Auto CAD 2014中文版从入门到精通，本书既可以作为了解AutoCAD各项功能和最新特性的应用指南，又可以作为提高用户设计和创新能力的指导。
标签： autocad
上传时间： 2022-04-07
上传用户：
CAD打开时候提示找不到字体GBCBIG.SHX，可以使用这个字体。使用方法：下载后解压到AUTO CAD安装目录下的FONTS文件夹内。
上传时间： 2013-07-31
上传用户：集美慧
LT8900是LDT公司生产的一款低成本，高集成度的2.4GHZ的无线收发芯片，片上集成发射机，接收机，频率综合器，GFSK调制解调器。发射机支持功率可调，接收机采用数字扩展通信机制，在复杂环境和强干扰条件下，可以达到优良的收发性能。外围电路简单，只需搭配MCU以及少数外围被动器件。LT8900传输GFSK信号，发射功率约为2dBm，最大可以到6dBm。接收机采用低中频结构，接收灵敏度可以达到-87dBm。数字信道能量检测可以随时监控信道质量。 片上的发射接收FIFO寄存器可以和MCU进行通信，存储数据，然后以1Mbps数据率在空中传输。它内置了CRC，FEC，auto-ack和重传机制，可以大大简化系统设计并优化性能。 数字基带支持4线SPI和2线I2C接口，此外还有Reset，Pkt_flag, Fifo_flag三个数字接口。 为了提高电池使用寿命，芯片在各个环节都降低功耗，芯片最低工作电压可以到1.9V，在保持寄存器值条件下，最低电流为1uA。 芯片有QFN24 4*4mm和SSOP16封装，都符合RoHS标准。
上传时间： 2013-04-24
上传用户：kirivir
·ITU-T G.729的一个实现例子(包括附录b的vod检测等功能)-ITU-T g.729 example, include VOD detect of reference B, etc.文件列表(点击判断是否您需要的文件): g729b_v14 .........\acelp_co.c .........\basic_op.c .....
上传时间： 2013-05-20
上传用户：Garfield
One of the strengths of Synplify is the Finite State Machine compiler. This is a powerfulfeature that not only has the ability to automatically detect state machines in the sourcecode, and implement them with either sequential, gray, or one-hot encoding. But alsoperform a reachability analysis to determine all the states that could possibly bereached, and optimize away all states and transition logic that can not be reached.Thus, producing a highly optimal final implementation of the state machine.
标签： Synplicity Machine Verilog Design
上传时间： 2013-10-23
上传用户：司令部正军级
为解决电致变色器件的颜色变化受外界环境颜色控制的问题，设计了一种基于单片机的便携式颜色自适应识别电路。与传统颜色识别电路相比较，该电路利用数字式的颜色传感器来获取外界环境颜色，产生的数字颜色信号易于单片机进行处理。在电路中，下位机部分主要负责获取电致变色器件变色参数及控制电致变色器件的颜色变化;而上位机部分主要负责把下位机获取的电致变色器件变色参数进行电压到颜色的曲线拟合，并通过蓝牙通信把拟合曲线参数传递给下位机。结果表明，该电路能自动根据环境颜色提供-4~4 V范围步进为0.1 V的电压来驱动电致变色器件的颜色显示，与传统的颜色识别电路设计相比，识别的精度和速度都得到了明显改善。 Abstract: In this paper， a portable adaptive circuit for color identification(PACCI) based on MCU was designed. Compared to the traditional color identification circuit， the PACCI adopts digital sensor to detect the color data from external environment and further generate digital color data， which can be processed easily by MCU. In PACCI， the slave is mainly responsible for detecting the color parameters of the corresponding elcreochromic device and further driving it. For the master， which is mainly responsible for the color curve fitting based on the parameters of the electrochromic device， and transmits the fitting parameters to the slave through the bluetooth device. The results show that the PACCI can provide the basis voltage range from -4V to 4V automatically based on the colors of external environment with step as 0.1V to drive the corresponding electrochromic device. Compared to the traditional color recognition circuit， the recognition accuracy and speed of PACCI have been improved significantly.
