英文原文 (1).pdf

基于PLC的植物水分和养分精确调节控制系统的设计【中文3800字】

收藏

压缩包内文档预览:
预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图
编号:10197685    类型:共享资源    大小:547.80KB    格式:ZIP    上传时间:2018-06-14 上传人:闰*** IP属地:河南
15
积分
关 键 词:
基于 plc 植物 水分 水份 以及 养分 营养 精确 调节 调理 控制系统 设计 中文
资源描述:
基于PLC的植物水分和养分精确调节控制系统的设计【中文3800字】,基于,plc,植物,水分,水份,以及,养分,营养,精确,调节,调理,控制系统,设计,中文
内容简介:
【中文 3800 字】2012 年国际医学物理和生物医学工程会议基于 PLC 的植物水分和养分精确调节控制系统的设计刘新卢 光余明 哈尔滨 15040,东北林业大学信息与计算机工程学院摘要基于 SIMATIC S7-300 PLC 控制器精确控制植物生态园土壤中的水分和 K 浓度。建立了基于 PLC 的控制系统硬件,分析了水分和 K 浓度的控制算法,完成了控制系统的软件设计。最后,通过比较两个地块马铃薯产量的数量和质量,证明该控制系统具有实用性和优越性,一个受设计控制器控制,另一个处于自然增长。水和养分是保证植物正常生长发育的必要条件。为了精确控制植物的水肥灌溉和保持植物生长需求,不仅有助于降低水肥施用率,而且有助于植物产生数量和质量。现代农业节水灌溉技术为水肥精确灌溉提供了条件,同时节水灌溉自动化控制技术为实现水肥优化管理提供了保证。美国,以色列,荷兰,加拿大,澳大利亚等发达国家的农业发展了一系列多功能,强大的肥料灌溉控制器2-7 ,而我国灌溉控制系统在试验发展阶段仍处于发展阶段,与发达国家有较大差距。随着水资源的不足,开发一种适合我国土壤特性的节水灌溉控制体系,具有自主知识产权,不仅可以解决缺水状况,而且具有很大的社会效益和经济效益8。鉴于此,本文开发了一套自动调节植物水分,养分的灌溉系统控制器。它的控制核心是西门子公司创建的 S7-300 PLC。通过土壤湿度传感器和离子敏感电极测量土壤水分和氮(N),磷(P),钾(K)等营养物质的含量并输入系统,采用 PID 比例积分控制算法控制系统,输出数字控制信号直接控制水灌系统开启或关闭电磁阀,实现水肥精确控制,确保植物在最佳环境下生长。1.控制系统的硬件设计PLC 是一种通用的自动控制装置,它集成了传统的继电控制技术,计算机技术和通信技术,具有控制能力强,操作灵活,可靠性高,适合连续长期工作的特点。它非常适合于植物生态公园的高效控制要求。9该控制系统主要由土壤湿度传感器,离子敏感浓度电极,变送器,PLC 控制器,PC 等设计而成,如图 1 所示。以 PC 为主机,根据植物生长对水分的需求量和肥料,系统可以实现参数设定,数据通讯,存储,实时显示。并以 PLC作为从属计算机,根据植物生长控制曲线,实现与主机的通讯,实现现场变量检测,数据处理与判断,滴灌与营养液曲线(肥料)的比例与实施。下位机,本文选用 SIMATIC S7-300 系列 PLC 作为控制器核心,采用模块化结构设计,每个独立模块可以广泛组合和扩展。根据控制要求,可以得到控制系统的硬件结构(如表 1 所示)。因为影响植物生长的因素(如温度,湿度,营养液浓度等)大多为多输入,多输出,大时滞的非线性控制变量10。对植物生长的两种影响是在实验中选择作为调节的最大因素(水分和肥料),控制变量为土壤湿度和 K +浓度,两路信号通过相应的湿度传感器输入到 PLC A / D模块(北京联创四源科技公司 FDS100 型)和离子浓度电极(美国 Van London-pHoenix 公司 K001508 型,国内交货数量为 L2850595)。土壤湿度传感器输出420mA 电流,直接接入 PLC 模拟量输入模块 SM331,K +灵敏度选择电极输出信号弱,只有经过变送器信号转换后才能接入 SM331 模块。从控制系统输出的数字量控制信号直接驱动灌溉电磁阀动作,无中间环节。表 1 是 S7-300PLC 的硬件控制器PLC 模块 名称 命令电源模块 PS307 / 5A 6ES7 307-1EA00-0AA0CPU 模块 CPU 314 SM331 6ES7 314-1AG13-0AB0 / v2.6模拟量输入模块 AI812Bit 6ES7 331- 7KF02-0AB0数字输出模块 SM322 DO1624 6ES7 322-1BH01-0AA0图 1 基于 S7-300 PLC 的工厂环境控制系统的结构框架2.控制系统的软件设计2.1 控制算法的研究(1)积分分离控制由于控制变量具有特殊性,典型的 PID 控制算法难以取得较好的控制效果,因此本文采用分离积分(P-PI)控制算法,辅以湿度 PWM自动控制方式和 K 浓度。积分分离控制的主要目的是在物体开始,结束或显着改变初始值时在短时间内避免较大的偏差,也是积分积累过程中的一个大的超调。鉴于此,当偏差的绝对值为 1 0 e(k) | 2,取消积分部分,从而实现积分控制的分离。算法如公式 1 所示。其中u(k) t=k 控制总量 t T T/TI积分时间TD/T微分时间使用分离积分控制具有较小的超调量,以缩短建立时间。由于传统的 PID控制在早期的控制中,积分累积作用过多,导致超调量较大,消除残差的过程较长,但积分分离的积分作用被充分应用于消除残差特征。选择的设计具有以下性能取代原来的固定功能,其优点如下:1 连续性,2功能简单,含有可调参数,含义清晰,设置简单,调节裕度大。这可以使 PID的结构得到充分利用,从 P 到 PI 结构的变化是连续的11。本文选择“,”作为设定值。(2)PWM 控制在本文设计的系统中,输出控制通过固态继电器作用于喷水电磁阀,控制部分采用 PWM 功率(压力)或 PWM,通过控制交流电流来控制功率一段时间的浪潮。该系统通过在一个控制周期内控制固态继电器的连接时间,直接控制侧输入 PWM 控制脉冲波,交流控制输出端与交流电源连接,PWM 波控制交流电路切换,PWM 控制模式实现 PWM 功能输出如图 2 所示。通过调整通电时间,可以调整控制周期的系统功率。图 2 是湿度控制的 PWM 图2.2 控制系统软件组件和控制流程根据以上控制算法,使用 Step7 软件编写和调试控制程序,Step7 软件为用户提供了一个结构化的程序设计,一个用户程序由启动程序组成,主程序和中断响应程序为各种不同的程序模块,操作系统已经设置了这些模块的框架,用户需要做的是根据控制任务的具体要求来控制系统,以分层划分控制任务,并对每个模块化程序进行编程,然后调用这些模块用户主程序中的模块。编程功能的模块化方式使系统更易于管理,并且更便于功能扩展。根据系统功能的划分,将控制任务分解为各个功能模块。通过系统的运行状态和控制指令调用模块。考 虑到植物在生长过程中对周围土壤和空气湿度有一定影响12-14 。根据模块化软件设计思想,该控制系统软件的主程序模块主要包括信号采集滤波模块,现场信号模块,传感器校准模块,自动控制模块,系统输出模块的真值计算。根据控制算法,植物生态园土壤水分控制系统软件流程图如图 3 所示。图 3 土壤湿度控制流程图在本文中,自动控制程序的控制湿度略低于设定值,即当偏差小于 0.05 时,控制器不起作用,只有呼叫控制功能块大于 0.05。通过计算偏差,积分分离呼叫控制算法程序,计算固体继电器控制周期内的通电时间,控制喷嘴阀的开闭。PWM 控制可以实现。根据上述 K 浓度控制算法, K +浓度采用 TP-PID 控制输出作为开关量,系统结构简单,可靠性高,调试容易。只要选择一个正确的时钟脉冲,就可以达到令人满意的控制性能,并且只要将算法结果转换成输出脉冲宽度,然后允许滴下钾盐,设置滴注周期和每个量下降,控制流程图如图 4 所示。