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# 基金

2020 年，自己的投资风格基本成型，“主题定投，波段赎回”；在市场大环境不错的情况下，收益可观。以支付宝为例，2020 年的盈利大概是 30%，超过了大多数股市投资者，但是自己盘子小，总体收益也只有一万多元。

2020 年前，自己喜欢在支*宝上，购买平台推荐的基金，往往是这只基金买 10 块，那只基金每周定投 10 块钱等等小额操作，基金投资特别零散。这些零散小额基金就像杂音一样，浪费了自己的精力，自己不清楚自己的投资分布是什么，布局重点是什么，赚钱收益怎么样。

# 好的习惯

### 出售闲置下来的物品

• 把二手书店搬到网上的多抓鱼
• 当你想卖掉家里囤积的旧书，只需要打开「多抓鱼」，扫描 ISBN 码后，等待顺丰快递员上门收书即可，经过多抓鱼经过审核后，你就能得到卖书钱了。

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# shell 和 终端 的概念区别

• 终端termimal，作用是提供一个命令的输入输出环境，在 linux 下使用组合键 ctrl+alt+T 打开的就是终端。
• shell 是一个命令行解释器，是 linux 内核的一个外壳，负责外界与 linux 内核的交互。shell 接收用户或者其他应用程序的命令，然后将这些命令转化成内核能理解的语言并传给内核，内核执行命令完成后将结果返回给用户或者应用程序。

# 终端命令行快捷键

• ctrl + a 回到命令行的行首
• ctrl + e 回到命令行的行尾
• ctrl + c 取消当前行输入的命令，并重新到下一行
• ctrl + r 出现命令历史记录搜索提示，输入字符后会自动匹配命令
• ctrl + b 向后退一个字符，相当于向左方向键
• ctrl + f 向前进一个字符，相当于向右方向键
• ctrl + p 向上翻以前的输入命令，相当于向上方向键
• ctrl + n 向下翻以前的输入命令，相当于向下方向键
• alt + b 向后跳一个字
• alt + f 向前进一个字
• ctrl + w 从光标位置向后删除一个字
• ctrl + y 粘贴最后一个删除的字
• ctrl + d 删除当前光标位置的一个字符
• ctrl + u 从光标当前位置删除所有字符至行首
• ctrl + k 从光标当前位置删除所有字符至行尾，相当于长按ctrl + d

## tar 文件解压缩

• The tar command allows you to create and extract tar archives. The tar command auto-detects compression type and extracts the archive.
• Bzip2 is one of the most popular algorithms for compressing tar files. By convention, the name of a tar archive compressed with bzip2 ends with either .tar.bz2 or .tbz2.

### 参考资料

• https://linuxize.com/post/how-to-extract-unzip-tar-bz2-file/

# Reference

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2020 年 10 月 末，自动驾驶领域的领跑者 -- Waymo，在其 官网 首次公开披露了其在凤凰城运营自动驾驶汽车的里程和碰撞数据，本文基于这份报告，提炼一些观点和数据。

1. 倒车碰撞
2. 侧擦碰撞
3. 正面碰撞
4. 或对方逆行、追尾碰撞
5. 在十字路口或拐角处的碰撞等等。

# 专业名词介绍

• automated vehicles (AVs)
• automated driving system (ADS)
• operational design domain (ODD)

# Abstract

• 这份报告总结了 Waymo 在凤凰城 (Phoenix) 测试区域的 610 万英里的自动驾驶测试数据，包括有车上安全员监管 ( trained operator behind the steering wheel) 的自动驾驶，和 65000 英里的没有安全驾驶员无人驾驶 (driverless operation)。 > The data presented in this paper represents more than 6.1 million miles of automated driving in the Phoenix, Arizona metropolitan area, including operations with a trained operator behind the steering wheel from calendar year 2019 and 65,000 miles of driverless operation without a human behind the steering wheel from 2019 and the first nine months of 2020.

• 报告中承认，这段测试期间 Waymo 自动驾驶汽车卷入了 18 起真实的碰撞事故和 29 次仿真事故(被安全驾驶员及时接管，但是在模拟器中发生碰撞事故)，所幸均没有造成致命伤害。 > There were 47 contact events that occurred over this time period, consisting of 18 actual and 29 simulated contact events, none of which would be expected to result in severe or life-threatening injuries

• Waymo 表示，绝大多数事故都和人类驾驶员的不守规则和其他错误相关；由其他司机不谨慎行为诱发的事故频率清楚地提醒人们，只要自动驾驶汽车与人类司机共享道路，避免碰撞就是一大挑战。 > Nearly all the events involved one or more road rule violations or other errors by a human driver or road user. > The presence of collisions that resulted from challenging situations induced by other drivers serves as a reminder of the limits of AV collision avoidance as long as AVs share roadways with human drivers.

• 在 Waymo 看来，报告不只是向公众公开测试里程和事故，更是做了一个向公众分享自动驾驶行驶安全的一个例子。 > The long-term contributions of this paper are not only the events and mileages shared, but the example set by publicly sharing this type of safety information.

# Introduction

• 报告的目的是公开更多数据，来尽力提高公众对自动驾驶车辆的信心和接受程度 (acceptance)。 > The purpose of this paper is to make available relevant data to promote awareness and discussions that ultimately foster greater public confidence in AVs.

## Public Road Testing

• 在测试初期，为了保证 AVs 在公开道路测试时的安全和行为合理，会有经过培训的驾驶员坐在驾驶员的位置，随时准备接管车辆。 > In order to perform initial public road testing of AVs in a safe and responsible manner, trained vehicle operators are seated in the driver’s seat and can take over the driving task at any time.

## The Role of Counterfactual (“What If”) Simulation

Waymo 统计了经过培训的安全驾驶员控制车辆以避免碰撞的事件，然后工程师们会模拟如果驾驶员没有接管车辆自动驾驶系统的话会发生什么，从而产生一个反事实或 “假设” 出来的推断情景。他们利用这些事件来不断检验调整汽车的临场决策反应，然后利用这些数据改进其自动驾驶软件。

• 反现实的仿真用来预测自车在接管后的一段时间内的表现，给我们提供如果安全员没有接管，那么自车会发生什么的视角。 > Counterfactual disengagement simulation is used to represent the predicted vehicle response for a brief period (seconds) after disengagement, and the simulation outcome provides insight into what could have happened had the trained operator not intervened. > MC: 只能提供极短时间的仿真，否则容易和真实世界背离。另外，需要有精细的模型，可以预期如果没有接管发生，交通参与者的行为。

• 反事实的接管仿真可以独立使用 (individually) 也可以聚合使用 (in aggregate)。 > The outcomes of counterfactual disengagement simulations are used both individually and in aggregate.

