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面向对象数据库到关系数据库运算的转换 被引量:3
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作者 王学荣 曾晓勤 《计算机应用与软件》 CSCD 北大核心 2003年第9期19-25,94,共8页
本文描述了关于从面向对象数据库到关系数据库的运算转换 ,并讨论了数据描述语言和数据操纵语言运算的转换映射及其算法。这些运算包括模式定义、数据插入、数据查询、数据修改、数据删除。
关键词 面向对象数据库 关系数据库 运算转换 数据描述语言 数据查询 数据模型
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C语言中强制类型转换运算符的独特作用
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作者 谭庆 雷治军 《洛阳师范学院学报》 2006年第2期85-86,共2页
在C语言中有一个强制类型转换运算符,它为C语言中的数据类型转换带来了很大的方便,在不同类型数据之间进行赋值、运算时发挥了强大的作用.本文主要讨论了此运算符的独特作用.
关键词 强制类型转换运算 表达式 数据类型 优先级 指针 类型
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C语言教学中强制类型转换运算运用探讨 被引量:1
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作者 毛丽娜 《现代计算机》 2009年第12期135-136,146,共3页
在C语言中有一个强制类型转换运算符,它为C语言中的数据类型转换带来很大的方便,它不仅可以在不同类型数据之间进行赋值,在运算中发挥强大的作用,还可以运用在其他方面产生特殊作用。通过程序例子讨论强制类型转换运算在函数调用时实参... 在C语言中有一个强制类型转换运算符,它为C语言中的数据类型转换带来很大的方便,它不仅可以在不同类型数据之间进行赋值,在运算中发挥强大的作用,还可以运用在其他方面产生特殊作用。通过程序例子讨论强制类型转换运算在函数调用时实参与形参类型如何保持统一,计算时如何保持结果的精度及指针类型转换等几方面的运用。 展开更多
关键词 强制类型转换运算 表达式 数据类型
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A 59mW 10b 40Msample/s Pipelined ADC 被引量:1
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作者 李建 严杰锋 +4 位作者 陈俊 张剑云 郭亚炜 沈泊 汤庭鳌 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第7期1301-1308,共8页
This paper describes a 3.0V, 10b,40Msample/s analog-to-digital converter (ADC) fabricated in a 0.25μm CMOS technology. Through the sharing an amplifier between two successive pipeline stages, the converter is reali... This paper describes a 3.0V, 10b,40Msample/s analog-to-digital converter (ADC) fabricated in a 0.25μm CMOS technology. Through the sharing an amplifier between two successive pipeline stages, the converter is realized using just four amplifiers with a separate sample-and-hold block. It employs two key techniques: a high bandwidth low-power gain-boosting telescopic amplifiers technique and a low power low offset dynamic comparators technique.The ADC achieves a 8.1 effective number of bits,a maximum differential nonlinearity of a 0.85 least significant bit(LSB), and maximum integral nonlinearity of 2.2LSB for a 0.5MHz input at full sampling rate. It occupies 1.24mm^2 ,which also includes a bandgap and a voltage reference circuit and dissipates only 59mW. 展开更多
关键词 analog-to-digital converter low power OPAMP sharing technique gain-boosting technique
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An 80dB Dynamic Range ΣΔ Modulator for Low-IF GSM Receivers 被引量:1
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作者 杨培 殷秀梅 杨华中 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第2期256-261,共6页
A high-resolution,200kHz signal bandwidth,third-order single-loop single-bit ε△ modulator used in low-IF GSM receivers is presented. The modulator is implemented with fully differential switched capacitor circuits i... A high-resolution,200kHz signal bandwidth,third-order single-loop single-bit ε△ modulator used in low-IF GSM receivers is presented. The modulator is implemented with fully differential switched capacitor circuits in standard 0. 6μm 2P2M CMOS technology. The modulator uses two balanced reference voltages of ±1V,and is driven by a single 26MHz clock signal. The measurement results show that,with an oversampling ratio of 64, the modulator achieves an 80.6dB dynamic range,a 71.8dB peak SNDR,and a 73.9dB peak SNR in the signal bandwidth of 200kHz. The modulator dissipates 15mW static power from a single 5V supply. 展开更多
关键词 sigma-delta modulator analog-to-digital conversion SWITCHED-CAPACITOR operational amplifiers
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Analysis and design of high linearity current reference for current mode circuits
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作者 周明珠 朱恩 +3 位作者 王守军 王志功 韩鹏 李伟 《Journal of Southeast University(English Edition)》 EI CAS 2009年第1期18-22,共5页
