关键词： GPU   Memory optimization   Multi-thread   Pthread   Register   Shared memory   Time-domain least-squares reverse time migration  

摘要： Least-squares reverse time migration (LSRTM) can accurately obtain images of subsurface ***, its application to actual data can be challenging owing to the large amount of calculation ***, a parallel acceleration strategy that combines Pthread standard with multithread-driven multi-graphics-processing-unit (multi-GPU) is *** method decomposes computing tasks in common-shot gather domain with real-time update of data through multi-GPU parallel *** GPU memory optimization method is used to invoke high-speed memory, such as shared memory and registers, to increase the computational efficiency of wave field ***, acceleration of 2D time-domain LSRTM is *** method was tested using the Marmousi2 truncation and Marmousi synthetic *** results showed that the proposed method is applicable to different types of *** the increase in data scale, the acceleration efficiency can gradually approximate linear acceleration, and is enhanced with small data synchronization delay. Copyright ©2019 Geophysical Prospecting for Petroleum. All rights reserved.

关键词： Sun: atmosphere   Sun: chromosphere   Sun: corona   Sun: flares   Sun: transition region  

摘要： Understanding the dynamics of the chromosphere is crucial to understanding energy transport across the solar atmosphere. The chromosphere is optically thick at many wavelengths and described by non-local thermodynamic equilibrium (NLTE), making it difficult to interpret observations. Furthermore, there is considerable evidence that the atmosphere is filamented, and that current instruments do not resolve small-scale features. In flares, it is likely that multithreaded models are required to describe the heating. The combination of NLTE effects and multithreaded modeling requires computationally demanding calculations, which has motivated the development of a model that can efficiently treat both. We describe the implementation of a solver in a hydrodynamic code for the hydrogen level populations that approximates the NLTE solutions. We derive an accurate electron density across the atmosphere that includes the effects of nonequilibrium ionization for helium and metals. We show the effects on hydrodynamic simulations, which are used to synthesize light curves using a postprocessing radiative transfer code. We demonstrate the utility of this model on IRIS observations of a small flare. We show that the Doppler shifts in Mg II, C II, and O I can be explained with a multithreaded model of loops subjected to electron beam heating, so long as NLTE effects are treated. The intensities, however, do not match the observed values very well, which is due to assumptions about the initial atmosphere. We briefly show how altering the initial atmosphere can drastically alter line profiles and derived quantities and suggest that it should be tuned to preflare observations.

关键词： MOSFET器件   低功耗   漏电性能  

摘要： 针对0.13μm工艺常规MOSFET器件的制备流程进行了分析,提出了低功耗工艺改善方法,并针对优化工艺条件下的器件进行TCAD仿真,设计并进行了完整的DOE实验及样品性能测试。测试结果表明,通过调整轻掺杂漏区(LDD)的离子注入条件,冠状离子注入区的角度、浓度以及沟道阀值电压离子注入区浓度等一系列方法,实现了0.13μm工艺1.5 V MOSFET器件关断条件下漏电流低于1 pA/μm。

关键词： LoRa   低功耗   事件驱动算法   时间同步   实时监测  

摘要： LoRa作为低功耗广域网数据传输技术之一,被广泛应用于工业、农业等领域之中,它与传统的无线传感网络技术相比有着功耗低、距离远、抗干扰性强等优势。针对传统的工业无线监测存在的传输距离近、功耗高等问题,该文设计并实现了基于LoRa的工业温度无线采集系统。该系统可以实现对工业环境中监测区域的温度参数的采集和处理,并上传至服务器以供监控人员实时监测。系统采用了基于低功耗、低碰撞的星型无线网络结构的类蜂窝网络结构,采用基于事件驱动的节点数据预处理算法对传感器数据进行采集和发送。实验结果表明该系统具有功耗低、可扩展性强、覆盖范围广、传输稳定的特点,能够满足工业信息采集和监测的需求,可推广使用。

关键词： 爬虫   多线程   布隆过滤器   Redis  

摘要： 针对单线程的局限性,设计一种基于Java多线程技术的并发网络爬虫,使用布隆过滤器对爬取过消息队列进行过滤,结合Redis缓存技术,提高爬虫效率,对知乎用户信息的进行抓取,实验结果表明,多线程爬虫能够极大地提高爬虫的效率,从而实现快速、高效的信息采集。

关键词： MSP430单片机   DS1302   指纹传感器   低功耗  

摘要： 设计了一款低功耗便携式的指纹考勤机。采用MSP430F149作为16位低功耗器件的主控制器,采用低功耗双电源DS1302时钟芯片提供系统时间,基于光学原理的指纹传感器实现指纹的读取,并通过软件编程将其与预先建立的指纹数据库进行比对,最终实现考勤系统的准确性及唯一性,并由LCD12864实时显示当前信息,同时,串口助手用于实现上位机考勤信息的记录。硬件测试表明,该设计具有功耗低、操作便捷、实用性强的特点,应用前景广。

关键词： 双电压   高速电磁铁   低功耗   脉宽调制  

摘要： 针对提升电液控制系统动态和稳态性能的需求,提出一种双电压合成信号脉宽调制的低功耗高速电磁铁驱动电路。与常见的双电源切换电路不同,该电路通过单稳态触发器电路、反相输入求和电路、反相比例运算电路合成一个双电压信号,与高频三角波电路比较产生一个双占空比的脉宽调制信号,最后经功率放大级输出,实现初始阶段100%占空比脉宽调制信号使电磁铁线圈电流急速上升驱动衔铁高速运动,运动结束后又以10%占空比实现低功耗保持,避免了双电源切换电路设计的复杂性和实时性问题。基于上述原理,建立高速电磁铁及驱动电路的理论模型,仿真分析电磁铁的动态和稳态性能,并结合原型样机进行实验验证。研究结果表明:与典型恒定电压或恒定占空比控制方式相比,性能明显提高,该驱动电路作用下的电磁铁在2.5mm行程内开启时间为10ms,关闭时间为22ms,稳态功耗为0.3W,可更好地满足低功耗高速电磁铁的驱动要求。

关键词： 基准电流   基准电压   CMOS   超低功耗   亚阈值  

摘要： 设计了一种超低功耗全CMOS基准电路:既能产生1 nA的基准电流又能产生560 mV的基准电压。通过亚阈值设计方法有效降低了基准电路的功耗;采用工作在深线性区的MOS管取代了传统基准电路中的电阻,大大降低了面积;采用共源共栅电流镜提高了电源抑制比。利用SMIC 55 nm的工艺,使用Cadence Spectre对电路进行了仿真。仿真结果表明,在-40℃到110℃的温度范围内,基准电流的温漂系数为0.28%/℃,基准电压的温漂系数为24 ppm/℃;在0.9 V到2 V电源电压范围内,基准电流的电源电压调整率为2.6%/V,基准电压的电源电压调整率为0.48%/V;在100 Hz处,基准电流的PRSS为-34 dB,基准电压的PRSS为-50 dB。功耗为6 nW,芯片版图面积仅0.000 42 mm2。

关键词： Python   网络爬虫   Flickr   多线程   图片  

摘要： 如今的互联网已然进入大数据时代,网络上有数以百计的图片,图片网络爬虫可以通过既定的规则自动地抓取互联网上的图片并下载至本地存储,通过对国内外各大图片网站的调查研究,决定以国外网站Flickr为对象通过Python程序设计语言来实现获取高质量的,准确的,完整的图片和信息。最终成功实现了对Flickr网站上的图片按照检索的字段,批量爬取图片信息并下载图片的程序。