• 独立仿真时间：场景库的虚拟仿真，可以作为评估软件开发的测试集。 > Individual counterfactual disengagement simulation: If the simulation outcome reveals an opportunity to improve the behavior of the ADS, then the simulation is used to develop and test changes to software algorithms. The disengagement event is also added to a library of scenarios, so that future software can be tested against the scenario. > 在细分领域，自动驾驶的策略会随着接管场景而发生调整和变化，容易造成回滚，而这些场景集合可以作为软件的回滚测试的一部分。
• 聚合使用：评估 AVs 的路测表现。 > At an aggregate level, Waymo uses results from counterfactual disengagement simulations to produce metrics relevant to the AV’s on-road performance.
• 软件进化带来的仿真不可复现性问题 > Waymo’s models will continue to evolve, and even for these brief simulations, future models may result in different simulated outcomes.

## Aims and Contributions of this Paper

• 报告包括在 610 万英里测试中的事故总计和事故描述 (包括真实的事故和实际接管但发生仿真事故)。这部分里程，相当于美国普通持证司机 500 多年的驾驶里程。 > This paper includes safety data in the form of event counts and event descriptions from over 6.1 million miles of driving conducted in the Waymo Driver’s driverless ODD. This mileage figure represents over 500 years of driving for the average U.S. licensed driver.

• 本文提供了两种信息：一种是在或无安全驾驶员情况下的真实碰撞（actual contact event）；一种是驾驶员接管，但是在后续的仿真中发生碰撞的，但是因为安全员接管实际没有发生碰撞。 > For these miles, this paper provides information regarding

1. every actual contact event that vehicles were involved in during driverless operation with and without trained operators, as well as
2. events in which the vehicle’s trained operator disengaged and subsequent counterfactual simulation resulted in any contact between the AV and the other agent, had the disengagement not occurred

# Methods

## Data sources

• Waymo 自动驾驶软件的最高速度是 45 英里每小时，换算成公里数是 72.4km/h。除了大雨和沙尘暴天气，会在白天和夜间进行无人驾驶测试。 > The ODD includes roadways with speed limits up to and including 45 miles per hour. Driverless operations occur at all times day and night, except during inclement weather including heavy rain and dust storms.

> MC: 这种模式下，在 2019 年初到 2020 年九月底的测试里程是 6.5 万英里。

• 由驾驶员的自动驾驶（Self-driving with trained operators）：虽然由自动驾驶系统控制车辆，但是车上有安全驾驶员可以随时接管车辆。 > Self-driving with trained operators , in which the automated driving system controls the vehicle but there is a trained vehicle operator in the driver’s seat who can disengage and take over the driving task.
> MC: 这种模式下，2019 年全年的测试里程是 6.1 百万里程。提供一整年的测试数据，可以控制和规避潜在的季节影响 (controlling for potential seasonality effects)。在评估自车表现时，不能忽略季节影响，比如秋天有落叶误感，方向盘急打要比冬季严重。

## Data from Actual Collisions and Minor Contacts

• 数据包括自动驾驶 (self-driving with trained operators mode) 或无人驾驶 (driverless mode) 模式下每一个真实碰撞 (actual collision) 和小事故 (minor contact event)，甚至包括行人撞上静止自车的事故。 > This definition encompasses not only every severity of collision, but also events such as a pedestrian walking into the side of the stationary AV.

## Data from Counterfactual (“What If”) Simulation

### Simulation of the AV motion post-disengagement

• 接管后的仿真 (post-disengage simulation) 第一步，就是仿真自车的表现 (AV’s counterfactual post-disengage motion)。这样的仿真比较简单，容易快速实现。 > The first step in post-disengage simulation is therefore to simulate the AV’s counterfactual post-disengage motion. > This is performed by providing a simulation running Waymo self-driving software with the AV’s pre-disengage position, attitude, velocity, and acceleration along with the AV’s recorded sensor observations and simulating the response of the software and resulting motion of the Waymo vehicle.
• 检测是否和其他交通参与者有碰撞，重叠的位置 (overlapping positions) 意味着有潜在的碰撞 (potential collision)。 > Overlapping positions indicate a potential collision. After the AV’s post-disengage motion is simulated, a check is performed to determine if the simulated positions of the AV overlap at any point with the recorded positions of other agents.

• 仿真第二步：在接管和仿真两种情况下，自车的行为存在不一致 (比如位置和速度不一样)，那么就会影响其他参与者的行为，所以做仿真时，参与者的行为可能和实际不符，需要为其他交通参与者重新建模 (modeling the behavior of other agents)。这是比较困难的，需要有比较丰富的模型和交互设计。 > This may not be realistic in cases where the other agents would likely have responded differently to the AV’s counterfactual simulated motion than they did to the AV’s actual post-disengage motion. In such cases, further simulation is required.

• 总结一下，接管后的仿真，不仅需要使用恰当的软件，仿真自车的行为，也需要仿真其他交通参与者的行为，而这是比较困难的。

### Modeling of other agents

• 为其他交通参与者长时间建模是比较有挑战性的，但是在接管后的短时间内建立冲突避免 (conflict-avoidance) 或避障行为 (collision-avoidance) 是可行的做法。 > While modeling agent behavior over long periods of time is challenging, understanding plausible conflict-avoidance or collision-avoidance behavior over the short time horizon following a disengagement is a more feasible task.