A complementary metal-oxide-semiconductor transistor (CMOS) voltage-to-current(VTC)converter with high linearity for current-mode analog and digital integrated circuits is described. A high gain operational amplif... A complementary metal-oxide-semiconductor transistor (CMOS) voltage-to-current(VTC)converter with high linearity for current-mode analog and digital integrated circuits is described. A high gain operational amplifier (OPA) is utilized to form negative feedback. A proportional to absolute temperature (PTAT) current reference with transistors operated in a weak inversion is used as the bias circuit. The resistor and the OPA nonlinearity behavior are analyzed in detail. By optimizing parameters in OPA and adopting a small voltage coefficient polysilicon resistor as a linear device, a high linearity is achieved. The circuit is implemented in a standard 0. 6 μm CMOS technology. The low frequency gain of the OPA exceeds 90 dB. The test results indicate that the total harmonic distortion (THD)is 0. 000 2%. The common-mode input linearity range is 0 to 2. 6 V. Correspondingly, the output current range is 50 to 426μA. The sensitivity of the PTAT current reference to Vdd is approximately 0. 021 7. The chip consumes a power of less than 1.3 mW for a 5 V supply, and occupies an area of 0. 112 mm^2. 展开更多
关键词 linear voltage-to-current converter harmonic distortion operational amplifier PTAT current reference
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An 85mW 14-bit 150MS/s Pipelined ADC with a Merged First and Second MDAC 被引量:6
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作者 LI Weitao LI Fule +2 位作者 YANG Changyi LI Shengjing WANG Zhihua 《China Communications》 SCIE CSCD 2015年第5期14-21,共8页
A low-power 14-bit 150MS/s an- alog-to-digital converter (ADC) is present- ed for communication applications. Range scaling enables a maximal 2-Vp-p input with a single-stage opamp adopted. Opamp and capacitor shari... A low-power 14-bit 150MS/s an- alog-to-digital converter (ADC) is present- ed for communication applications. Range scaling enables a maximal 2-Vp-p input with a single-stage opamp adopted. Opamp and capacitor sharing between the first multi- plying digital-to-analog converter (MDAC) and the second one reduces the total opamp power further. The dedicated sample-and- hold amplifier (SHA) is removed to lower the power and the noise. The blind calibration of linearity errors is proposed to improve the per- formance. The prototype ADC is fabricated in a 130rim CMOS process with a 1.3-V supply voltage. The SNDR of the ADC is 71.3 dB with a 2.4 MHz input and remains 68.5 dB for a 120 MHz input. It consumes 85 roW, which includes 57 mW for the ADC core, 11 mW for the low jitter clock receiver and 17 mW for the high-speed reference buffer. 展开更多
关键词 analog-to-digital conversion LOWPOWER CALIBRATION high speed and high reso-lution pipelined analog-to-digital converter CMOS analog integrated circuits
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微电流测量方法探讨 被引量:13
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作者 汪小婷 《计量与测试技术》 2016年第12期65-66,68,共3页
本文介绍了微电流的主要的几种测量方法,包括高阻抗负反馈运放放大法、开关电容积分法、运算放大器I-F转换换法、运放差分电路I-V变换法。详细的分析了各个测量方法的电路构成和放大转换原理,同时对各测量方法的优、缺点进行和各自不同... 本文介绍了微电流的主要的几种测量方法,包括高阻抗负反馈运放放大法、开关电容积分法、运算放大器I-F转换换法、运放差分电路I-V变换法。详细的分析了各个测量方法的电路构成和放大转换原理,同时对各测量方法的优、缺点进行和各自不同的适用场合进行了比较。本文分析为研究和研制电路较简单、精度较高、成本较低、寿命较长的微电流检测仪器具有比较现实的指导作用。 展开更多
关键词 微电流检测 负反馈运放放大法 开关电容积分法 运算放大器I—F转换换法
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A Vehicle Routing Problem Based on Intelligent Batteries Transfer Management for the EV Network 被引量:2
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作者 XIA Yamei CHENG Bo 《China Communications》 SCIE CSCD 2014年第5期160-169,共10页
Batteries transfer management is one important aspect in electric vehicle(EV)network's intelligent operation management system.Batteries transfer is a special and much more complex VRP(Vehicle Routing Problem) whi... Batteries transfer management is one important aspect in electric vehicle(EV)network's intelligent operation management system.Batteries transfer is a special and much more complex VRP(Vehicle Routing Problem) which takes the multiple constraints such as dynamic multi-depots,time windows,simultaneous pickups and deliveries,distance minimization,etc.into account.We call it VRPEVB(VRP with EV Batteries).This paper,based on the intelligent management model of EV's battery power,puts forward a battery transfer algorithm for the EV network which considers the traffic congestion that changes dynamically and uses improved Ant Colony Optimization.By setting a reasonable tabv range,special update rules of the pheromone and path list memory functions,the algorithm can have a better convergence,and its feasibility is proved by the experiment in an EV's demonstration operation system. 展开更多
关键词 VRP battery power management ant colony algorithm electric vehicle network
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数学解题的转换途径
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作者 岳耀清 沈玉环 《数理化学习(高中版)》 2003年第4期2-3,共2页
在分析解答数学题时,能否根据问题的特点和解题中出现的具体情况“随机应变”,调整思路,转换途径,是我们能否简明顺利地解决问题的关键,也是思维是否具有灵活性的一个重要特征.
