地面高精度磁测在新疆青河县贝勒克勒铁矿的应用

通过对新疆青河县贝勒克勒铁矿高精度磁法勘探资料的分析和研究,工作区可划分为西部、北部高磁异常区、中西部负值异常区、中部面积正负磁场平缓变化区、东部跳跃变化正值磁异常区,结合工作区岩矿石标本磁性参数可判别各类磁场类型形成的地质原因。划分局部磁异常6个,其中M1、M2、M3磁异常与地下隐伏含磁铁矿石英岩有关,M4、M5、M6磁异常与含铁石英岩有关。对局部典型异常M1、M4进行了半定量解释,并进行了钻探验证,实际验证结果与推断结果较为吻合。     

音频大地电磁法在秭归盆地页岩气资源调查评价中的应用

在秭归盆地页岩气资源调查评价中,为了了解区内页岩层主要目的层的分布范围和埋藏深度,采用音频大地电磁法进行探测。首先利用音频大地电磁法具有不受高阻层屏蔽、对低阻层分辨灵敏、勘探深度大及适合山区勘探的特点,在野外数据采集过程中,采取了有力的技术措施,确保了数据采集质量;然后在数据处理时利用了先进的反演程序,由经验丰富的地球物理工作者,结合地质资料进行综合解释。探测成果基本查明了评价区内页岩层主要目的层的分布范围和埋藏深度,为页岩气地质参数钻孔的布设提供了有用的基础地质资料。结果表明,在页岩气资源调查评价过程中,利用音频大地电磁法进行探测,可以较好地了解区内页岩层目的层的空间分布情况,其探测效果明显,技术上可行,探测成果可为今后开展页岩气勘探开发提供借鉴依据。     

A neglected GABAergic astrocyte: Calcium dynamics and involvement in seizure activity

Gamma-aminobutyric acid (GABA) contributes substantially to neurocognitive function as an important inhibitory neurotransmitter in the human cerebral cortex. However, the pathophysiology of disorders such as epilepsy are not well understood, since GABA agonists are not quite effective in treating epilepsy. Knowledge of the mechanism of action of GABA would contribute to review previously proposed anti-epileptic processes by GABA agonists. In this study based on recent experiments on GABAergic astrocytes, we developed a modified GABAergic astrocyte model, and successfully simulated a long-lasting Ca²⁺ oscillation in astrocytes after 0.5-s stimulation of GABAergic transmission. We then incorporated this GABAergic astrocyte model into a classical Ullah-Schiff seizure model and surprisingly found that this GABAergic astrocyte model functions to hinder the anti-epileptic action of GABA agonists, thereby explaining their low efficiency in previous experiments. These results also update our knowledge of the mechanism of action of GABA and the effects of astrocytes on physiological and pathological functions of the brain.     

Mechanical analysis of double-layered circular graphene sheets as building material embedded in an elastic medium

Journal of Central South University - Possessing the unique and highly valuable properties, graphene sheets (GSs) have attracted increasing attention including that from the building engineer due...     

浅层地热在皖南古民居中应用前景探讨

本文主要以黟县地区水文和地质资料以及实地调研为依据,提出了井水直接供冷、水源热泵技术、土壤与空气直接换热供冷、农家乐水(地)源热泵系统三联供以及沼气池、太阳能、地源热泵综合应用的五种浅层地热利用在皖南古民居应用的原理以及实现的可能性,对今后皖南地区古民居的可再生能源的利用以及节能提供理论支撑。     

Corrosion mechanism and corrosion model of Mg-Y alloy in NaCl solution

Corrosion of Mg–Y alloy was studied using electrochemical evaluations, immersion tests and SEM observations. Corrosion mechanisms of Mg-(0.25 and 2.5) Y alloy and Mg-(5, 8, and 15) Y alloy were uniform corrosion and pitting corrosion respectively, and the content of Mg_(24)Y_5 phases determined its effect acting as cathode to accelerate the corrosion or corrosion barrier to inhibit the corrosion. Corrosion resistance of Mg-(0.25, 2.5, 5, 8, and 15) Y alloys was as follows: Rt(Mg-0.25Y) Rt(Mg-8Y) Rt(Mg-15Y) Rt(Mg-5Y) Rt(Mg-2.5Y). Y could significantly improve the corrosion resistance of the Mg-Y alloy, but the excess of Y deteriorated the corrosion resistance of the Mg-Y alloy. The optimum content of Y in the studied alloys was 2.5%.     

Improved Computational Model of Grid Cells Based on Column Structure

To simulate the firing pattern of biological grid cells, this paper presents an improved computational model of grid cells based on column structure. In this model, the displacement along different directions is processed by modulus operation, and the obtained remainder is associated with firing rate of grid cell. Compared with the original model, the improved parts include that: the base of modulus operation is changed, and the firing rate in firing field is encoded by Gaussian-like function. Simulation validates that the firing pattern generated by the improved computational model is more consistent with biological characteristic than original model. Besides, the firing pattern is badly influenced by the cumulative positioning error, but the computational model can also generate the regularly hexagonal firing pattern when the real-time positioning results are modified.     

泄洪洞反弧段末端水力特性指标分布规律

龙抬头式泄洪洞在水利水电工程中应用十分普遍,但是由于反弧段流态复杂,其产生空蚀破坏的原因尚不明晰。对不同泄洪洞体型掺气前后的工况进行三维数值计算,对其水力特性指标的分布规律进行研究。结果表明:随着落差Δz增大,反弧段流速逐步增大,水流空化数逐步减小;反弧半径R的改变对反弧段水力参数的影响有限。掺气水流的反弧段水力学指标主要取决于Δz,而受反弧半径R的影响相对较小。当Δz减小时,反弧段末端的水力参数在掺气前后变化不大,反弧段末端下游30m(等于15倍的挑坎高度)处的掺气水流的流速明显降低,空化数明显增高,掺气水流的保护作用对空腔下游部分的水力参数影响更加明显。在反弧末端有二次流出现,两侧边墙附近存在对称涡,不仅对边墙附近的流速压力分布产生一定影响,也加剧了反弧段内的水力特性的复杂程度。     

基于多层注意力机制—柔性AC算法的机器人路径规划

针对行动者—评论家（AC）算法存在的经验学习样本维度高、策略梯度模型鲁棒性低等问题,依据多代理系统的信息协作优势,构建注意力机制网络并作为代理体,引入多层并行注意力机制网络模型对AC算法进行改进,提出一种基于多层并行注意力机制的柔性AC算法。将其用于解决动态未知环境下的机器人路径规划问题,可增强行动者的策略梯度鲁棒性并降低评论家的回归误差,实现机器人路径规划最优方案的快速收敛。实验结果表明,该算法有效克服机器人路径规划的局部最优,具有计算速度快、稳定收敛的优点。     

四维混沌系统及其在图像加密中的应用

传统基于低维混沌系统的图像加密算法往往具有密钥空间较小、安全性较差的问题。针对这些问题,首先提出了一类新的平衡点不稳定的四维离散混沌系统,通过数值仿真对该类系统进行了动力学行为分析,正的Lyapunov指数的个数可以达到三个。同时并基于该类混沌系统设计了一个新的图像加密方案,并进一步对明密文的分布直方图、相关系数、信息熵以及加密方案对参数的敏感性进行了分析。分析结果表明,该加密方案抵抗外来攻击的能力强,密钥空间可达2996△,具有较高的安全性。