• Waymo 使用人类避障行为模型 (human collision avoidance behavior models) 来反映短期内障碍物的表现；可以使用离散的多因素(反应时间、刹车和打方向盘的力度)来反映交通参与者可行的反应空间 (the space of plausible reactions)。 > Waymo expresses short-term agent responses using human collision avoidance behavior models. > These models aim to capture the responses of human drivers, motorcyclists, cyclists, and pedestrians to collision avoidance situations, such as braking by a lead vehicle or being cut-off by another agent who fails to yield right-of-way. > Because only the agent’s short-term response needs to be modeled, the space of plausible reactions to such stimuli can be defined using a discrete set of factors such as response times to specific inputs and brake or swerve ability.

• 因为上述的多因素因环境因人而异(比如反应时间)，Waymo 在开发和评估 AV 行为时，使用一个范围来表示可能的人类驾驶表现 (a broad spectrum of potential human driving performance). 为了透明度和简单性，本文使用确定的模型 (deterministic model) 来对一个给定的输入产生给定的输出。 > Waymo considers a broad spectrum of potential human driving performance in developing and evaluating the AV, but for transparency and simplicity, the results reported in this paper are based on deterministic models that generate a single response to a given input.
> Other methods can be used to capture a range of possible human responses, such as probabilistic counterfactual outcomes, but they are more complex.

• Waymo 独有的人类避碰模型是基于现在已有的道路使用者的行为模型 (road user behavior modelling frameworks)，并基于人类自然的避碰模型 (naturalistic human collision) 和差点碰撞的数据 (near-collision) 来校正。 > Waymo’s proprietary human collsion avoidance behavior models are based on existing road user behavior modelling frameworks and calibrated using naturalistic human collision and near-collision data.

• 交通参与者的反应被其刹车和转向性能所限制。Waymo 针对不同类型的交通参与者以及不同的触发场景 (different stimuli)，使用不同的模型。 > The agent’s response is further constrained by human braking and steering limitations. Waymo uses different models for different types of agents, including heavy trucks, pedestrians, and cyclists, and for different stimuli such as a forward agent braking or an agent emerging from behind an occlusion.
> MC: 如果单车智能比较高，贴近于人类驾驶员的表现，那么是否可以使用自动驾驶软件的算法模拟车辆的行为；也就是说其他车和自车的表现拟合度比较高，能否使用自车模型来仿真其他车的表现呢？

• 人类避碰模型的使用场合和条件：当仿真接管后的 AV 轨迹和交通参与者的实际轨迹有重叠，那么就会在接管后的仿真中使用人类避障模型 (human collision avoidance behavior models)。 > Human collision avoidance behavior models are employed for disengagements in which there is overlap between the simulated post-disengage trajectory of the AV and the actual post-disengage trajectory of another agent.
> In these cases, instead of using the agent’s recorded post-disengage trajectory, the post-disengage trajectory of the other agent is determined by applying the relevant human collision avoidance behavior model.

### Contact analysis of simulated collisions

• Waymo 仿真分析表明，接管很少会造成实际上的碰撞(大部分是防御性接管)。事实上，超过 99% 的接管没有仿真的接触 (simulated contact) 发生。 > Our simulation analysis indicates that disengagements would rarely result in contact. In fact, in more than 99.9% of disengagements, no simulated contact is found to occur.
> MC: 因为 Waymo 的软件开发程度比较高，才可以有这样的把握；对于初创期的软件，没有充分的道路测试，切不可使用这样的结论。

Waymo 根据伤害可能性、碰撞物体、撞击速度和撞击几何结构分析，以确定某些事故的严重性，。

• 如何碰撞发生，那么如何确定碰撞的严重程度 (event severity) 呢？Waymo 根据碰撞障碍物的类型 (collision object)，相对速度 (impact velocity) 和碰撞位置 (impact geometry) 来确定可能的伤害程度 (likelihood of injury)。Waymo 使用国家碰撞数据库 (national crash databases) 来为事故严重程度分级 (event severity category)，事件的统计等级分为预计无伤害 (S0) 到可能的严重伤害 (S1、S2 和 S3)。 > This determination categorizes collisions based on likelihood of injury and is based on the collision object (e.g., other vehicles, static objects, or vulnerable road users such as pedestrians or cyclists), impact velocity, and impact geometry.
> Waymo’s methods for determining event severity category are developed using national crash databases and are periodically refined to reflect updated data.

# Results: Collisions and Minor Contacts

> columns categorized by estimated event severity using the ISO 26262 severity classes: S0, S1, S2, and S3, ranging from no injury expected (S0) to possible critical injuries expected (S3). * MC: 虽然中美两国的交通法规和驾驶习惯不同，但是这样的交通事故分类是可以拿来参考的。

Waymo 报告中的碰撞事故中，没有 S2 或 S3 级别事故发生，最严重的事故是 S1 级别 (airbag-deployment-level)，有 3 次保护气囊弹出。 > There were no actual or predicted S2 or S3 events. One actual event involved deployment of another vehicle’s frontal airbags and the Waymo vehicle’s side airbags.

Waymo 通过和人类的事故相比较，来表明其自动驾驶软件在减少人员伤亡上的可能性。 > Comparison between these human collision statistics and Waymo event counts provides insight into the Waymo Driver’s opportunity for reducing injuries and fatalities due to collisions.

• In total, the Waymo vehicle was involved in 20 events involving contact with another object and experienced 27 disengagements that resulted in contact in post-disengagement simulation, for a total of 47 events (actual and simulated).
• 我的困惑点：上述表格中统计的实际碰撞是 18 次，仿真碰撞是 29 次，这和 Waymo 的文字描述是不统一的 (实际碰撞 20 次，虚拟碰撞 27 次)；那么是有数据修正吗，还是我粗心搞错了呢？

## Single Vehicle Events

Waymo 自动驾驶车辆没有发生偏离车道 (road departure) 和撞上行人的单车事故 (struck a pedestrian or cyclist)；而这类事故在人类驾驶数据中占比约为 60%。 > The Waymo Driver did not have any events (actual or simulated) in this data that involved road departure, contact with the roadway environment/infrastructure or other fixed objects, or rollover. There were also no collisions (actual or simulated) in which the Waymo Driver struck a pedestrian or cyclist.