关键词 数学 解题 高中 教学 运算符号转换 条件形式转换 正反结论转换 结论形式转换 常规与非常规转换
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A 3V 5.88mW 13b 400kHz Sigma-Delta Modulator with 84dB Dynamic Range
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作者 李卓 杨华中 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第11期2232-2237,共6页
This paper introduces a high-revolution,200kHz signal bandwidth EA modulator for low-IF GSM receivers that adopts a 2-1 cascaded single-bit structure to achieve high linearity and stability. Our design is realized in ... This paper introduces a high-revolution,200kHz signal bandwidth EA modulator for low-IF GSM receivers that adopts a 2-1 cascaded single-bit structure to achieve high linearity and stability. Our design is realized in a standard 0.18μm CMOS process with art active area of 0.5mm× 1.1mm.The EA modulator is driven by a single 19.2MHz clock signal and dissipates 5.88mW from 3V power supply. The experimental results show that,with an oversampling ratio of 48, the modulator achieves a 84.4dB dynamic range,73.8dB peak SNDR, and 80dB peak SNR in the signal bandwidth of 200kHz. 展开更多
关键词 cascaded sigma-delta modulator analog-digital converter switched-capacitor circuits operational amplifiers CMOS analog integrated circuits
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Orthogonal transformation operation theorem of a spatial universal uniform rotating magnetic field and its application in capsule endoscopy 被引量:10
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作者 ZHANG YongShun YU ZiChun +2 位作者 YANG HuiYuan HUANG YunKui CHEN Jun 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第6期854-864,共11页
According to the anti-phase sine current superposition theorem, the orientation, the magnetic flux density, the angular speed and the rotational direction of the spatial universal rotating magnetic field (SURMF) can... According to the anti-phase sine current superposition theorem, the orientation, the magnetic flux density, the angular speed and the rotational direction of the spatial universal rotating magnetic field (SURMF) can be controlled within the tri-axial orthogonal square Helmholtz coils (TOSHC). Nevertheless, three coupling direction angles of the normal vector of the SURMF in the Descartes coordinate system cannot be separately controlled, thus the adjustment of the orientation of the SURMF is difficult and the flexibility of the robotic posture control is restricted. For the dimension reduction and the decoupling of control variables, the orthogonal transformation operation theorem of the SURMF is proposed based on two independent rotation angular variables, which employs azimuth and altitude angles as two variables of the three-phase sine current superposition formula derived by the orthogonal rotation inverse transformation. Then the unique control rules of the orientation and the rotational direction of the SURMF are generalized in each spatial quadrant, thus the scanning of the normal vector of the SURMF along the horizontal or vertical direction can be achieved through changing only one variable, which simplifies the control process of the orientation of the SURMF greatly. To validate its feasibility and maneuverability, experiments were conducted in the animal intestine utilizing the innovative dual hemisphere capsule robot (DHCR) with active and passive modes. It was demonstrated that the posture adjustment and the steering rolling locomotion of the DHCR can be realized through single variable control, thus the orthogonal transformation operation theorem makes the control of the orientation of the SURMF convenient and flexible significantly. This breakthrough will lay a foundation for the human-machine interaction control of the SURMF. 展开更多
关键词 dual hemisphere capsule robot (DHCR) spatial universal rotating magnetic field (SURMF) orthogonal transformation operation variable decoupling
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