and Operations Research' (2004)
#自动化码头 #AGV #调度优化
为什么汽油机的热效率很难突破45%？主要能量损失在哪里？
Why is it so hard for a gasoline engine to exceed about 45 percent thermal efficiency, and where does the lost energy go?
奥托循环的理论效率由压缩比决定，但压缩比受爆震限制，加上汽油机空燃比控制在化学计量附近、泵气损失和部分负荷时节气门节流损失大，实际效率远低于理论值。能量去向包括排气带走的热、冷却系统散失的热、摩擦与泵气损失以及不完全燃烧损失。提高效率的路线包括稀薄燃烧、高压缩比加米勒循环、直喷和可变压缩比等。
The theoretical efficiency of the Otto cycle is set by the compression ratio, but knock limits how high the ratio can go, and stoichiometric air-fuel control, pumping losses and throttle losses at partial load push real efficiency far below the ideal. Energy is lost to exhaust heat, coolant heat, friction and pumping, and incomplete combustion. Efficiency routes include lean burn, high compression with the Miller cycle, direct injection and variable compression ratio.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Heywood，《内燃机基础》
Heywood, 'Internal Combustion Engine Fundamentals'
独立核验依据 · Independent verification: 核验依据 1 ISBN 9781260116106 (2018)
#内燃机 #热效率 #奥托循环
磁悬浮列车为什么能"浮"起来跑，而且没有轮子？
Why can a maglev train float and run with no wheels?
磁悬浮利用电磁力对抗重力。常导型（EMS）靠车底电磁铁与轨道铁磁轨之间的吸引力把车体吸起来，悬浮间隙仅约1厘米，必须实时控制防止"吸死"；超导型（EDS）如日本L0列车，则用超导磁体在轨道线圈中感应出强大的排斥力，悬浮间隙更大且天然稳定。没有轮轨接触摩擦后，阻力只剩空气阻力，所以时速可达500公里以上，噪声和磨损也大幅下降。
Maglev uses electromagnetic force to beat gravity. Electromagnetic suspension (EMS) levitates by the attractive force between onboard magnets and ferromagnetic rails, holding a gap of only about 1 cm under real-time control to avoid contact. Superconducting EDS, as in Japan's L0, induces strong repulsion in track coils and floats with a larger, inherently stable gap. With no wheel-rail contact, the only drag left is air resistance, so speeds exceed 500 km/h with far less noise and wear.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《十万个为什么》第六版建筑与交通分册,少年儿童出版社,2013
Ten Thousand Whys: Architecture and Transportation volume, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#磁悬浮 #电磁力 #超导
电动汽车电池管理系统（BMS）的主要功能有哪些？为什么必须均衡管理？
What are the main functions of a battery management system (BMS) in an electric vehicle, and why is cell balancing necessary?
BMS负责采集每节电芯的电压、电流和温度，据此估算荷电状态（SOC）与健康状态（SOH），并在过充、过放、过温或过流时切断回路保护电池。由于制造差异和使用环境不同，电芯容量会逐渐离散，若不均衡，短板电芯会过早到达充放电边界而限制整个电池包，所以BMS通过被动或主动均衡使各电芯趋于一致，延长电池寿命。
A BMS measures per-cell voltage, current and temperature, estimates state of charge (SOC) and state of health (SOH), and disconnects the pack on overcharge, over-discharge, over-temperature or over-current. Because of manufacturing variance and uneven operating conditions, cell capacities drift apart over time; without balancing the weakest cell hits its charge or discharge limit early and limits the whole pack, so the BMS uses passive or active balancing to keep cells matched and extend battery life.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Linden & Reddy，《林登电池手册》（第4版）
Linden & Reddy, 'Lindens Handbook of Batteries' (4th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-07-037921-3 (1995, McGraw-Hill)
#电池管理 #BMS #电动汽车
为什么隧道里要装很强的通风系统？
Why do tunnels need strong ventilation?