Waymo 在减速或者静止时，被行人或滑板车从右侧撞上。 > In each instance, the Waymo Driver decelerated and stopped, and a pedestrian or cyclist made contact with the right side of the stationary Waymo vehicle while the pedestrian or cyclist was traveling at low speeds. * MC：我怀疑自车突然急刹，行人来不及反应而撞上去。

## Multiple Vehicle Events: Reversing Reversing

In both scenarios, the Waymo vehicle was stopped or traveling forward at low speed and the other vehicle was reversing at a speed of less than 3 mph at the moment of contact to the side of the Waymo vehicle.

## Multiple Vehicle Events: Same Direction Sideswipe

> The Waymo Driver was involved in ten simulated same direction sideswipe collisions.

### Other vehicle changing lanes, Waymo vehicle straight

The other vehicle changed lanes into the area occupied by the Waymo vehicle, which resulted in simulated or actual sideswipe collisions.

### Other vehicle straight, Waymo vehicle changing lanes

In both of these simulations, the Waymo Driver made a lateral movement in front of a vehicle traveling straight in an adjacent lane.

## Multiple Vehicle Events: Rear End

> The Waymo Driver was involved in fourteen actual and two simulated rear end collisions

### Rear end struck event group, Waymo vehicle moving slower while traveling straight

In the other collision, the Waymo vehicle, traveling straight at the speed limit, was struck by a vehicle traveling 23 (57-35) mph over the posted speed limit.

### Rear end struck event group in right turning maneuvers

These collisions occurred while the Waymo was stationary or near stationary waiting for crossing traffic to clear after having gradually slowed to account for this traffic.

### Rear end struck event with braking of lead vehicle during left turn

• 自车在路口左转急刹停 (a deceleration to a near stop)，后面车辆跟车距离不够来不及刹车。 > The remaining rear end struck collision involved a deceleration to a near stop by the Waymo Driver while making a left turn in an intersection with a following vehicle that was traveling at a speed and following distance that did not allow for the following driver to successfully respond to the Waymo Driver’s braking.

## Multiple Vehicle Events: Angled

Angled collisions, those that are typically seen at intersections and involve crossing or turning vehicles, account for approximately one quarter of all human-driven collisions and a similar fraction of the contribution to all human-driven fatalities.

### Angled event group with the other vehicle not yielding to Waymo right-of-way

The collisions in this grouping (ten simulated, one actual) involve the Waymo vehicle traveling straight in a designated lane at or below the speed limit. In all scenarios, the turning/crossing other vehicle either disregarded traffic controls or otherwise did not properly yield right-of-way.

In both instances, when the simulated Waymo Driver became aware of the other vehicle's intention to enter the travel lane, the simulated Waymo Driver initiated braking in an attempt to avoid/mitigate impact. * 如果检查到其他车不让行，那么 Waymo 自车会开始刹车来避免碰撞。

## Angled event group with Waymo vehicle crossing another vehicle’s path

The collisions in this grouping involve four simulated collisions, where the Waymo Driver was making a right turn from a rightmost lane that was either splitting to an additional lane, or had been the result of two lanes merging to one.

Waymo 向右变道时和右侧车道的直行车辆发生碰撞，类似于国内的自车右转，与自行车道的交互。 > In each event, a passenger vehicle attempted to pass the Waymo vehicle on the right while the Waymo Driver was slowing to make the right turn with the right turn signal activated.

# Discussion

Of the fifteen angled events, eleven events were characterized by the other vehicle failing to properly yield right-of-way to the Waymo vehicle traveling straight at or below the speed limit. > MC: 针对自车有路权，其他车辆不让行的情况，Waymo 也依赖安全驾驶员及时接管。

• 人类驾驶行为的不稳定性和不安全性，导致了绝大多数的碰撞。几乎所有的事故都是因为其他交通参与者违背交通规则或者交通表现有偏差。 > Humans exhibit a large variation of driving behaviors including deviations from traffic rules and safe driving performance that can lead to collisions.
> Nearly all events summarized above involved one or more road rule violations or other driving performance deviations by another road user.

• Waymo 在努力实现不因为自身原因造成碰撞的同时，也尽量减少因为人类走神 (inattention)，激进驾驶 (aggressive driving) 和超速 (speeding) 带来的可能碰撞。 > In addition to Waymo's key focus on not causing collisions, Waymo also works to mitigate possible collisions due to human behaviors such as inattention, aggressive driving, and speeding.

• Although many of these situations would not be present in a future with a high proportion of AVs, we envision sharing roads with human drivers for the foreseeable future. The rare contact events described in this paper are used to develop enhanced collision avoidance to improve traffic safety, and we will continue to focus on enhancing avoidance of human-induced collisions. > 这些场景在道路上不常见，但是也无法避免，自动驾驶同行可以反思遇到的这些 corner cases.

• Waymo 在努力减少事故发生的可能性 (likelihood)，而不仅仅是避免碰撞。自车的行为，要能够被其他交通参与者 (other road users) 可判断 (interpretable) 和可预测 (predictable)。 > Beyond collision avoidance, Waymo also continually investigates improvements to the Waymo Driver’s behaviors to reduce the likelihood of conflict with human-driven vehicles and other road users.
> This illustrates a key challenge faced by AVs operating in a predominantly human traffic system and underscores the importance of driving in a way that is interpretable and predictable by other road users.

• 相比于人类，Waymo 的自动驾驶能力是可以不断提升的，适用到整个车队上。 > Unlike human drivers, who primarily improve through individual experience, the learnings from an event experienced by a single AV can be used to permanently improve the safety performance of an entire fleet of AVs.

## Aggregate Safety Performance

Waymo 车辆在单车表现 (single-vehicle collision typology) 和 追尾问题 (rear-end collisions) 上的良好表现，已经优于人类。 > The Waymo Driver experienced zero actual or simulated events in the “road departure, fixed object, rollover” single-vehicle collision typology, reflecting the system's ability to navigate the ODD in a highly reliable manner.
> In addition, while rear-end collisions are one of the most common collision modes for human drivers, the Waymo Driver only recorded a single front-to-rear striking collision (simulated) and this event involved an agent cutting in and immediately braking without allowing for adequate separation distance (consistent with antagonistic motive).

### Lower-severity collision risk

> When comparing driving data, the mileage needed to reveal statistically significant differences also depends on the magnitude of the differences in the actual rates being compared.