3 植物水,营养调控系统性能测试由于控制系统的硬件和软件设计已经完成,校准了室内传感器,然后将整个系统转移到试验中,在实验中,种植马铃薯作为测试水分,营养调节系统性能的一个实例。两个面积均为 100 平方米,马铃薯植株 230 株,在自然条件下给 1 个小区洒水,在设计的控制系统中保持 2 个小区灌溉,经过 100 天的增长,然后在两个区域收获所有土豆,做一个统计分析,结果如表 2,3 所示。表 2 表示马铃薯消耗量在两个地块的一生中的水肥比较情况,从表中可以看出,在控制生长的情况下,对于相同数量的马铃薯,水和肥料的消耗量小于自然生长条件,因此水,营养物质植物调控系统的设计证明了其节能功能。从图 3 可以看出,虽然马铃薯在生长调控下消耗较少的水肥,但马铃薯产量和质量均有所提高,进一步表明所设计的控制系统具有实用性。4 结论本文以 SIMATIC S7-300 PLC 为核心控制器,设计植物水分和养分自动控制系统,应用分离积分(P-PI )控制算法自动控制植物生长所需的水分和养分,完成系统硬件和软件设计,搭建整个控制平台,并进行马铃薯生长调控的对比实验,证明设计的控制系统对减少用水量,提高马铃薯的产量和质量具有一定的效果。该系统的成功完成,为适合我国农业发展的水肥自动灌溉系统研究奠定了基础。表 2 不同生长条件下水肥用量的对比地块号 水(公斤)氮肥(kg) 钾肥消费量(千克)氯化钾数量磷酸盐(kg)自然增长 2365 14.1 3.5 15.6增长规律 1897 10.5 2.7 11.5表 3 不同生长条件下的产量对比号 产量(kg )单株产量(kg )平均尺寸 n(mm)淀粉生产装置的平均数量自然增长 65.8 0.31 30 2.6 15.7增长规律 97.5 0.45 43 3.5 19.1图 4 土壤中 K +浓度控制的流程图参考1马学良,赵启恒,田和红等,全球节水灌溉技术与装备现状与发展J节水灌溉,1999 2 4-72张冰,首起源,李成,全球节水灌溉自动化装备现状与展望J灌溉机械,2003(2)37-413 C.C. Van Donkelaar, R. Huiskes。胚胎生长板中的 PTHrP-Ihh 反馈回路允许PTHrP 控制肥大和 Ihh 以调节增殖J。 Biomechan Model Model Mechanobiol,2007,6 :55-624 Bambang Marhaenanto 和 Gajendra Singh。基于计算机的温室环境控制器的开发。 2002 年 3 月,13,136-1465 J.M.Aaslyng,J.B.Lund,N.Ehler,E.Rosenqvist。 Intelli Grow:一种基于温室成分的气候控制系统J。环境建模与软件 18,2003,2:657-6666 I.S.Smout,S.G.Gorantiwar 。非均匀灌溉方案灌溉水管理绩效评估实例研究J。灌溉和排水系统,2005 年,19(1)37-607 BlaineR.Hanson,DonM.May。美国加利福尼亚州圣华金谷加工番茄的作物蒸散量J。灌溉科学, 2006,24(4):211-2218张兵,智能节水灌溉控制系统设计与研究D,江苏大学博士论文, 20039何世军,徐俊峰,张璐,智能温室系统中控制器免编程的应用J,基础自动化,2000 7(4)53-5410李金柱,农田水利,水资源与工程交易调整效果,2008 19(2)88-9011王茂华,高端农业与工程技术创新J,农业工程交易。 1999 15(1)1-812王庆兵,王恩恒,蒋忠祝等,黑土水分与干旱的常见树木生理特性J,东北林业大学学报,2009 37(1)8-1013王晓东,叶盛新,沉海龙等,不同土壤水分对幼树形态的影响,Zhenbirch 的数量和光合特性J ,东北林业大学交易, 2008 36(5)22-2414姜忠竹,赵玉森,陈香薇,白与珍贝的水分利用效率和光合特性对比J。 2009 37(8 )11-12 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of name organizer 2012 Published by Elsevier B.V. Selection and/or peer review under responsibility of ICMPBE International Committee.Available online at Physics Procedia 33 (2012) 429 4362012 International Conference on Medical Physics and Biomedical EngineeringDesign on the Precise Regulating Control System for Moisture and Nutrient of Plants Based on PLCLiu xin ,Lu Guang,Yu MingSchool of Northeast Forestry University Information and Computer Engineering College, Harbin 15040AbstractThe moisture and the concentration of K in the soil in plant ecological park was accurately controlled based on the SIMATIC S7-300 PLC controller. The hardware of control system based on PLC was set up, at the same time, the control algorithm used in the moisture and concentration of K was analyzed and the software design of control system was also completed. At last, the control system was proved to be practicality and superiority by comparing the quantity and quality of potatoes yield from the two plots, one is controlled by the designed controller and the other is in the natural growth.Open access under CC BY-NC-ND license.Keyword PLC controller, accurately control, the moisture of soil, the concentration of KWater and nutrient is necessary condition to ensure normal growth and development of the plant. To control the water and fertilizer irrigation of plant accurately and to maintain optimum plant growth in demand, it not only helps reduce water and fertilizer application rate, but also helps plants produce the quantity and quality. The water-saving irrigation technology of modern agriculture has provided a condition for accurate irrigation