隧道封闭空间里汽车尾气会积累一氧化碳等有害气体，且火灾时浓烟致命。通风系统持续把新鲜空气送进来、把污浊和烟气排出，保证能见度和人员逃生条件。
In an enclosed tunnel, vehicle exhaust builds up carbon monoxide and smoke is deadly in fire. Ventilation constantly supplies fresh air and exhausts pollutants and smoke, preserving visibility and escape conditions.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录仅给书名，无版次与年份；同一书名常对应多个版次，不臆测具体版本。
美国联邦公路管理局（FHWA），《公路隧道通风》
US FHWA, 'Highway Tunnel Ventilation'
#隧道 #通风 #安全
为什么高铁的轮子看起来是平的而不是像汽车一样有花纹？
Why do high-speed train wheels look flat rather than treaded like car tires?
高铁在钢轮钢轨上运行，靠轮缘和锥形踏面导向与自动对中，不需要橡胶轮胎那样的排水花纹。平整踏面保证高速时接触平稳、噪音低、磨损均匀。
Trains run on steel wheels and rails, guided by the flange and a slightly conical tread that self-centers, so no tread pattern is needed for drainage. A smooth tread gives stable high-speed contact, low noise, and even wear.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Iwnicki 编，《铁路车辆动力学手册》（2006）
Iwnicki, S. (ed.), 'Handbook of Railway Vehicle Dynamics' (2006)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-429-89062-8 (2nd ed., CRC Press, 2019)
#高铁 #钢轮 #踏面
为什么有时开车一路都是绿灯？交通信号是怎么"聪明"起来的？
Why do you sometimes hit green after green? How do traffic signals get smart?
那就是绿波带：工程师把主干道上相邻交叉口的绿灯启亮时间按设计车速错开，让车队以建议时速行驶时正好一路绿灯。更先进的信号控制还能根据路口埋设的检测线圈或视频识别出的车流量，实时调整各相位的绿灯时长，这叫感应控制或自适应控制，可用来优先放行公交车、疏导拥堵。配时还要兼顾行人过街时间与路口间距，绿波不是"永远绿灯"，而是把等待集中在少数路口。
That is a green wave: engineers offset the green-start times of adjacent intersections along an arterial by the travel time at a design speed, so a platoon rolling at that speed hits green after green. Smarter systems use detection loops or video to measure traffic and re-time phase durations in real time — actuated or adaptive control — which can also prioritize buses and dissolve congestion. Timing must respect pedestrian crossing times and intersection spacing; a green wave does not mean always green, just that delay concentrates at a few intersections.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
ITE，《交通工程手册》（第7版）
ITE, 'Traffic Engineering Handbook' (7th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787114026225（豆瓣书目条目: 交通工程手册）
#绿波带 #信号配时 #交通控制
为什么电动汽车普遍采用永磁同步电机作为驱动电机？
Why do electric vehicles predominantly use permanent-magnet synchronous motors (PMSM) as traction motors?
永磁同步电机的转子由永磁体提供磁场，无需从定子吸取励磁电流，因而效率更高、功率密度更大，同样的体积和重量能输出更强的扭矩，直接有助于增加续航里程。它体积小、低速扭矩大，配合磁场定向控制能实现精准的转速与扭矩调节。主要缺点是稀土永磁材料（如钕铁硼）价格波动大、高温下有退磁风险。
An EV traction PMSM generates rotor flux from permanent magnets, so it draws no excitation current from the stator and offers higher efficiency and power density, more torque for a given size and weight, which directly benefits driving range. It is compact, delivers strong low-speed torque, and pairs with field-oriented control for precise torque and speed regulation. Its main drawbacks are the cost volatility of rare-earth magnet materials such as NdFeB and the risk of demagnetisation at high temperature.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Mohan，《电力电子：变换器、应用与设计》（第3版）
Mohan, 'Power Electronics: Converters, Applications and Design' (3rd ed.)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL31566418W：Power Electronics Conv
#永磁同步电机 #驱动电机 #电动汽车
汽车悬架的软硬调节为什么要在舒适性和操控性之间权衡？
Why must suspension tuning trade off ride comfort against handling?