For a given metric, the larger the difference in performance, the fewer miles that are required to establish statistical confidence in a hypothesis of non-inferiority or superiority.

### Higher-severity collision risk

> MC：目前的测试里程，可以为 Lower-severity 提供支持，但是不能为偶发的 Higher-severity 提供支持，里面有统计噪声 (statistical noise)。
> At this mileage scale, the statistical noise is extremely large and zero or low event counts only provide performance bounds, which necessitates the consideration of other metrics to fully assess the safety of the Waymo Driver.

1. 通过仿真和封闭场测试来评估高风险的表现. > Waymo uses other methods to evaluate the higher-severity performance, including both simulation-based and closed-course scenario-based collision-avoidance testing.

2. 从低风险事故中发掘高风险事故的信息。 > Low-severity data, when evaluated in the context of each event’s collision geometry, may be informative of high-severity risk.

### Comparison benchmarks

Human driver collision rates have been widely discussed as providing a benchmark for AVs.

Obtaining reliable event counts that include such minor events typically requires analysis of naturalistic driving data.

## Limitations and Future Work

Limitations related to the statistical power of the mileages reported have been discussed in the above section on aggregate collision frequencies. > 即，目前的测试里程，可以为 Lower-severity 提供支持，但是不能为偶发的 Higher-severity 提供支持，里面有统计噪声 (statistical noise)。

### Limitations of counterfactual simulations

• 反事实仿真只是预测，但不是绝对的准确。 > Due to the nature of human agent behavior, disengagement simulations are not definitive: counterfactual simulations predict what could have occurred, but cannot definitively predict exactly what would have occurred.
> As a result, had the driver not disengaged, some of the reported simulated collisions may not have actually occurred (e.g. other agents may have behaved differently). Conversely, other events that, in simulation did not result in contact, may have actually resulted in collisions (e.g. if the other agent had been distracted at the critical moment).

• Waymo therefore takes a cautious approach to interpreting both the outcomes of individual collisions and aggregate performance metrics, and considers them in the context of other indicators of AV performance.

### Secondary collision in simulated events

The severities ascribed to the simulated collisions are based on the single impact depicted in the simulation. Owing to complexities in accurately modeling post-impact vehicle dynamics (which may or may not involve subsequent steering and braking maneuvers from the other vehicle), the outcome of any secondary collisions that might occur subsequent to the simulated event are not explicitly modeled.

Waymo 的第一次碰撞，可以包含绝大多数的严重事故，二级事故不是很重要；二次碰撞需求显得不是那么紧迫。 > In Waymo’s ODD, the vast majority of primary vehicle-to-vehicle collisions (99% for all collisions, 95% for fatal collisions) included in police-reported crash databases involve either a single vehicle-to-vehicle collision event or a subsequent collision event of equal or lesser severity.

### Interpreting disengage performance

Waymo 安全驾驶员的避障表现，不代表人类驾驶员的避障表现。 > Care should be taken in drawing conclusions based on the collision-avoidance performance of Waymo’s trained operators during disengagements, which for the reasons described below, is not predictive of the collision-avoidance performance of the overall population of human drivers.

Waymo 驾驶员和普通人类驾驶员的区别在哪里呢？

1. 受过专业培训： Waymo vehicle operators are selected from a subset of the driving population with good driving records and receive instruction specific to Waymo AVs, defensive driving training, and education regarding fatigue.
2. 避免被打扰：When operating a vehicle, strict rules are in place regarding handheld devices including cell phones and operators are continually monitored for signs of drowsiness.
3. 注意力更集中：Unlike drivers in human-driven vehicles, while the AV is in self-driving mode, Waymo’s trained operators do not execute navigation, path planning, or control tasks, but instead are focused on monitoring the environment and the Waymo Driver’s response to it.

Trained vehicle operators are therefore able to focus their full attention on being ready to disengage and execute collision avoidance, and their performance at this task is expected to be superior to that of a human in a traditional driving role.

### Future work

We expect and invite other safety researchers to review the events and mileages presented here and make their own findings regarding the safety performance of Waymo’s operations demonstrated in this data.

# Conclusion

Taken together, these 47 lower severity (S0 and S1) events (18 actual and 29 simulated, one during driverless operation) show significant contribution from other agents, namely human-related deviations from traffic rules and safe driving performance.

The frequency of challenging events that were induced by incautious behaviors of other drivers serves as a clear reminder of the challenges in collision avoidance so long as AVs share roadways with human drivers.

• 和人类现有数据比较，碰撞分布发生变化；可以认清楚自动驾驶的优点 (机器稳定以及不知疲倦)以及劣势，优点可以及早加以利用，但是如何规避缺点却是一个难点。 > Due to the typology of those collisions initiated by other actors as well as the Waymo Driver’s proficiency in avoiding certain collision modes, the data presented shows a significant shift in the relative distributions of collision types as compared to national crash statistics for human drivers.

• 这是业界首次发布百万英里自动驾驶中的碰撞事故。评估自动驾驶汽车安全性没有标准的方法，Waymo 作为行业领头羊的担当，希望通过公布这些数据，推动政策制定者、研究人员甚至其他公司承担制定通用框架的任务。 > This is the first time that information on every actual and simulated collision or contact has been shared for millions of miles of automated driving.
> The most significant long-term contributions of this paper will likely not be the actual data shared, but the example set by publicly sharing this type of safety performance data and the dialogs that this paper fosters.