of water and fertilizer, meanwhile, automation control technology in water-saving irrigation has provided a guarantee to achieve optimal control of water and fertilizer. Agriculture in developed countries like the United States, Israel, Netherlands, Canada, Australia has developed a series of versatile, powerful fertilizer irrigation controllers 2-7, and our irrigation control system in the development of the trial is still in development stage, has a larger gap with developed countries. With the lack of water resource, developing a water-saving irrigation control system suitable for the Chinas soil properties ,with independent intellectual property rights can not only solve the water shortage situation, but also has great social and economic benefits 8 .In view of this, this article developed a set of irrigation system controller with automatic1875-3892 2012 Published by Elsevier B.V. Selection and/or peer review under responsibility of ICMPBE International Committee.Open access under CC BY-NC-ND license. doi:10.1016/j.phpro.2012.05.085430 Liu xin et al. / Physics Procedia 33 (2012) 429 436regulation on plant moisture, nutrients. Its controlling core of the system is S7-300 PLC which created by Siemens company. Measure the content of soil water and nitrogen (N), phosphorus (P ), potassium (K) and other nutrient through the soil moisture sensor and ion sensitive electrode and input into system, use PID proportional integral control algorithm to control the system, export digital control signal to directly control the water irrigation system in opening or closing electromagnetic valve, implement accuracy controlling for water and fertilizer, in order to ensure the plant growth in the best environment.1. The hardware design of the control systemPLC is a general-purpose automatic control device, which integrated the traditional relay control technology, computer technology and communication technology, with control capability, operational flexibility, high reliability, and suitable for continuous long-term working characteristics. It is very suitable for high efficient control requirements for plant ecological park. 9 The control system is designed mainly by soil moisture sensor, the concentration electrode of ion-sensitive, transmitter, PLC controller, PC, etc, shown in Figure 1.Taking PC as a host computer, according to plant growth on the demand for water and fertilizer, the system can achieve parameter setting, data communication, storage, real-time display. And take PLC as slave computer to achieve the site variable detection, data processing and judgments, the ratio and implementation of drip irrigation and nutrient solution curve (fertilizer) according to plant growth control curve, implementation of communication with the host computer.The lower machine, this paper selected SIMATIC S7-300 series PLC as controller core, the design of the modular structure, each independent module can be widely combined and extended. According to the control requirements, it can get the hardware structure of the control system (shown in Table 1). Because the factors that affect plant growth (such as temperature, humidity, nutrient solution concentration, etc.) are mostly a multi-input, multiple output, nonlinear control variables of large time delay 10.Two kinds of impacts on plant growth are chosen in the experiment