基于Raspberry Pi的电梯彩屏显示系统设计

本文针对多媒体彩屏电梯显示的需求,在ARM内核树莓派平台和单片机接口板双处理器架构的硬件支持下,利用485/CAN总线传输技术、Linux应用编程、Qt5用户界面编程,提出并实现了一种双处理器架构的电梯彩屏显示系统。此彩屏显示系统与传统显示系统相比,界面更美观,功能更丰富,且具有低成本、高稳定性等特点。实际测试结果表明,此电梯彩屏显示系统设计的可行性和有效性。     

一种基于条件Pi演算的组合服务柔性演化模型

组合服务应当具有适应所处环境和商业规则不断变化的能力。现有的服务组合语言和执行机制缺乏应对动态变化所需的可变性和适应性。尽管已有很多扩展,但是组合服务的动态适应正确性还缺乏保障。提出了一种基于条件Pi演算的组合服务柔性演化机制。通过增加归属操作符和条件控制符对经典Pi演算进行扩展,使之与事件-条件-动作模式更好地结合起来,从而提出了一种描述组合服务流程的方法。从分析组合服务各种变化的场景出发,提出了11种基本的变化场景及其不同的柔性演化模式,对每种模式进行了形式化描述和分析。该方法能够保证组合服务的可变性和适应正确性。     

基于树莓派的环境监控小车设计与实现

介绍了智能小车在环境监测和远程视频监控中的应用。基于树莓派核心板,通过温湿度传感器获取环境温湿度数据,高清摄像头获取实时的视频图像数据,然后采用WiFi方式将视频图像数据传送到手机终端,手机终端通过蓝牙方式发出控制指令。小车接收指令后,通过直流电机芯片TB6612FNG驱动小车运动,达到远程的可移动式环境监控的目的。系统具有自动循迹和手动控制功能,自动循迹可以在设定路线进行巡线数据采集。实验结果表明,智能小车样机较好地实现了预期的环境数据和视频图像采集功能,实现了远程环境监控。     

Radial structure of low pressure rf capacitive discharges

This paper studies the glow intensity distribution of the discharge plasma against the tube radius and reports the radial profiles of electron temperature and plasma concentration in the rf capacitive discharge registered with a Langmuir probe. An abrupt increase of electron temperature and glow intensity near the tube wall in the weak-current α-mode of the rf capacitive discharge is revealed, the radial distribution of plasma concentration and ion flow to the electrodes possessing a maximum near the radial sheath boundary. In the γ-mode of the rf capacitive discharge the electron temperature decrease in the total plasma volume leads to an electric field weakening and the peak of the glow intensity near the tube wall vanishes. The radial sheath thickness in the α-mode of the rf capacitive discharge obtained with 2D simulation experiences pulsations during the rf field period, the changing radial electric field heating electrons and increasing the plasma concentration near the boundary of the radial sheath.     

Self-organized dye particles: Role of dewetting process in molecular ordering

Self-organized rhodamine 6G particles prepared by wetting/dewetting process of an ethanol solution on a hydrophilic glass surface exhibited fluorescence without quenching, showing a sharp linewidth of 2 nm with a large redshift, which indicates an existence of dye aggregates, similar to J aggregates, inside the particle. Polarized evanescent field excitation showed that the dye molecule's transition moment along the π-conjugation was oriented unidirectionally within particles and parallel to the substrate surface. This deduced dye orientation showed correlation between adjacent, however separated, particles, and pointed roughly 45° off the dewetting direction. In contrast, another π-conjugated NK1420 dye, J aggregates of which grow easily from an oversaturated solution, yielded particles with constituent dyes oriented along the dewetting direction preferably, still indicating the effect of self-organization, however based on a different mechanism.     

基于Movidius神经计算棒的行人检测方法

Movidius神经计算棒是基于USB模式的深度学习推理工具和独立的人工智能加速器，为广泛的移动和嵌入式视觉设备提供专用深度神经网络加速功能。针对深度学习的嵌入式应用，实现了一种基于Movidius神经计算棒的近实时行人目标检测方法。首先，通过改进RefineDet目标检测网络结构使模型大小和计算适应嵌入式设备的要求；然后，在行人检测数据集上对模型进行重训练，并部署于搭载Movidius神经计算棒的树莓派上；最后，在实际环境中对模型进行测试，算法达到了平均每秒4帧的处理速度。实验结果表明，基于Movidius神经计算棒，在计算资源紧张的树莓派上可完成近实时的行人检测任务。     

Efficient resource management in the cloud: From simulation to experimental validation using a low-cost Raspberry Pi testbed

Within the context of cloud computing, efficient resource management is of great importance as it can result in higher scalability and significant energy and cost reductions over time. Because of the high complexity and costs of cloud environments, however, newly developed resource allocation strategies are often only validated by means of simulations, for example, by using CloudSim or custom-developed simulation tools. This article describes a general approach for the validation of cloud resource allocation strategies, illustrating the importance of experimental validation on physical testbeds. Furthermore, the design and implementation of Raspberry Pi as a Service (RPiaaS), a low-cost embedded testbed built using Raspberry Pi nodes, is presented. RPiaaS aims to facilitate the step from simulations toward experimental evaluations on larger cloud testbeds and is designed using a microservice architecture, where experiments and all required management services are running inside containers. The performance of the RPiaaS testbed is evaluated using several benchmark experiments. The obtained results not only illustrate that the overhead of both using containers and running the required RPiaaS services is minimal but also provide useful insights for scaling up experiments between the Raspberry Pi testbed and a larger more traditional cloud testbed. The introduced validation approach is then illustrated using a case study focusing on the allocation of hierarchically structured tenant data. The results obtained through simulations are compared to the experimental results. The RPiaaS testbed proved to be a very useful tool for the initial experimental validation before moving the experiments to a large-scale testbed.     

Osmotic Dehydrated Raspberries: Changes in Physical Aspects and Bioactive Compounds

Raspberries are very labile fruits that have a short postharvest life; therefore, there is a need to develop alternative storage and processing methods for extending their shelf-life. The effect of wet (WI) and dry (DI) sucrose infusions (a_w = 0.85) on color and bioactive compounds of raspberries has been studied. Additives were included: citric acid, sodium bisulfite, or both. Moisture content decreased from 85% (w/w) for control fruit to approximately 51% (w/w) for infused samples. The shrinkage of fruits was approximately 27% and 46% after WI and DI, respectively. No major color changes occurred, except for WI-bisulfite treatment. Although the total polyphenols and anthocyanin content were significantly reduced in fruits during osmotic dehydration, mainly due to the dilution effect to the medium, 100 g serving of processed raspberries would supply, in some cases, over 50% of polyphenols provided by a glass of wine. The proposed infusion dehydration methods may be considered an alternative to produce shelf-stable products based on raspberries, with an improved quality in terms of appearance.     

Cathodic shift and improved photocurrent performance of cost-effective Fe2O3 photoanodes

We successfully fabricated cost-effective and efficient pulse electrodeposited Fe₂O₃ photoanodes for PEC water splitting application. Surface modifications of Fe₂O₃ by oxygen evolution catalysts like cobalt phosphate (Co–Pi), a monoclinic BiVO₄ or both showed cathodic/anodic shift in photocurrent with significantly improved photo-response.