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# 什么是不持有的生活

“不持有的生活”中应该“不持有”的物品，可以分为以下 4 种： 1. 超出自己管理能力的物品，不持有。 2. 不钟爱的物品，不持有。 3. 无法回收利用或转送给他人的物品，不持有。 4. 不适合自己、与自己的生活方式不相符的物品，不持有。

“不持有的生活”侧重于物品的质量和适合度，能够减少物品的数量，也能减轻自己的劳动量。在实践这种“不持有的生活”时，以衣服整理为例，四季所穿的衣服数量不会很多，能够整齐地叠放在塑料整理箱中，或是挂在衣橱里，根本不需要那种放衣服的多屉柜；地板和家具上如果没有太多东西的话，只要用吸尘器和抹布，短短一刻钟就能将家中所有的地方清洁好，整个房间都会给人一种唤然一新的感觉。

# 实用好建议

• 如果你打算在跳蚤市场上卖掉不需要的东西，最好选择那些与季一节相吻合或略早于时令的东西。例如，在 5 月的黄金周时，出售夏季的单衣，肯定会卖个不错的价钱。
• 如果“东西”也可以看做是“时间”的代名词，或许“继续保留”便意味着执著于过去，而过量地“准备”则是种对未来的担忧，这也许是一种逃避现实生活的举动，而唯有“不持有的生活”是珍惜现在的生活。
• 如果要丢掉一些东西，可以给那些不太重要或体积很大的东西拍下照片，比如纸箱子，做好拍照记录，然后处理掉就可以了。
• 东西是具有互补性的，替代性比较强，活用现有物品。例如一年可能只用到一次的漏斗，就用现有的塑料板卷成漏斗状来代替，如此就能避免多持有一个东西。
• 如果没有家用碎纸机，那么纸张泡在水里会自动溶解为纤维。
• 把纸质资料收集到一起，如果一年都不会翻动，那么可以放心丢掉，不会有重要的东西遗漏。
• 衣服按种类找到到底缺失什么，平衡生活，而不是看到喜欢的就买下来。
• 不常用的东西，可以租赁，虽然价格会比较贵，但是这是精简生活的代价，自己不用后续维护，整体经济负担小。
• 对于报纸和宣传单，我们可以折叠制作一个简易纸盒，可以用做暂时的收纳盒或垃圾盒。

• 电热水壶使用起来很不经济和方便。每一次喝水，都要重新加热一次，拥有那种保温性较好的水壶也可以满足你的需要。
• 已践行，保温壶让家里随时有热水喝，避免喝千滚水。
• 哪怕就写一行字，也要开始写日记，而往往一开始，就可以写很长的字。
• 尽量不要购买干电池，而是使用充电电池。
• 制作购物清单，多思考几次，反复询问自己是否真正需要呢？
• 提高常用物品的质量。
• 自己在没有购买 airpod 耳机之前，总是会尝鲜不同的蓝牙耳机，但是购买足够好的 airpod 后，自己再没有胡乱购买过任何一款耳机，甚至看到不看。

# References

2020 年 12 月，我和苗苗一起去山西大同参加朋友的婚礼，顺道在大同多做停留，来粗略地游览大同风光。

# 第一天

12月12日，下午我们来到大同市内比较有名的 华严寺 和 仿古城墙 参观。

## 华严寺

• 倾斜的佛像：在大雄宝殿内，一部分雕像是倾斜的。专家给的解释是倾听人间疾苦。我自己推测，因为室内是一排佛像，如果完全排列整齐，难免后面的佛像就被前排的佛像遮挡起来，不容易看到；后面的佛像倾斜起来，更容易进门就看到。
• 壁画：华严寺中，基本每一间佛堂都有精美的笔画，高大威武，讲述佛教中的一个个典故。有些壁画上佛像额头和鼻梁被涂上浅白色，和黄色的皮肤对比，有点像现在的打高光，难道古人那时候就懂？
• 合掌露齿菩萨：在庄严的佛堂上，一个合掌露齿的菩萨，与封建教条格格不入。

• 木塔：这是一座完全由木头搭建的宝塔，现在游客可以上到顶楼，从高处观看大同的景色。

# 第二天

## 云冈石窟

• 除了昙曜五窟外，云冈石窟中的其他窟，基本都已经损毁和风化比较严重，看一眼少一眼。
• 雕刻之薄：石窟之间是分离的，但相邻两窟最薄的地方仅有几厘米，你很难想象古人是如何精准测得厚度，然后在薄薄的石面上施工的。
• 大佛的因祸得福：这个佛像本来是，但是因为塌陷暴露在外面，但是上面的山体防止雨水下漏侵蚀，所以上半部分的岩体完好地保存下来，看起来栩栩如生。
• 石窟内的佛像，大的有十几米高，小的只有几厘米高，甚至有雅典风格的千佛立柱(风化很严重)。

# 旅行建议

• 大同地处河北省北部，处于关外风口，冬天特别冷，经常零下十几度，所以冬季旅行需要穿上厚衣服。
• 2020 年下半年，山西省周一至周五工作日向全国游客免首道门票的 A 级旅游景区，也就是工作日预约就能免门票参观；周六和周日则需要全价门票参观，对外地人周末旅行不是很友好，建议工作日旅行。
• 大同曾经是煤炭资源性城市，环境污染严重，但是经过这些年的治理，蓝天已不再是奢求，大同的天空还是非常美的。
• 古建筑是一门深奥的学位，如果想探究一二，最好预先做一些学习，然后参观时尽量听导游讲解，不白来，不光看热闹。

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# 轻整理

1. 文件检索：在一个项目刚开始的时候，文件夹中没有文献，就需要先建立一份本地的文献原始积累，我习惯在 Web of Science 和 Google Scholar 上根据关键词去找所需要的文献。 > Web of Science 是全球最大、覆盖学科最多的综合性学术信息资源，收录了自然科学、工程技术、生物医学等各个研究领域最具影响力的超过8700多种核心学术期刊。利用 Web of Science 丰富而强大的检索功能--普通检索、被引文献检索、化学结构检索，您可以方便快速地找到有价值的科研信息，既可以越查越旧，也可以越查越新，全面了解有关某一学科、某一课题的研究信息。

2. 文件整理：Mendeley 会自动提取文献信息，按照文献的发表年份，期刊，和文章题目将文献重命名，并将该文献自动整理到指定文件夹中，完成文献的原始积累。 > 我设置 Mendeley 自动根据文献的三个强信息：发表年，发表期刊，和文章题目自动重命名，并结合 everything，在本地实现文献的第一重搜索。

3. 同步：Mendeley 自带同步改能，如果文献量不是很大，那么可以使用 Mendeley 自带的云空间来同步自己的文献。这样做的好处就是，把所有的文献和笔记信息全部集中化了，不会造成信息碎片。 > 如果同步空间不够，那么可以在Mendeley上保留自己的批注，利用 dropbox 等云盘同步 Mendeley 的文件夹中所有文献；之后看文献时，只需要从这个文件夹中打开文献即可。

4. 信息处理：做笔记也可以只在 PDF 上做，这样就不用另外开一个软件写笔记，并可以对自己感兴趣的信息直接标注，实现信息最大程度集中化

# 如何指定文档不被Mendeley数据库收录

We have a checkbox in the Document Details panel that allows you to keep that entry from being aggregated. It will still be synchronized across your multiple devices, but it will not have the Document Details aggregated to our research catalog.

