关键词： Lora技术   供热监控   嵌入式模块   RSSI定位   低功耗   物联网   数据采集   单片机  

摘要： 城市供热系统布局环境复杂多样,终端变量参数数据信号采集及传输受到很多环境噪声及不规则建筑物的干扰,导致传统城市供热管网监控系统存在数据采集效率低下、定位误差大和丢包率严重的问题。如今,物联网技术的发展如火如荼,劳拉(Lora)技术以其低功耗、远距离、低成本及抗干扰能力强等优异特性而广受企业青睐,已成为最具发展前景的广域网通信技术之一。创新性地引入Lora无线传播技术,并与接收信号强度指示(RSSI)定位技术相结合,运用嵌入式模块F8L10T及网关设计了一种新型的城市供热管网监控系统。系统在改善信号采集及传输质量的同时提升了定位精度。试验结果表明,该系统实现了定时数据采集和监控报警的目的。

关键词： Dynamic random access storage  

摘要： Tracing the evolution of the five-minute rule to help identify imminent changes in the design of data management engines.

关键词： CPU scheduling   Tail latency   Multi-threaded applications   Linux CFS scheduler  

摘要： Large-scale interactive Web services break a user's request to many sub-requests and send them to a large number of independent servers so as to consult multi-terabyte datasets instantaneously. Service responsiveness hinges on the slowest server, making the tail of the latency distribution of individual servers a matter of great concern. A large number of latency-sensitive applications hosted on individual servers use thread-driven concurrency model wherein a thread is spawned for each user connection. Threaded applications rely on the operating system CPU scheduler for determining the order of thread execution. Our experiments show that the default Linux scheduler (CFS) idiosyncrasies result in LCFS (Last Come First Served) scheduling of threads belonging to the same application. On the other hand, studies have shown that FCFS (First Come First Served) scheduling yields the lowest response time variability and tail latency, making the default scheduler of Linux a source of long tail latency for multi-threaded applications. In this paper, we present CTS, an operating system CPU scheduler to trim the tail of the latency distribution for latency-sensitive multi-threaded applications while maintaining the key characteristics of the default Linux scheduler (e.g., fairness). By adding new data structures to the Linux kernel, CTS tracks threads belonging to an application in a timely manner and schedules them in FCFS manner, mitigating the tail latency. To keep the existing features of the default Linux scheduler intact, CTS keeps CFS responsible for system-wide load balancing and core level process scheduling;CTS merely schedules threads of the CFS chosen process in FCFS order, ensuring tail latency mitigation without sacrificing the default Linux scheduler properties. Experiments with a prototype implementation of CTS in the Linux kernel demonstrate that CTS significantly outperforms the Linux default scheduler. For example, CTS mitigates the tail latency of a Null RPC

摘要： For many next generation-sequencing pipelines, the most computationally intensive step is the alignment of reads to a reference sequence. As a result, alignment software such as the Burrows-Wheeler Aligner is optimized for speed and is often executed in parallel on the cloud. However, there are other less demanding steps that can also be optimized to significantly increase the speed especially when using many threads. We demonstrate this using a unique molecular identifier RNA-sequencing pipeline consisting of 3 steps: split, align, and merge. Optimization of all three steps yields a 40% increase in speed when executed using a single thread. However, when executed using 16 threads, we observe a 4-fold improvement over the original parallel implementation and more than an 8-fold improvement over the original single-threaded implementation. In contrast, optimizing only the alignment step results in just a 13% improvement over the original parallel workflow using 16 threads.

关键词： 脉冲宽度调制   亚阈值泄漏   高效率转换  

摘要： 设计了一种应用于能量收集领域的低功耗、超低电压DC-DC升压转换器。研究了转换器工作频率与功率和效率的关系,通过选择合适的脉冲宽度调制(PWM)频率来提高输出功率。通过适当提升转换器开关功率管的栅极电压,减小了晶体管的泄露电流,从而提高了输出电压。基于CMOS 65nm工艺进行设计。仿真结果表明,提出的方案能提高弱能量转换效率。当输入电压为100mV时,最大输出电压为1 000mV。DC-DC升压转换器的输出功率为3.08μW,转换器控制单元的功耗为697nW,转换效率达到57.3%。

关键词： 深度卷积神经网络   低功耗   ISSCC   嵌入式系统   意法半导体   SOI工艺   SoC   网络拓扑  

摘要： 前年的ISSCC 2017大会上,意法半导体做过一个题为“针对智能嵌入式系统、采用28nm FD-SOI工艺的2.9TOPS/W深度卷积神经网络SoC”(A 2.9 TOPS/W Deep Convolutional Neural Network SoC in FD-SOI 28nm for Intelligent Embedded Systems)的演讲。演讲中的这颗SoC应用,当然如其名就是卷积神经网络(CNN),而宣传重点在高效的存储层级,适用于不同深度卷积神经网络拓扑的弹性,输入输出能力,还有与主流的深度学习工具做整合。

关键词： 蓝牙通信   心电   信号预处理   实时监测   AD8232  

摘要： 针对便携式心脏健康监护需求的增多,设计了一种基于低功耗、双模蓝牙通信的心电监护系统。通过低功耗、双模蓝牙模组HM-13及制定的数据传输协议,实现系统上位机与下位机间的通信;利用双手腕部的可重复电极,实现心电信号的采集;采用AD8232设计硬件低通滤波与放大电路,STM32微处理器进行软件滤波与下位机系统设计,并基于LabVIEW开发信号预处理程序与上位机监测界面。其中,信号预处理过程主要包括低通滤波、工频陷波与经验模态分解、R波检测与心率计算等。经实验验证,该设计能够准确、实时监测人体心电图与心率等特征,实现了便携式心脏健康监护功能。

关键词： 本安电源   闸流   霍尔电流传感器   保护电路  

摘要： 常规本安电路采用限流电阻或截流限流本安保护电源,发热严重,效率低。文中采用了霍尔电流传感器和闸流保护技术设计本安电源电路,利用单稳延时设置过流保护后的自动恢复时间。根据负载的差异,该本安电源电路可设置闸流阈,对设计电路进行了计算和分析,测试结果表明达到了本安标准要求,并具有内阻小、保护快和效率高的特点。

关键词： 低功耗   广域物联网   LoRaWAN   云平台   网络服务器   智慧旅游  

摘要： 针对传统通信技术信号覆盖不足、功耗高、运行成本高等问题,面向广域物联网,基于LoRaWAN协议,设计并实现了一个广域物联网云平台。与传统云平台不同,低功耗广域物联网云平台添加了LoRa架构中的网络服务器,网络服务器主要负责管理与控制由网关和节点组成的LoRa网络。在支持高并发终端设备的情况下,该平台达到了快速、便捷、可靠地采集终端节点数据的目的,大大降低了物联网应用搭建的成本及难度,同时也提高了物联网应用的开发效率。该平台最终通过了测试并实现了智慧旅游监测系统,验证了广域物联网云平台服务功能的有效性、可靠性及稳定性。