悬架通过弹簧和减振器吸收路面冲击，软悬架能把振动过滤得更彻底，乘坐舒适但转弯时车身侧倾大、动态响应慢。硬悬架支撑好、转向反应快，但路面冲击直接传到车身，舒适性下降。减振器阻尼也需要平衡：阻尼过小车身余振不断，阻尼过大则冲击刚性传递，可变阻尼悬架正是为了在不同工况下动态切换这种权衡。
Suspension uses springs and dampers to absorb road impacts: soft springs filter vibration thoroughly for comfort but allow large body roll and slow responses in corners, while stiff springs support the body and give quick steering response at the cost of transmitting road shocks. Damper tuning is a similar balance, too little damping leaves the body oscillating and too much makes impacts feel harsh. Adaptive dampers exist precisely to shift this trade-off dynamically with driving conditions.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
SAE International 汽车工程手册（Bosch《汽车手册》）；AASHTO《公路与城市道路几何设计》
SAE International; Bosch, Automotive Handbook; AASHTO, A Policy on Geometric Design of Highways and Streets
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL3202243W：A policy on geometric d
#悬架 #减振器 #操纵稳定性
自动驾驶汽车是如何"看见"周围世界的？
How does a self-driving car "see" the world around it?
自动驾驶融合多种传感器：激光雷达发射激光束测距，得到三维点云；毫米波雷达利用多普勒效应在雨雾中测目标的距离与速度；摄像头提供车道线、交通标识、信号灯等语义信息。各路数据先经过时间同步和空间标定对齐，再交给感知算法做目标检测与跟踪。多传感器冗余是关键：摄像头怕逆光黑夜，毫米波雷达分辨不出低矮障碍，彼此互补才能在各种天气下可靠感知。
Self-driving cars fuse multiple sensors: lidar fires laser pulses to build 3-D point clouds, millimeter-wave radar uses the Doppler effect to measure distance and speed through rain and fog, and cameras supply semantic details like lane lines, signs, and traffic lights. The data streams are synchronized in time and aligned in space through calibration, then fed to perception algorithms for detection and tracking. Redundancy is key: cameras struggle in glare and darkness, radar misses low obstacles, so the sensors cover each other's weaknesses.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Maurer、Gerdes、Lenz & Winner，《自动驾驶：技术、法律与社会视角》（Springer, 2016）
Maurer, Gerdes, Lenz & Winner, 'Autonomous Driving: Technical, Legal and Social Aspects' (Springer, 2016)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-3-662-45854-9 / DOI 10.1007/978-3-662-45854-9 (
#自动驾驶 #传感器融合 #激光雷达
什么是智能交通系统 ITS，它如何用传感器缓解拥堵？
What is ITS and how do sensors ease congestion?
智能交通系统把摄像头、地感线圈和雷达等传感器连到控制中心，实时统计车流量并动态调整信号灯配时、发布诱导信息。通过均衡路网负荷和减少空等，整体通行效率提升、拥堵缓解。
Intelligent Transport Systems link cameras, loop detectors, and radar to a control center that counts traffic in real time and adjusts signal timing and guidance. Balancing network load and cutting idle waits raises throughput and eases jams.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录仅给书名，无版次与年份；同一书名常对应多个版次，不臆测具体版本。
美国交通部（USDOT），《智能交通系统战略计划》
USDOT, 'Intelligent Transportation Systems (ITS) Strategic Plan'
#智能交通 #传感器 #信号
激光雷达和毫米波雷达在车载感知上各有什么优劣？
What are the strengths and weaknesses of automotive LiDAR versus millimetre-wave radar?