as the biggest factor (moisture and fertilizer ) for regulation, control variables are soil humidity and K + concentration, the two signal input to the PLC A / D module through the corresponding humidity sensor (Beijing LianChuang SiYuan Science and technology company FDS100 type) and ion concentration electrode (U.S. Van London-pHoenix company K001508 type, number of domestic delivery is L2850595). Soil humidity sensor output 4 20 mA of current, direct access to the PLC analog input module SM331, output signal of K + sensitivity selection electrode is weak, it can access to the SM331 module only after the signal conversion of transmitter. Digital quantity control signals which output from control system directly drive irrigation electromagnetic valve action, without intermediate links.Tab. 1 the hardware controller of S7-300PLCPLCModule NAME ORDERPower supply Module PS307/5A 6ES7 307-1EA00-0AA0CPU Module CPU 314 SM331 6ES7 314-1AG13-0AB0/v2.6Analog Input Module AI812Bit 6ES7 331- 7KF02-0AB0Liu xin et al. / Physics Procedia 33 (2012) 429 436 431TDTDigitaloutput ModuleSM322 DO16246ES7 322-1BH01-0AA0Fig. 1 the structure frame of plant entironment control system based on S7-300PLC2. The software design of the control system2.1 control algorithm research(1) Integral separation control As the control variable has the particularity in this paper, it is difficult for the typical PID control algorithm to achieve better control effect, therefore, this paper uses the separated integral (P-PI) control algorithm, supplemented by way of humidity PWM automatic control and K concentration.The main purpose of separation control of Integral is to avoid a large deviation in a short period of time as the object start, end or significantly change the initial value, also a large overshoot as well in resulting of the accumulation of integral. In view of this, to set the two threshold values 1, 2 0, when the absolute value of deviation is 1 2, cancel integral part, thus it can achieve separation of integral control . Algorithm is shown in Equation 1.u (k ) K p e(k ) TkTI i 0 Te(i)K p e(k ) e(k 1) (1)Amongu(k) t=k Control amount T T/TIIntegral time432 Liu xin et al. / Physics Procedia 33 (2012) 429 436TD/TDifferential time0 e(k) 2b 1 e(k) 21 e(k) 1Use separation integral control has a smaller overshoot to achieve a shorter settling time. Because the conventional PID control in the early control, integral accumulated role is too much to lead to large overshoot and long process of elimination of residual, however, the integral role of the integral separation is fully applied to eliminate residual characteristics.The design of choice has the following properties of the function to replace the original fixed one, its advantages are as below: 1 the continuous,2 the function is simple, and contains adjustable parameter with clear meaning, simple setting , a large margin adjustment .This can make the structure of PID is fully used, and the changes from P to PI structural is sliding continuous 11 .This paper choice”, “as the setting value.