In summary, if you’re adding a document and you don’t want the document details to be anonymously aggregated and made available for search in our research catalog, then go ahead and click on the “Unpublished work” checkbox in the Document Details panel on the right.

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# 精彩摘录

## 酒婆

• 好酒应是温厚绵长，绝不上头。但穷汉子们挣一天命，筋酸骨乏，心里憋闷，不就为了花钱不多，马上来劲，晕头涨脑地洒脱洒脱放纵放纵吗？

## 死鸟

qiāng毛：长得不顺的兽毛，耷拉翅膀

## 冯五爷

• 中国人想赚钱，第一个念头便是开饭馆。民以食为天，民为食花钱；一天三顿饭，不吃腿就软，钱都给了饭馆老板。
• 燃鞭放炮
• 买卖赛人，靠一股气儿活着，气泄了，谁也没辙。愈少客人，客人愈少；油水没油，伙计散伙。
• 趿拉一双破鞋。

## 蓝眼

• 古玩行中有对天敌，就是造假画的和看假画的。造假画的，费尽心机，用尽绝招，为的是骗过看假画的那双又尖又刁的眼；看假画的，却凭这双眼识破天机，看破诡计，捏着这造假的家伙没藏好的尾巴尖儿，打一堆画里把它抻出来，晾在光天化日底下。

• 人家在暗处闹，自己在明处赢。

## 背头杨

• 女扮男装 ## 认牙 ## 青云楼主

• 他于书画这行，是又在行里，又在行外。文人落到这地步，那股子“怀才不遇”的滋味，是苦是酸，还是又苦又酸，只有他自己知道了。

• 半斤八两的尴尬
• 乾旋地转，运气有变。

• chēn出一封信

## 小杨月楼义结李金鳌

• 民国二十八年，龙王爷闯进天津卫，大小楼房全赛站在水里。
• 桌上的茶壶，破嘴缺把，磕底裂肚，盖上没疙瘩。
• 锅伙们把钱截着柜台扔进去就走。
• 转年冬天，上海奇冷，黄浦江冰冻三尺，大河盖上盖儿。
• 小杨月楼说：“二哥真行，您叫我帮忙，又不叫我费劲。这点事还不好办吗？
• MC: 托人办事的最佳方法。
• 杨老板，我这人，向例只交朋友，不交钱。想想看，您和我这段交情，有来有往，打谁手里过过钱？谁又看见过钱？折腾来折腾去，不都是那些情义吗？钱再多也经不住花，可咱们的交情使不完！

## 泥人张

• 谁有钱谁横，官儿也怵三分。

• 能人全都死在能耐上。

## 刘道元活出殡

• 文混混儿却只凭手中一支笔，专替吃官司的买卖家代理讼事。别看笔毛是软的，可文混混儿的毛笔里藏着一把尖刀；白纸黑字，照样要人命。这文混混儿之中，拔尖的要数刘道元。

• 那些武混混儿们来要钱，都是用爬头钉打嘴里把自己的嘴巴子钉在门框上，不给钱不算完。

• 谁料这汉子劲儿奇大，一拳一个，把金三马四打得各一个元宝大翻身。

• 海虾河蟹湖鱼江鳖。

## 皮大嘴

• 北门里的义涌金店先出高招，迎大厅摆一个菜篮子大的鎏金元宝，上边刻六个隶书大字“摸元宝，运气好”，引得人们不买金子也要进门去摸一下，沾沾财气运气。做买卖要的就是人气儿，人多火爆，义涌出了名。
• 叫伙计们用上十天工夫打租界一直贴到北大关，跟着城里城外河东水西宫南宫北，墙头门柱灯杆树干车皮轿厢，就像光绪二十六年义和拳的揭帖，贴满天津城，在哪儿都能瞧见。
• 圆圆小脑袋像杆子上挂的小灯笼。 鎏金。

## 黄金指

• 那年头，人要有钱有势，就一准有人捧。你唱几嗓子戏，他们说你是余叔岩；你写几笔烂字儿，他们称你是华世奎，甚至说华世奎未必如你。

• 码头上耳朵连着嘴，嘴连着耳朵，三天内这话传遍津门画坛。

• 正道干不成，只有想邪道。

## 四十八样

• 买卖二字，一因一果，有人吃就有人做，有人买就有人卖。

• 北京是官场，人们心里边全是大大小小的官儿，喜欢官场的是是非非；天津是市井，百姓心里边就是生活——吃喝玩乐，好吃好喝好玩和有乐子的事都喜欢，还爱看绝活，这卖药糖的本事就五花八门了。

• 人家有的，你未必再有，学人家就不是绝活了。你不是本地人不知道，天津人认绝活，服绝活。

• 绝活一是琢磨出来的，二是练出来的。

• dáo chi：北方方言，指修饰；打扮。

• 你不学人，可挡不住别人学你，你得叫人想学学不去，那才叫绝活。

• 俞家能耐不传女，谁我儿子谁学艺。

• 天津人说话的妙处 -- 既厉害又幽默，既幽默又厉害。单厉害不受听，单幽默不给劲。

## 马二

• 省钱就是赚钱。

• 桌上的鸡腿鱼肚虾腰肉块叫他摘着拣着撂在嘴里，吞在肚里。

## 冷脸

• 人有点倔，性子闷，不好结交，没人知道他的事。
• liào蹶子。
• 说相声就怕人不乐，你不乐等于人家的包袱不gén (滑稽有趣)，活儿使得不绝，栽人家面子。
• 一逗哏一捧哏的两位：
• 逗哏的又高又瘦，像个瘦猴，人偏姓侯；
• 捧哏的又矮又肥，像个胖猫，人偏姓毛。
• 满屋子七八十张热烘烘的笑脸里，有张脸赛铁板，又黑又硬又阴冷。
• 毛猴一使包袱，全场爆笑，笑声要掀去屋顶。

