以后再也不用担心写爬虫ip被封，不用担心没钱买代理ip的烦恼了 在使用python写爬虫时候，你会遇到所要爬取的网站有反爬取技术比如用同一个IP反复爬取同一个网页，很可能会被封。如何有效的解决这个问题呢？我们可以使用代理ip，来设置代理ip池。 现在教大家一个可获取大量免费有效快速的代理ip方法，我们访问西刺免费代理ip网址 这里面提供了许多代理ip，但是我们尝试过后会发现并不是每一个都是有效的。所以我们现在所要做的就是从里面提供的筛选出有效快速稳定的ip。 以下介绍的免费获取代理ip池的方法： 优点：免费、数量多、有效、速度快 缺点：需要定期筛选 主要思路： 从网址上爬取ip地址并存储 验证ip是否能使用-（随机访问网址判断响应码） 格式化ip地址 代码如下： 1.导入包 import requests from lxml import etree import time 1 2 3 2.获取西刺免费代理ip网址上的代理ip def get_all_proxy(): url = 'http://www.xicidaili.com/nn/1' headers = { 'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36', } RESponse = requests.get(url, headers=headers) html_ele = etree.HTML(RESponse.text) ip_eles = html_ele.xpath('//table[@id="ip_list"]/tr/td[2]/text()') port_ele = html_ele.xpath('//table[@id="ip_list"]/tr/td[3]/text()') proxy_list = [] for i in range(0,len(ip_eles)): proxy_str = 'http://' + ip_eles[i] + ':' + port_ele[i] proxy_list.append(proxy_str) return proxy_list 1 2 3 4 5 6 7 8 9 10 11 12 13 14 3.验证获取的ip def check_all_proxy(proxy_list): valid_proxy_list = [] for proxy in proxy_list: url = 'http://www.baidu.com/' proxy_dict = { 'http': proxy } try: start_time = time.time() RESponse = requests.get(url, proxies=proxy_dict, timeout=5) if RESponse.status_code == 200: end_time = time.time() print('代理可用：' + proxy) print('耗时:' + str(end_time - start_time)) valid_proxy_list.append(proxy) else: print('代理超时') except: print('代理不可用--------------->'+proxy) return valid_proxy_list 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 4.输出获取ip池 if __name__ == '__main__': proxy_list = get_all_proxy() valid_proxy_list = check_all_proxy(proxy_list) print('--'*30) print(valid_proxy_list) 1 2 3 4 5 技术能力有限欢迎提出意见，保证积极向上不断学习 ———————————————— 版权声明：本文为CSDN博主「彬小二」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接及本声明。 原文链接：https://blog.csdn.net/qq_39884947/article/details/86609930
上传时间： 2019-11-15
上传用户：fygwz1982
This research work aims at eliminating the off-chip RF SAW filters from fre- quency division duplexed (FDD) receivers. In the first approach, a monolithic passive RF filter was constructed using on-chip capacitors and bondwire inductors. The bond- wire characteristics were studied in details and the effect of mutual inductive coupling between the bondwires on the filter performance was analyzed. Based on that, a bond- wire configuration was proposed to improve the frequency RESponse of the filter. The filter was implemented in 0.18 µm CMOS process for WCDMA applications.
标签： Interference Mitigation Techniques
上传时间： 2020-05-27
上传用户：shancjb
The first question most readers of an O’Reilly book might ask is about the choice of the cover animal. In this case, “why a duck?” Well, for the record, our first choice was a unicorn decked out in glitter and a rainbow sash. That RESponse always gets a laugh (we are sure you just giggled a little), but it also brings to the surface a common perception of software-defined networks among many expe‐ rienced network professionals. Although we think there is some truth to this perception, there is certainly more meat than myth to this unicorn.
标签： Networks Software Defined SDN
上传时间： 2020-06-01
上传用户：shancjb
It has been said that the move from narrowband to broadband access is the second revolution for the Internet — ‘broadband is more bandwidth than you can use’. Once users have experienced broadband access there is no turning back. A whole new world of applications and services becomes possible. No longer is it the ‘world- wide wait’. The speed of RESponse and visual quality enabled by broadband finally allows the Internet to reach its true potential.
上传时间： 2020-06-06
上传用户：shancjb
n its Framework and Roadmap for Smart Grid Interoperability Standards, the US National Institute of Standards and Technology declares that a twenty-first-century clean energy economy demands a twenty-first-century electric grid. 1 The start of the twenty-first century marked the acceleration of the Smart Grid evolution. The goals of this evolution are broad, including the promotion of widespread and distributed deployment of renewable energy sources, increased energy efficiency, peak power reduction, automated demand RESponse, improved reliability, lower energy delivery costs, and consumer participation in energy management.
