【導(dǎo)讀】測試是人類認(rèn)識自然、掌握自然規(guī)律的。實踐途徑之一，是科學(xué)研究中獲得感性材料、接受自然信息的途徑，是形成、發(fā)展和檢驗自然科學(xué)理論的實踐基礎(chǔ)。信息一般理解為消息、情報或知識。傳感器是一種以一定的精確度把被測量轉(zhuǎn)換為與之有確定對應(yīng)關(guān)系的、便于應(yīng)用的另一種量的測量裝置。是根據(jù)一定的目的和要求，獲取有限的、觀察著感興趣的某些特定的信息。研究任務(wù)相聯(lián)系的、最有用的、表征特征的有關(guān)信息，而不是企圖獲得該事物的全部信息。含信號處理功能）的組成框圖，并說明各組成部分的作用?？陀^存在或運動狀態(tài)的特征。相應(yīng)地對信號也有有用信號和干擾信號的提法，但這是相對的。在該范圍內(nèi)規(guī)定了測量儀器儀表的不確定度限。測試數(shù)據(jù)用表格列出或畫成曲線；5）對測試數(shù)據(jù)進(jìn)行必要的處理，根據(jù)處理結(jié)果，可以確定傳感器的線性度、靈

　　

【正文】 both Chinese and foreign experts and businessmen since it took effect on Sept 1 last year. The program permits citizens from 51 countries and regions including the United States, Australia, Canada and Japan who have valid visas and flight tickets to a third country to spend three days in the city. The capital of Sichuan province is the first city in the western region of China to offer foreign tourists a three day visa and the fourth nationwide to adopt the policy following Shanghai, Beijing and Guangzhou. Li Zhiyong, deputy dean of the tourism institute at Sichuan Uni versity, said the move contributes to a large increase in the number of overseas tourists and raises the city39。s level of internationalization. The policy will also bring direct economic revenue, Li said. Chengdu has many cultural legacies and is also a paradise for panda lovers with the world39。s largest breeding and research center. Three days are long enough for foreign visitors to visit those iconic tourist spots, he noted. The city is home to the remains of the Jin sha civilization that dates back m ore than 3,000 years as well as the Qing cheng Mountains and the Du jiang yan irrigation system. Qing cheng has long been recognized as the birthplace of Taoism, China39。s ancient indigenous religion, while Du jiang yan is considered to be the oldest functioning watercontrol project in the world. Chengdu ranked third in tourist facilities, management and services among 60 Chinese cities in a customer satisfaction survey released last year. But, Li added that efforts are still needed to develop more tourism products, improve English services and provide accurate translation of traffic signs and scenic billboards. Zhao Yun, chairwoman of British Chamber of Commerce Southwest China, told China Daily that his colleagues found the policy very convenient. A British client once flew here and stayed for just one day to check her ordered goods, she said. Zhao was born in Shanxi province, but she has lived in Chengdu for more than 10 years. My life was like a running race moving from place to place. I also lived in Beijing and Shanghai before, she said. But Chengdu is a place that you never want to leave once settling down. It is now my second hometown, she said. If the environment is further improved, the city will attract more people to visit and live, with the 72hour visafree policy and pelling conditions in transportation, culture, climate and cuisine, he said. Foreigners also gave positive feedback on the policy. A spokesman from Dell Inc said the pany has a global hub of operation in Chengdu, so the threeday visa has an immediate and positive influence on the pany39。s business development. Rudy Buttignol, president of the public broadcasting pany in British Columbia, Canada, said his work requires frequent travel to Chengdu and the policy makes the trips easier. Data from the city39。s public security bureau shows some 100 foreign visitors enjoyed the 72 hour policy by the end of March, most of them from the United States, the United Kingdom and Germany. Chengdu also reported robust growth in its overall tourist industry last year. Official statistics show that it received some 150 million tourists last year, an increase of 28 percent from 2020. Around million came from abroad, an increase of 12 percent. Tota l revenue from tourism surpassed 133 billion yuan ($). During his visit to Kazakhstan in September, Chinese President Xi Jinping proposed that China and Central Asia join hands to build a Silk Road economic belt to boost cooperation. The idea has been widely echoed in Central Asian countries, being an encouraging blueprint for Chinese areas along the Silk Road that has linked Asia and Europe for more than 2,000 years. In the next three weeks, China Daily reporters will travel through the belt in China and in Kazakhstan, Uzbeki stan and Turkey. They will show the progress and expectations of the countries, businesse s and peoples on the route. Shaanxi the start of the ancient Silk Road has positioned itself as the new starting point for the development of the Silk Road Economi c Belt, which will strengthen China39。s cooperation with Central Asian countries, a senior official said. Shaanxi Governor Lou Qinjian said the province is fresh, rich and unique, as it was when it anchored one end of the ancient S ilk Road. It is the best option for acmodating industrial transfers from East China or the world at large, he said on Wednesday in Xi39。an. 15 Lou held a joint interview with 27 media, including China Daily, the first in a series of interviews entitled Chinese Media A long the Silk Road. The interviews will be in Shaanxi and Gansu provinces and the Xinjiang Uygur autonomous region, as well as Kazakhstan, Uzbekistan and Turkey. The media group held the first interview on Wednesday morning in Xi39。an, the starting point of the ancient Silk Road, a trade channel established more than 2,000 years ago linking China, Central Asia and Europe.