基于飞思卡尔i.MX31的Standalone开发平台设计

针对如何精确取得基于飞思卡尔i.MX31硬件平台下WMA(Windows Media Audio)Decoder的运行性能,提高其执行效率这一课题,搭建了Standalone开发平台。搭建该平台的关键是如何配置i.MX31中的MMU(Memory Management Unit)。我们目前采用段存储块机制实现MMU。通过对在该平台下WMA Decoder实验数据的分析,已经精确地取得了项目的性能,而且运行效率也提高了29%。

Customized Standalone GIS-Based Tool for Ground Water Quality Assessment: Gaza Strip as a Case Study

Employing the full versions of GIS software with its numerous functions to manage case-specific applications is becoming inconvenient for many reasons. A convenient solution that is spreading worldwide to solve this problem is to develop customized tools that use the same GIS concept to meet specific applications. The water resource department in Gaza strip has been facing technical and financial difficulties in using the full GIS versions in managing groundwater resources. Thus, the objective of this paper was to develop a customized standalone GIS-Based ground water quality assessment tool (GWQAT) to be used by the water resources management department in Gaza strip. GWQAT was developed using Microsoft visual basic programming language, a regression mathematical model, map objects, and map files generated from ESRI ARC Info. GWQAT was designed to achieve many functions such as mapping, map overlaying, buffering, charting, soil hydro-geological profiling, and predicting future groundwater quality parameters variations. The simplicity and validity of GWQAT was demonstrated by its application on the groundwater quality parameters in Gaza strip wells with emphasis on chloride concentration.

Coordinated control between a grid forming inverter and grid following inverters suppling power in a standalone microgrid

Battery energy storage systems,fuel cells,and photovoltaic generators are being adopted in distribution networks to achieve CO;emission reduction.These power sources require inverters to connect to AC networks.However,sub-networks,such as a microgrids containing inverter power sources,may be disconnected from the utility network and operated in a standalone mode during extended blackouts.This study focuses on a standalone microgrid supplied by inverter power sources without a synchronous generator and proposes a new microgrid inverter control.In this inverter control,a single grid forming inverter is operated as a master power source to determine frequency and voltage,and other inverters,called grid following inverters,are operated as subordinate power sources with active and reactive power control.The necessary functions in the energy management system are examined,and the coordinated operation of all inverters in the microgrid is demonstrated via simulation.

Optimum Sizing and Economic Analysis of Standalone PV System with a Small Size Grinding Mill

This work presents the results of the characterization of a standalone photovoltaic system for the electrification of a household located in rural area in the western region of Cameroon: Nziih-Bafou in Dschang (5.35°N, 10.05°E and 1900 m). In order to cope with the maintenance charges and reduce the investment cost, a small mill was added to the appliances of the household for income generation. The assessment of the energy demand was made by taking into account the reactive energy due to the heavy consumption of energy by the mill’s motor, especially during ignition. The sizing of all the system’s components was carried out with the prospect of determining an optimum design in accordance with daily electricity demand, site irradiance profile and climatic conditions. In this context, tilt angles applicable to the PV structure and that allow to receive the maximum irradiance as a function of the periods of the year were determined using the Hay model. This approach provides the system with incident irradiance greater than or at the limit equal to that received by a horizontal surface on the same site compared to the case of a single tilt angle where the irradiance on the inclined plane is often lower than that on the horizontal. The economic analysis of the PV system showed an initial cost of $4448 and the Life Cost Cycle amounted to $24,495. This amount corresponds to a present cost per kilowatt hour of $0.44. The Net Present Value (NPV) of the project ($7793) over its lifetime (20 years) shows a payback period of less than 4 years.

VE464 Standalone DPG系统在VSP测井中的应用

VE464和428XL仪器是一体化设计的,为了兼容428XL以外的其它地震采集系统,Sercel公司开发了Standa-lone DPG系统。本文结合VSP测井实践,介绍了Standalone DPG系统的工作模式、构建方式以及在VSP测井中应用的一般操作步骤。

Parallel inverter control using different conventional control methods and an improved virtual oscillator control method in a standalone microgrid

