【正文】 Festival. In this day, girls will throw a sewing needle into a bowl full of water on the night of Qixi as a test of embroidery skills. If the needle floats on top of the water instead of sinking, it proves the girl is a skilled embroiders. Single women also pray for finding a good husband in the future. And the newly married women pray to bee pregnant quickly. Tradition transformed The love story of Niulang and Zhinu, and the Qixi Festival have been handed down for generations. Yet these ancient traditions and customs are slowly dying out. Many modern Chinese, particularly youngsters, seem to know more about St Valentine39。 9 / 11 結(jié)束語 本設(shè)計完成的基于 PLC 的煤礦礦車防跑車系統(tǒng)能夠完成以下工作內(nèi)容： 1 能夠有效的對擋車欄進行控制，分為手動控制和自動控制兩種方式； 2 能夠?qū)ΦV車的運行狀態(tài)進行實時監(jiān)控，當(dāng)?shù)V車運行出現(xiàn)問題時可及時報警并控制擋車欄對礦車進行攔截； 本設(shè)計成果也存在一些問題，由于條件所限，本次設(shè)計只能完成模擬實驗，如運用在實際中，電壓穩(wěn)定、工作環(huán)境等都可能對系統(tǒng)產(chǎn)生影響，造成系統(tǒng)出現(xiàn)一些誤差。圖 24 為位置檢測系統(tǒng)邏輯流程。 6 / 11 為電機反轉(zhuǎn)輸出，控制擋車欄關(guān)閉。 ● 豐富的功能擴展模塊 (最大可擴展 7 個模塊 )。 PLC 接收到礦車位置檢測信號，計算出礦車的運行的速度，若礦車超速則控制絞車電機開啟擋車欄， 鋼絲繩網(wǎng)將礦車的動能轉(zhuǎn)換為彈性勢能，然后通過吸能器把彈性勢能吸收，礦車安全平穩(wěn)停下，避免事故發(fā)生。 煤礦礦車防跑車系統(tǒng) 主要由核心控制器、位置檢測系統(tǒng)、擋車欄系統(tǒng)、監(jiān)控報警系統(tǒng)等部分組 。在斜巷礦車移動中，由于絞車司機的違章作業(yè)、信號把鉤工的不規(guī)范推車、連掛車和礦車連接裝置的不完好等原因 ,易發(fā)生跑車事故。為了解決這一問題，多數(shù)煤礦選擇在斜井中安裝擋車欄裝置，擋車欄裝置可以有效的對發(fā)生跑車的礦車進行攔截，避免 造成重大人員傷亡及財產(chǎn)損失。本論文以作者研究的基于 PLC 的 煤礦礦車防跑車系統(tǒng) 項目為背景，從 PLC 控制系統(tǒng)設(shè)計的角度，探討 PLC 控制技術(shù)的應(yīng)用。 關(guān)鍵詞： PLC 擋車欄 控制系統(tǒng) 通訊 2 / 11 前 言 斜井軌道提升時煤礦提升系統(tǒng)中的一個重要組成部分，但目前斜井軌道提升系統(tǒng)在運行過程中跑車事故發(fā)生頻率較高，是煤礦安全生產(chǎn)的薄弱環(huán)節(jié)。要求設(shè)計一個由 PLC 自動控制的擋車欄系統(tǒng)，由位置傳感器檢測車輛有無并計算車速，若礦車超速則自動開啟擋車欄攔截礦車，可有效的減少由礦車跑車造成的損失。以下的單軌提升運輸斜巷中運行，當(dāng)斜巷礦車發(fā)生跑車時，將會造成很大安全事故，造成人身設(shè)備傷亡。 2 系統(tǒng)閉環(huán)控制原理 由擋車欄的工作原理可知，每次擋車欄的開啟，與礦車在斜坡上的運動速度有關(guān)，當(dāng)速度大于某個設(shè)定值時，擋車欄自動啟動。 ● 布爾量的運算速度 ()。 ～ 為擋車欄開啟上限和下限返回信號。使用西門子公司的 STEP7MicroWIN SP6 編程軟件。 圖 26 礦車啟動條件 8 / 11 在自動控制擋車欄程序中必需考慮的另一個方面是礦車停止運行的條件， 當(dāng)正常的絞車停止或者手動按下停止按鈕，或者遇到一些故障情況，程序?qū)⒆詣油Ｖ菇g車工作。s largest virgin forest, and known for its spring and ecological environment, Arxan is marveled at by many tourists as the purest land on earth. You cannot miss out the Autumn of Arxan. It is definitely the best with brightlycolored scenery full of emotions. Autumn in the northern part of the country es earlier than the South. A September rain followed by the footprints of Autumn brings more colors to the once emerald green mountain and blooming grassland. Shutterbugs flock to see for themselves the marvel of splendid colors around the mountains and waters, many of whom have travel a long distance and even camp here only to capture a moment of the nature wonder. The silver birch turns golden, while the larch is still proudly green. You will find yourself drowned in the intoxicating red of the wild fruits as well as the glamour of flowers in full blown. And your heart will be lingering on the woods as it39。s Day! in shops, hotels and restaurants. But few young women will mark the festival with their boyfriends, or take part in traditional activities to pray for cleverness. A largescale of exhibition on the Silk Road opened to the public in the National Museum on Thursday. The exhibition displays more than 400 treasures from Shaanxi province, Gansu province and 14 other regions. It is largest scale exhibition that shows the history of the Silk Road in recent years. As APEC is going on in Beijing, the exhibit aims to show the world this brilliant section of history. The Silk Road is a series of trade and cultural transmission routes that were central to cultural interaction through regions of the Asian continent. It connected the West and East by linking traders, merchants, pilgrims, monks, soldiers, nomads, and urban dwellers from