(2) PWM control In the designed system of this paper, the output control acts on the electromagnetic valve of spray water through the solid state relay, the control part adopts PWM power (pressure) or PWM, which control the power through controlling alternating current wave of a period of time. This system realize the PWM function by controlling on connected time of solid state relay in a control cycle, DC control side input PWM control pulse wave directly, exchange control output end connect with the AC power, PWM wave control AC circuit switching, PWM control mode output is shown in Figure 2. By adjusting the electrifying time, it can adjust system power of a control cycle.u(k 2) u(k 1) u(k)Fig. 2 the PWM illustration of humidity control2.2 Control system software components and control flowAccording to the above control algorithms, use Step7 software to write and debug the control procedures, Step7 software provides users with a structured program design, a user program is composed by the startup program, the main program and interrupt response procedure for a variety of different modules, the operating system has set up the framework of these modules, What the user need do is to control the system according the specific requirements of the control tasks, to hierarchical divide the control tasks ,and to program each modular program, then call these modules in user main program.Modular way of programming functions make the system easier to manage, and more convenient for function expansion. Based on the division of system function, the control task is divided into various functional module. Module is be called through the running state of the system and the control instructions.Considering the plants have certain effect on soil and air humidity of the surrounding duringLiu xin et al. / Physics Procedia 33 (2012) 429 436 433u(k) 0u(k) Kpu u(k)the growth process 12-14. According the modular software design idea, the main program module of this control system software mainly includes signal collection filtering module, the true value calculation on on-site signal module, sensor calibration module, automated control module, system output module. According to the control algorithm, the control system software flow diagram of soil moisture of plant ecological park can be shown in figure 3.e(k) T kTI j 0 e(k)Fig. 3 the flowchart of humidity control in soilIn this paper, the control humidity of automatic control program is slightly lower than that of the set point, i.e., when the deviation is less than 0.05, the controller is not active, only call control function block as it is more than 0.05. By calculating the deviation, call control algorithm program of integral separation, calculate the energized time in a control cycle of the solid state relay, control opening and closing of nozzle valve. The PWM control can be achieved.According to the aforementioned control algorithm of K concentration, K + concentration use TP-PID control output as switch quantity, system has the advantages of simple structure, high reliability, easier debugging. as long as chose a correct clock pulse ,it is earlier to able to achieve satisfactory control performance, and so long as transfer the algorithm results into output pulse width, then allow to drop the potash salt, set the dropping cycle and the amount of each dropping ,the control flow graph is shown in figure 4.434 Liu xin et al. / Physics Procedia 33 (2012) 429 4363. Plant water, nutrient regulation system performance testAs the control system hardware and software design has been completed, calibrated the sensor in the room, and then transferred the whole system into