上传时间： 2020-06-07
上传用户：shancjb
n present power system, the engineers face variety of challenges in planning, construction and operation. In some of the problems, the engineers need to use managerial talents. In system design or upgrading the entire system into automatic control instead of slow RESponse of human operator, the engineers need to exercise more technical knowledge and experience. It is principally the engi- neer’s ability to achieve the success in all respect and provide the reliable and uninterrupted service to the customers. This chapter covers some important areas of the traditional power system that helps engineers to overcome the challenges. It emphasizes the characteristics of the various components of a power system such as generation, transmission, distribution, protection and SCADA system. During normal operating conditions and disturbances, the acquired knowledge will pro- vide the engineers the ability to analyse the performance of the complex system and execute future improvement
上传时间： 2020-06-07
上传用户：shancjb
Multisim官方示例Multisim仿真例程基础电路范例135例合集:Chapter 1 - RLC CircuitsChapter 2 - DiodesChapter 3 - TransistorsChapter 4 - AmplifiersChapter 5 - OpampsChapter 6 - FiltersChapter 7 - Miscellaneous CircuitsFundamental Circuits.pdf004 Parallel DC Circuits.ms10005 Series-Parrallel DC Circuit.ms10006 Current Analysis.ms10007 Millmans Theorem 1.ms10008 Millmans Theorem 2.ms10009 Kirchhoff's Current Law.ms10010 Thevenin's Theorem.ms10011 Superposition Principle.ms10012 Nortons Theorem and Source Conversion.ms10013 AC Voltage Measurement.ms10014 Frequency RESponse of the Series RL Network.ms10015 RL High and Low Pass Filter.ms10016 Frequency RESponse of the Series RC Network.ms10017 RC High and Low Pass Filter.ms10019 Center-Tapped Full-Wave Rectifier.ms10020 Bridge Rectifier.ms10021 Capacitor-Input Rectifier Filter.ms10022 Diode Clipper (Limiter).ms10023 Diode Clipper.ms10024 Diode Clamper (DC Restorer).ms10025 Diode Voltage Doubler.ms10026 Zener Diode and Voltage Regulation 1.ms10027 Zener Diode and Voltage Regulation 2.ms10028 Zener Diode and Voltage Regulation 3.ms10105 TTL Inverter.ms10107 TTL Gate.ms10109 OR Gate Circuit.ms10111 Over-Damp Circuit.ms10113 Critical-Damp Circuit.ms10115 Series RLC Circuit 1.ms10117 Clapp Oscillator.ms10119 Differential Amplifier 1.ms10121 Differential Amplifier in Common Mode.ms10123 LC Oscillator with Unity Gain Buffer.ms10125 Notch Filter.ms10127 PNP Differential Pair.ms10129 Crossover Network.ms10131 Second-Order High-Pass Chebyshev Filter.ms10133 Third-Order High-Pass Chebyshev Filter.ms10135 Fifth-Order High-Pass Filter.ms10
标签： multisim
上传时间： 2021-10-27
上传用户：trh505
对某四轮独立驱动电动汽车轮毂电机进行研究,设计一种永磁无刷直流电机控制器.以STM32F103RBT6芯片为基础,对电机驱动电路、采样电路和保护电路分别进行硬件设计与分析;同时,采用模块化软件设计方案,对该控制器的软件系统进行升级.实验验证表明:所设计的电机控制器能使电机响应迅速、转速稳定、无超调,且电动车动力输出性能良好.A permanent magnet brushless direct current motor controller was designed by studying the hub motor of a four-wheel independent drive electric vehicle.Based on STM32 F103RBT6 chip,the hardware design and analysis of motor drive circuit,sampling circuit and protection circuit were carried out respectively.At the same time,modular software design scheme was adopted to upgrade the software system of the controller.Experimental results show that the designed motor controller can ensure the motor fast RESponse,stable speed,no overshoot,and good power output performances.
上传时间： 2022-03-26
上传用户：qingfengchizhu
随着电磁阀在工业和日常应用的增多,其功耗越来越被人们所重视。通过对电磁阀驱动电路的研究,设计一套电磁阀节能驱动电路。不仅提高了电磁阀的响应时间,更重要的是降低了功耗,使电磁阀由工作在大电流状态下,变成大电流启动小电流维持的工作状态。减少了由电流过大引起的电磁阀线圈过热,增加了电磁阀的安全性。The power consumption of an electromagnetic valve is drawing increasingly more attentiori as it is widely used in industrial production and daily life. In this study, an energy - saving driving circuit of electromagnetic valves was designed. It can make an electromagnetic valve to start with a high current while work with a low current; thereby the power consumption can be reduced. Besides, it can shorten the RESponse time of an electromagnetic valve and improve the security of the valve.
上传时间： 2022-04-16
上传用户：
以STM32F103C8T6为核心,设计了无刷直流电机控制器硬件电路。电路主要包括IR2310构成的PWM驱动电路、IRF3808构成的逆变电路、增量式旋转编码构成的速度反馈电路。控制器具有CAN和RS232通信接口,可与计算机或PLC构成速度或位置伺服系统。利用由xPC目标搭建的半实物仿真平台对PI参数进行整定。测试了控制器的速度伺服响应性能,给定速度为2400rpm时,控制器响应时间为0.32s。实验结果表明,系统工作可靠,稳定性好,响应速度快,可以满足上肢康复机器人的机械臂速度控制性能要求。The hardware circuit of Brushless DC motor controller is designed by taking STM32F103C8T6 as the core,which mainly includes PWM driving circuits made up of IR2310,inverter circuit formed by IRF3808,speed feedback circuit composed of incremental rotary encoder and so on.Speed servo control system or position servo control system can be composed of BLDM controller with computer or PLC through CAN communication interface or RS232 serial communication interface.By using the hardware in the loop simulation platform built by xPC target,the PI parameters are set up.The Speed servo RESponse performance of the controller is tested.When the speed is 2 400 rpm,the RESponse time of the controller is 0...
上传时间： 2022-05-07
上传用户：