激光雷达通过发射激光脉冲测距并扫描得到高分辨率三维点云，能精确识别物体轮廓和位置，但成本高、在雨雪雾天气性能衰减明显。毫米波雷达直接测量距离和速度（利用多普勒效应），对雨雾穿透力强、测速准、成本低，但角度分辨率低，难以分辨行人等小目标。因此两者常与摄像头互补使用，各取所长。
LiDAR emits laser pulses and scans to build high-resolution 3D point clouds, accurately resolving object shapes and positions, but it is expensive and degrades badly in rain, snow and fog. Millimetre-wave radar directly measures range and velocity via the Doppler effect, penetrates rain and fog well, is accurate for speed and cheap, but offers low angular resolution and struggles to distinguish small objects such as pedestrians. The two are therefore usually fused with cameras so each covers the others' weaknesses.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Maurer、Gerdes、Lenz & Winner，《自动驾驶：技术、法律与社会视角》（Springer, 2016）
Maurer, Gerdes, Lenz & Winner, 'Autonomous Driving: Technical, Legal and Social Aspects' (Springer, 2016)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-3-662-45854-9 / DOI 10.1007/978-3-662-45854-9 (
#激光雷达 #毫米波雷达 #自动驾驶
为什么电动汽车需要电池热管理系统？它如何保证电池在低温下也能正常工作？
Why do electric vehicles need a battery thermal management system, and how does it keep the battery working in cold weather?
锂离子电池的最佳工作温度通常在20至40摄氏度，高温会加速老化甚至引发热失控，低温则使内阻增大、可用容量和充电功率大幅下降。热管理系统通过液冷或风冷回路、加热膜或热泵实现加热与冷却：高温时把热量带出电池包，低温时先加热再允许大电流充电，使电池始终处于适宜温度区间，既保障安全也维持性能。
Lithium-ion batteries work best around 20 to 40 degrees Celsius: heat accelerates ageing and can trigger thermal runaway, while cold raises internal resistance and sharply cuts usable capacity and charge power. The thermal management system heats and cools through liquid or air loops, heating pads or heat pumps: it rejects heat from the pack in summer, and preheats before fast charging in winter, keeping cells in the optimal window for both safety and performance.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Linden & Reddy，《林登电池手册》（第4版）
Linden & Reddy, 'Lindens Handbook of Batteries' (4th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-07-037921-3 (1995, McGraw-Hill)
#电池热管理 #热失控 #电动汽车
为什么高铁过隧道时耳朵会闷，隧道口设计成“喇叭形”或设缓冲结构有什么用？
Why do ears pop on a high-speed train entering a tunnel, and what do flared tunnel mouths or buffer structures do?
列车高速挤入隧道会把空气猛推向前，形成压缩波在洞内来回反射，气压突变压迫耳膜。洞口渐扩或设开孔缓冲结构能放缓压力变化，减轻不适和微压波噪声。
A fast train shoves air ahead, forming compression waves that reflect in the tunnel and suddenly change pressure on your ears. A flared mouth or perforated buffer eases that pressure change, reducing discomfort and micro-pressure-wave noise.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录仅给书名，无版次与年份；同一书名常对应多个版次，不臆测具体版本。
美国联邦公路管理局（FHWA），《公路隧道通风》
US FHWA, 'Highway Tunnel Ventilation'
#高铁隧道 #压缩波 #微压波
天空中那么多飞机，为什么不会相撞？
With so many planes in the sky, why do they never collide?
民航客机大多在仪表飞行规则下由空中交通管制（ATC）统一指挥。飞机沿指定的航路飞行，航路在水平方向和垂直方向都互相隔开（垂直间隔通常约300米，雷达管制下还可缩小），管制员用雷达监视并下达指令保证间隔。飞机还装有应答机广播自己的高度和呼号，机载防撞系统（TCAS）在间隔过小时会自动给出爬升或下降指令。起飞降落阶段则由塔台按顺序和间隔放行，跑道时刻精确到秒级。
Commercial flights mostly fly under instrument flight rules controlled by air traffic control (ATC). Aircraft follow defined airways that are separated both laterally and vertically — vertical separation is typically about 300 m, reduced under radar control — and controllers monitor radar and issue instructions to keep spacing. Aircraft also broadcast their altitude and identity via transponders, and the TCAS collision-avoidance system automatically commands climb or descend when separation gets too tight. At takeoff and landing, tower controllers sequence departures and arrivals to intervals timed in seconds.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Anderson《空气动力学基础》；ICAO 巡航高度层
Anderson, Fundamentals of Aerodynamics; ICAO cruising levels
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787516504413（豆瓣书目条目: 空气动力学基础）；本条出处含多部著作，此标识只担保上面点名
#航空管制 #飞行间隔 #TCAS
为什么高铁车轮不是平的，而是带一点"锥度"？
Why are train wheels slightly cone-shaped instead of flat?