## 一阵风

• 码头上的东西，一半是本地的特产，一半是南来北往的船儿捎来的新鲜货；外来的玩意儿招引当地人，本地的土产招引外来客。

• 个子大赛面墙，肩厚似牛臀，臂粗如大腿，光头圆脸冒红光；浑身的肌肉一使劲，好比上上下下到处肉球，再动两下，肉球满身乱滚。

## 张果老

• 好好一套的老东西失去一件，不成套了，这不成套的东西叫作失群。失群原本是令人惋惜又没辙的事，失群东西的价钱本应大打折扣，到了天津卫的古玩行反倒能拿它赚钱。

• 那股子富丽劲儿，沉静劲儿，滋润劲儿，讲究劲儿，就甭提了，大开门的嘉庆官窑！

• 做买卖的比当大夫的还会察言观色。

• 祖上有钱，本人无能，吃喝之外，雅好古玩，天天在城中转悠。

## 狗不理

• 天津人讲吃讲玩不讲穿，把讲穿的事儿留给上海人。

• 上海人重外表，天津人重实惠；人活世上，吃饱第一。
• 天津人说，衣服穿给人看，肉吃在自己肚里；上海人说，穿绫罗绸缎是自己美，吃山珍海味一样是向人显摆。
• 天津人反问：那么狗不理包子呢？吃给谁看？谁吃谁美。
• 天津人吃的三大样 -- 十八街麻花，耳朵眼炸糕，狗不理包子；玩的三大样 -- 泥人张，风筝魏，杨柳青。

• 这儿讲究的不是材料，是手艺。
• 那时候穷人家的孩子不好活，都得起个贱名，狗子、狗剩、梆子、二傻、疙瘩等等，为了叫阎王爷听见不当个东西，看不上，想不到，领不走。

• 狗子人niān不说话，可嘴上不说话的人，心里不见得没想法。

• 狗子有心眼，花钱买好衙门里的人，在袁大人(袁世凯)用餐时先送上狗不理。人吃东西时，第一口总是香。

## 龙袍郑

• 人出了名就有人说好，有人说坏。一句好话后边总是跟着一堆坏话 -- 恨人有笑人无嘛。

## 陈四送礼

• 人世间最吃得开的有四大样：钱、权、爹、长相。
• 有钱通神，有权比神还顶用，有好爹就是有靠山，长相俊招得人见人爱。
• 可是单这些还不行。有钱有权还得会使，有爹有长相还得会用，这里边有一件要紧的东西不能缺 -- 好法儿。
• 官场从来路不平，有礼如履平地，没礼寸步难行。

## 燕子李三

• 愈见不着愈瞎猜，愈猜愈玄愈神愈哏。
• 天津人就好过嘴瘾，往里是吃，往外是说；说美了和吃美了一样痛快。
• 气得荣禄一狠劲咬碎一颗后槽牙。

## 鼓一张(杨柳青)

• 天津卫的杨柳青有灵气，家家户户人人善画；老辈起稿，男人刻版，妇孺染脸，孩童填色，世代相传，高手如林。
• 年画一年鼓一张，不知落到哪一方。

## 洋相

• 有时玩不好，一个趔趄摔屁股蹲儿，或者四仰八叉趴在冰上，引来众人齐声大笑。

## 黄莲圣母

• 这便是红灯照出名的“踩城”；踩城就是压邪气，震洋人。

• 这时候，关于黄莲圣母的说法又多又神，却一直也没人见到她的模样。想想看，一个女子，能带数千女兵，威镇津城，叫朝廷命官一品大臣也弯下腰来，还飞身杀入洋人刀枪中出生入死，能是凡人吗？若是凡人，不就更叫人佩服得五体投地了？

## 甄一口

• 身子里的酒必得排出去，俗话叫出酒。能喝酒的人必能出酒，出酒的地方各不相同。有的尿，从下边排出来；有的倒，从上边吐出来；有的冒汗，从浑身汗毛眼儿发出来。

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# Speaking

## Part 1

• What work would like to do in the future?
• It's to be an Autonomous Driving Engineer in the future. Autonomous Driving is transforming the transport, which can lessen the traffic problems caused by human drivers, a very meaningful career. Besides, I can put what I have learned at school into practice.
• What's you favorite weather?
• I like sunny ['sʌnɪ adj.阳光充足的;快活的] weather in the daytime, since I can spend time outdoors without suffering ['sʌfə vi.遭受,忍受;受痛苦] from the cold & rain. Yeah, I enjoy practicing sports and ==being out in the nature== because it makes me feel alive [ə'laɪv adj.活着的;活泼的;有生气的].
• What you did last week? > I finished /ˈfɪnɪʃt/ a slide presentation in my work, and I read a book called <Poor dad, Rich dad> in the weekend, and it inspired me on many levels.
• How often do you use you mobile phone? > On a daily basis, almost every moment. I like using my mobile phone to contact /ˈkɒntækt/ my friends online and keep up to date with them, and reading the latest news from the internet. I can have a good relationship with my friends and know what happens in the world via /ˈvaɪə/ prep. 经由，通过 a mobile phone.

## Part 2

• presentation /ˌpreznˈteɪʃn/
• library /ˈlaɪbrəri/
• Dr.

## Part 3

• A technology you want to own (电子产品)

## Part4

• 如何从 hotel 到达 theme park
• 自己只会说 turn left，和一些方位词，却没有额外的信息。

## Part5

• 锻炼身体类话题
• do regular exercice 为什么重要
• sleep for 8 hours 重要吗
• what's the difficult for sb in exercise
• how to keep fit
• 锻炼身体和饮食

# Writing

• 朋友在你的城市找到工作
• 在一个海边度假的酒店，为什么选择它，喜欢和不喜欢什么，会推荐这个酒店的地方吗（location of the hotel）

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# iptables 规则来阻止特定 IP 访问

1. 安装 iptables 防火墙
1. 清除已有 iptables 规则

2. 屏蔽指定 IP

3. 查看已添加的iptables规则

4. iptables的开机启动及规则保存

5. 重启后生效

6. 即时生效，重启后失效