上传时间： 2013-11-09
上传用户：franktu
在航电系统维护过程中，为解决定位故障的效率和降低维修成本等问题，提出了基于ICD（Interface Control Document，接口控制文件）的1553B总线的信息监控系统模型。该系统运用数据采集卡对总线中传输的信号有无失真、偏差等电气特性进行检测，并使用1553B通讯卡通过测控软件LabWindows/CVI编程与ICD数据库的动态链接，实现总线信息的解析和故障的判断。与传统的维护过程相比，这种模型能够从信号的电气特性以及信息的解析等全方位的去检测判断故障的来源，并且能够广泛在其他1553B总线系统内扩展应用。验证表明该监控系统可以对总线信息进行快速有效地监测分析，能满足应用需求。 Abstract: In the process of avionics system maintenance， to solve the problems such as improving the efficiency of fast orientation to troubles and reducing maintenance cost， system of 1553B bus information monitor model based on ICD was proposed. The system observed whether the data which transmitted on the bus appear distortion and deviation by using data acquisition card. And using 1553B communication card programming of the measure software LabWindows/CVI and the dynamic linking of ICD database， message analysis and fault estimation could be realized. Compared with traditional maintenance， this model can all-dimensionally detect and analyze the source of faults from both electrical characteristics of the signal and message analysis， and it can be widely applied in the other 1553B system. Experiment shown that this monitor system can effectively detect and analyze the bus message and can meet the application requirements.
上传时间： 2013-11-23
上传用户：18752787361
在深入了解Flash存储器的基础上，采用单片机自动检测存储器无效块。主要通过读取每一块的第1、第2页内容，判断该块的好坏，并给出具体的实现过程，以及部分关键的电路原理图和C语言程序代码。该设计最终实现单片机自动检测Flash坏块的功能，并通过读取ID号检测Flash的性能，同时该设计能够存储和读取1GB数据。 Abstract: On the basis of in-depth understanding the Flash chips，this paper designs a new program which using the SCM to detect the invalid block.Mainly through reading the data of the first and second page to detect the invalid block.Specific implementation procedure was given,and the key circuit schematic diagram and C language program code was introduced.This design achieved the function of using the MCU checks the invalid block finally，and increased the function by reading the ID number of Flash to get the performance of the memory.And the design also can write and read1GB data
上传时间： 2013-10-25
上传用户：taozhihua1314
针对盘山路存在的转弯盲区，即在转弯时司机无法得知弯路对面是否有车辆通过，设计一种基于C8051F310的山路转弯预防警示系统。该系统利用一阶滤波算法检测山路转弯时是否有车辆通过。运用该算法可增强系统检测的实时性，提高检测机动车辆的灵敏度，同时大大减少环境温度对检测的干扰。试验表明该系统能够正确指示出在山路转弯时是否有车辆通过，目前该系统已安装在盘山路上，可大大减少事故的发生率。 Abstract: Aiming at passing hilly road，there is a turn blind spot.Motormen usually do not know if the passing of vehicles pass the road.So a system of defending accident on hilly road is designed,which is based on MCU C8051F310.The sys-tem uses the first-order filter algorithm to detect whether there are passing vehicles.This algorithm enhances the real-time detection and improves the sensitivity of detection vehicles.Meanwhile,it reduces the detection interference of environmen-tal temperature.The experimental results show that this system can exactly indicate if there are passing vehicles.At present,the system has been successfully applied to hilly road.The system can greatly decrease accident.
上传时间： 2013-10-10
上传用户：归海惜雪
为满足矿井安全生产要求，介绍了一种以AT89C51单片机为主控器，对环境空气的温度、有毒易燃气体的浓度等进行检测的监控系统。该系统配合外围电路能实现对上述环境指标的控制并存储相关数据与上位PC机通信。它采用硬件抗干扰和软件抗干扰技术，以确保整个系统工作的准确性。 Abstract: In order to meet the needs of mine produce safety，a kind of intellignet mine ambient monotoring and control system based on AT89C51 is introduced.This system can detect the temperature of ambient of mine，the density of poisonous inflammable gas,combined external circuit.With its function part， this system can change above-mentioned elements.
上传时间： 2013-11-10
上传用户：wendy15