车轮踏面做成锥形是为了让列车自动对中转弯。轮对是左右两轮固定在一根轴上的，过弯时外轮走的长轨、内轮走短轨，若两轮滚动半径相同就会打滑。锥形踏面让车体在弯道向一侧偏移时，外侧车轮的滚动半径变大、内侧变小，两轮转速自动匹配内外轨长度，实现自导向。这个几何特性也正是高铁"蛇行运动"的来源，需要靠踏面磨耗管理和主动稳定来控制。
Conical wheel treads let a trainset self-center on curves. A wheelset has two wheels fixed on one axle; in a curve the outer wheel travels a longer rail than the inner, and equal rolling radii would cause slipping. With a coned profile, when the set shifts sideways the outer wheel rides a larger rolling radius and the inner a smaller one, so the wheels automatically match the two rail lengths and steer themselves. The same geometry is what produces high-speed "hunting" oscillation, controlled through tread wear management and active stability.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Iwnicki 主编,《Handbook of Railway Vehicle Dynamics》第2版,CRC Press,2019
S. Iwnicki ed., Handbook of Railway Vehicle Dynamics, 2nd ed., CRC Press, 2019
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-429-89062-8 (2nd ed., CRC Press, 2019)
#高铁 #轮轨 #锥形踏面
红绿灯是怎么知道该变红的？
How does a traffic light know when to turn red?
红绿灯里有定时器或埋在路下的传感器，数着每边等了多少车和等多久。轮到别的方向时，控制器就让它变红、让另一方向变绿，大家轮流走。
Traffic lights use timers or sensors buried in the road that count cars and wait time. When it's another direction's turn, the controller turns this one red and the other green, so everyone takes turns.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
ITE，《交通工程手册》（第7版）
ITE, 'Traffic Engineering Handbook' (7th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787114026225（豆瓣书目条目: 交通工程手册）
#红绿灯 #信号 #控制
为什么有些大船后面拖着一长串小艇或小船，像火车一样排成一列走？
Why do some big ships drag a long train of smaller boats in a line like a train?
那是顶推或拖带船队，把多艘驳船串起来由一艘拖轮带着走，比各自分开更省油、更好指挥。就像公路上的列车，一次运一大串货物。
That is a towed or pushed barge train, linking several barges behind one tug to move them together—more fuel-efficient and easier to command than separate trips. Like a train on water hauling a long string of cargo at once.
难度 入门 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Tupper，《船舶原理导论》（第5版）
Tupper, 'Introduction to Naval Architecture' (5th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780080982373 (2013)
#船队 #拖带 #驳船
为什么高速公路的弯道要向外倾斜？
Why are highway curves banked outward?
弯道路面倾斜后，车辆转弯时路面的支撑力有一部分指向圆心，帮忙提供转弯所需的向心力，减少靠轮胎摩擦力硬扛，于是过弯更稳、更不容易侧滑。
Banking tilts the road so part of the normal force points toward the center, helping supply the centripetal force for turning and reducing reliance on tire friction, making cornering steadier and less prone to sliding.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
ITE，《交通工程手册》（第7版）
ITE, 'Traffic Engineering Handbook' (7th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787114026225（豆瓣书目条目: 交通工程手册）
#弯道 #倾斜 #向心力