trials, in the experiment, planting the potatoes as an example for testing moisture, nutrient regulation system performance. Two area plots are both 100 m2, 230 potato plants, give 1 plot a sprinkler under natural conditions, keep 2 plot irrigating in the designed control system ,After 100 days of growth, then harvest all potatoes in two areas, do a statistical analysis, the results are shown in Table 2, 3 .Table 2 represents potato consumption comparison of water and fertilizer in a lifetime of two plots, this can be seen from the table, Under the control growth, the consumption of water and fertilizer for same amount potatoes are less than the natural growth condition, therefore the design of the plant regulation system for water, nutrient has proved its energy saving function. From Figure 3, although potato plants consume less water and fertilizer under the regulation of growth, but the potato yield and quality have increased, further demonstrate that the designed control system has practicability.4. ConclusionIn this paper, Author put SIMATIC S7-300 PLC as the core controller, design the automatic control system of plant water and nutrient, apply the separation integral (P-PI ) control algorithm to automatic control the moisture and nutrient needed for plant growth, complete the system hardware and software design, set up the whole control platform, and work for a comparison experiment on the regulation of potato growth ,prove that the designed control system has the effect on reducing the water consumption and improving the production and quality of potato. The successful completion of this system has laid the foundation for automatic irrigation system research of water and fertilizer which is suitable for the development of Chinas agricultural conditions.Tab. 2 the contrast of water fertilizer dosage between different growth conditionsNo. plots (kg)Nitrogen fertilizer (kg)NH HCOPotash consumption (kg)KClThe amountof phosphate (kg) Ca(H PO )4 3 2 4 21- Natural growth 2365 14.1 3.5 15.62- Regulationof growth 1897 10.5 2.7 11.5Tab. 3 the contrast of output between different growth conditions(g)WaterNO. Production (kg) Yield per plant (kg) The average size n (mm)Average umber o ( )f Starch production plantNaturalgrowth 65.8 0.31 30 2.6 15.7Regulationof growth 97.5 0.45 43 3.5 19.1Liu xin et al. / Physics Procedia 33 (2012) 429 436 435eCon1eCon2eCon1 0eCon 2 0 Fig. 4 the flowchart of K+ concentration control in soilReferences1 Xueliang Ma, Qiheng Zhao, Hehong Tian etc., The Status Quo and Development of Global Equipment and Technology for Water-saving Irrigation J water-saving irrigation, 1999 2 4-72 Bing Zhang, Shouqi Yuan, Li Cheng, The Status Quo and Exp
温馨提示:
1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
提示  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
关于本文
本文标题:基于PLC的植物水分和养分精确调节控制系统的设计【中文3800字】
链接地址:https://www.renrendoc.com/p-10197685.html

官方联系方式

2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   
关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服 - 联系我们

网站客服QQ:2881952447     

copyright@ 2020-2024  renrendoc.com 人人文库版权所有   联系电话:400-852-1180

备案号:蜀ICP备2022000484号-2       经营许可证: 川B2-20220663       公网安备川公网安备: 51019002004831号

本站为文档C2C交易模式,即用户上传的文档直接被用户下载,本站只是中间服务平台,本站所有文档下载所得的收益归上传人(含作者)所有。人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私,请立即通知人人文库网,我们立即给予删除!