高性能MCU的FPGA原型验证系统研究与平台实现

本文研究并实现了一种基于Cortex-A7核的高性能MCU在FPGA原型阶段的验证平台。该设计研究可以针对高性能MCU芯片或其FPGA原型验证阶段的软硬件验证环境快速搭建,通过交互式、软硬件协同的方式对MCU芯片各个模块功能进行实时、可靠的功能验证。高效的FPGA原型验证可以提高MCU研发速度、缩短验证时间、提高验证效率、及时发现芯片设计的缺陷、缩短芯片研发周期。     

基于前向纠错的自适应网络传输机制

针对无线网络中的传输控制协议（TCP）因为丢包触发丢包重传机制而导致传输性能大幅下降的问题,提出了一种基于前向纠错的自适应传输机制（AdaptiveFEC）。该机制通过前向纠错来减少数据段的丢失,以避免触发TCP的丢包重传机制,从而达到提升TCP传输性能的目的。首先,根据当前的网络状况以及当前连接的数据传输特征确定当前时间段中的最优冗余段比例;然后,利用TCP数据段中的数据段序号信息实时进行网络状况的估计,从而根据网络波动来动态更新冗余段比例。大量实验结果说明,在20 ms的往返时延以及5%丢包率的传输环境中,相较于静态的前向纠错机制,AdaptiveFEC能够使得TCP连接的传输速率平均提升42%,当运用在文件下载的应用中时,所提机制能够使得下载速度提升至原来的两倍。     

低渗透储层类型划分及储层敏感性主控因素——以渤海海域古近系为例

利用岩石薄片鉴定、扫描电镜分析、储层敏感性实验等多种分析手段,对渤海海域低孔低渗储层的类型进行了详细划分,并对各类储层发育段的储层敏感性特征及其对应的黏土矿物特征、含量和分布规律进行了详细研究,分析了不同沉积条件对储层敏感性的影响。研究结果表明,渤海海域低渗透储层可划分为富高岭石型、富伊利石型、富绿泥石型、碳酸盐致密胶结型。通过将低渗透储层成因与储层敏感性建立关联,提出了储层敏感性主要受控于母岩类型、古气候条件、沉积微相3个因素：①母岩类型对研究区古近系碎屑岩储层演化起决定性影响。研究区主要具有3种类型的母岩：以中基性火山岩为母岩的碎屑岩储层、以中酸性火山岩为母岩的碎屑岩储层为火山碎屑—高岭石型、以变质岩为母岩的碎屑岩储层为伊利石型。②古气候条件对储层敏感性起到了重要影响。③沉积微相直接影响黏土矿物分异,沉积微相还间接影响后期成岩作用。     

对称转台在微波器件加工过程中的应用

为提高微波器件的加工合格率,将对称转台应用于微波器件加工的硬件设施中,并分析了对称加工的特点。以某微波器件加工为例,简要介绍了对称转台的应用。实践证明,对称转台的使用提高了微波器件的加工质量、降低了成本。     

Research on Failure Occurred During Switching in Bypass Pair of Valve Base Electronics for Converter Station

In the paper"Research on Failure Occurred During Switching in Bypass Pair of Valve Base Electronics for Yulong Converter Station,"the author proposed a control strategy basedon shortest job first algorithm.Shortest job first     

The Comparison of Reflectance based on Different Terrain Correction

Selecting the Xinglong Mountain which locates in the southeast of Lanzhou city，GanSu province as an example.Using the Landsat8 satellite image as the data source，the Cosine method，C and the modified Minnaert methods were used for each band in the study area.Comparing with the results of the field measurement reflectance and the statistical characteristics of image，the result showed that the cosine method has a perfect correction in the visible and short wave infrared wavelength，the C correction has a serious over\|correct，however.In the Near Infrared Wavelength，the better result obtained by C correction，and the cosine method has over\|correct otherwise.Comparing with the correct effect of whole bands，the modified Minnaert method has an ideal correct effect.The comparison of before and after correction we found that there is a smaller difference for three methods in the smaller slope，and the over correct is mostly in the south.What’s more，with the increase of the slope，the over correct is more obviously，but，there is a little over correct which used the modified Minnaert method in the whole area，it’s more suitable in large slope and the complicated area.     

Investigation and analysis of arc ablation on WCu electrical contact materials

In this paper, arc ablation behavior of tungsten–copper (WCu) alloy contacts was investigated by the measurement of weight-loss, or erosion rate, and microstructures of tungsten–copper alloy contacts were examined by using scanning electron microscopy after electrical breakdown process. Experimental results showed that the arc erosion process started at the tiny sharp edges, then the arc spreaded on the second phases, or copper phase on the surface. Because of electrons/ions bombardment, the rapid evaporation and sputtering of liquid copper droplets were serious. As a result, an even contact surface became rugged, and tungsten skeleton remained because of being less eroded. With the increase of applied breakdown voltage, the ablation of tungsten–copper alloy became more significant. The WCu alloys with a higher content of copper showed more severe erosion rate as compared with that with a higher tungsten content under the same erosion conditions. Furthermore, when the number of breakdown is less, WCu alloys with a high copper content are easier for erosion for the conditions of fewer numbers of breakdowns. Whereas, WCu alloys with a high content of tungsten are easier for ablation for the conditions with many times of arc breakdown.     

Re‐exploration of the Codon Context Effect on Amber Codon‐Guided Incorporation of Noncanonical Amino Acids in Escherichia coli by the Blue–White Screening Assay

The effect of codon context on amber codon‐guided incorporation of noncanonical amino acids (NAAs) has been previously examined by antibiotic selection. Here, we re‐explored this effect by screening a library in which three nucleotides upstream and downstream of the amber codon were randomised, and inserted within the lacZ‐α gene. Thousands of clones were obtained and distinguished by the depth of blue colour upon exposure to X‐gal. Large‐scale sequencing revealed remarkable preferences in nucleotides downstream of the amber codon, and moderate preferences for upstream nucleotides. Nucleotide preference was quantified by a dual‐luciferase assay, which verified that the optimum context for NAA incorporation, AATTAGACT, was applicable to different proteins. Our work provides a general guide for engineering amber codons into genes of interest in bacteria.