Partly because of advances in power electronic converters,the share of renewable energy in power generation is steadily increasing.The main medium of interface for integrating renewable energy sources to the utility grid is the power electronic inverter.Virtual oscillator control(VOC)is a time-domain approach for controlling parallel inverters in a standalone microgrid(MG).The concept is to simulate nonlinear deadzone oscillator dynamics in a system of invert-ers to ensure a stable AC MG in the absence of communication.VOC is a time-domain and self-synchronizing control-ler that simply requires the measurement of filter current,whereas traditional droop control and the virtual synchro-nous machine(VSM)require low pass filters for active and reactive power calculations.In this work,a particle swarm optimization(PSO)-based VOC method(VOC-PSO)is proposed,in which the parameters of the VOC are designed using the PSO algorithm.The system performance using droop,VSM,VOC,and VOC-PSO controllers are investigated using MATLAB and Opal-RT real-time digital simulator platforms.The results show that the proposed VOC-PSO gives improved performance over other control strategies.The efficacy of the proposed VOC-PSO control method is also demonstrated by the experimental results.

构巢曲霉与30种丝状子囊菌的基因组比较

为探讨丝状子囊菌的序列同源性,文章利用公开发表的真菌基因组序列构建本地基因组数据库,设置E值统计阈值为0.1,将构巢曲霉(Aspergillus nidulans)基因组的10560个注释基因分别与30种丝状子囊菌基因组比较。结果表明,同源匹配基因数量的多少可反映子囊菌之间的进化关系。构巢曲霉基因组的924个基因与这30种子囊菌基因组同时存在匹配序列,其中E值在10-5～0.1、10-30～10-5、10-100～10-30、0～10-100范围内都存在匹配序列的基因分别为6个、3个、6个和6个。ClustalX多序列比对分析显示,E值10-5～0.1的6组序列和E值10-30～10-5的3组序列均显示变异性过大而E值0～10-100的6组序列过于保守,E值介于10-100～10-30之间的6组同源序列可用于本研究的31种子囊菌系统学分析。

异构环境下Spark动态资源调度策略研究

针对Spark未考虑异构集群节点间的性能差异,导致多作业场景下节点负载不均衡、作业执行效率低的问题,提出一种基于异构集群节点负载的Spark动态资源调度策略。根据节点静态负载和运行时的动态负载信息建立异构集群节点负载评价指标,获取集群运行时节点的实时负载;改进Spark默认资源管理器Standalone在资源分配时的节点排序规则;最终实现基于异构集群节点负载的动态资源调度策略。实验结果表明,与默认调度策略相比,该策略评价指标适用性更好,有效缓解了集群的负载失衡问题,提高了作业执行效率。

简析NB-IOT关键技术特性及行业应用

根据传输速率的不同,可将物联网业务进行高、中、低速的区分。本文分析NB-Io T的四大技术优势及关键技术特性,探讨NB-Io T"四大"技术的行业应用与前景瞻望。

Optimisation of Hybrid Energy System Production Parameters for Electricity Power Generation in Nigeria

Solar and wind energy are two of the most viable and sustainable sources of energy due to the tendency of renewal. The power generating supplies in Nigeria appear unreliable, rapidly diminishing and expensive. Researches are sparse on operating both energy sources alongside fossil fuel for power generation in order to take advantage of their complementary characters. The aim of this study is to explore renewable sources combined with non-renewable source to generate electricity with the objective of establishing an optimal design for a hybrid solar-wind-diesel energy plant that minimizes cost. The capacity factor of the standalone system was determined for the study area. The cost of energy for the hybrid optimal mix was determined. Levelised cost of energy was also used to determine the cost of energy for standalone power system. The result shows that the energy generated 200 MW hybrid system is 392 GWh with a cost of energy of $0.24/kWh (47.8/kWh). The energy produced can power 39,200 homes in a year. The optimisation shows that the number of solar system, wind and diesel are 699, 1 and 300 respectively. The cost of energy for the standalone system was $0.06/kWh, $0.08/kWh and $0.27/kWh for wind, solar and diesel system. The capacity factor was 56%, 21% and 80% for wind, solar and diesel system. There is a reduction in the amount of greenhouse gases released to the environment alongside with cost of energy generation. Hybrid power generation system is good and effective solution for power generation than conventional energy resources.

A Versatile Industrial Timer and Real Time Keeper

Industrial timer requirements are multifaceted. On-delay, off-delay, cyclic or sequential timing requirements, with usual time range varying from seconds to days, depending on the process. Custom build timers cannot provide all of these requirements simultaneously and hence an advanced timer rectifying this shortcoming has been designed and fabricated in this work. This timer is based on the real time clock chip used in mother boards. Our design can be programmed for a specific time requirement and can later be put to work in standalone mode. A demonstration board is fabricated and tested.