新导则下天然气长输管道项目的环境风险评价

城市地理空间大数据在大数据时代扮演着重要角色,当今大多数数据本质上是空间数据,通过无处不在的位置感知传感器进行采集、管理、存储和分析地理空间数据流,可为商业、科学和工程的发展提供新的决策支持.然而大数据的处理极具挑战性,对于地理空间大数据更是如此,因为大量的数据集必须同时考虑空间和时间的前提下进行分析,高性能计算以其基本的分而治之思想为地理空间大数据的处理提供了必要的解决方案.本文探讨了高性能计算处理地理空间大数据的关键技术,包括地理空间大数据存储与管理、空间索引技术以及并行任务调度技术,对高性能计算用于城市地理空间大数据处理的未来研究方向进行了展望,雾计算、地理人工智能和异构环境下全球统一参考框架将成为高性能计算处理地理空间大数据的重要研究方向.     

Propagation properties of foreshock cavitons: Cluster observations

Foreshock cavitons are transient phenomena observed in the terrestrial foreshock region. They are characterized by a simultaneous depression of magnetic field magnitude and plasma density, which are bounded with enhancements of these two parameters and surrounded by ultralow frequency(ULF) waves. Previous studies focused on the interplanetary magnetic field(IMF) conditions, solar wind(SW) conditions, and the growth of the foreshock waves related to the generation of foreshock cavitons. Previously, a multipoint spacecraft analysis method using Cluster data was applied to analyze only two foreshock cavitons, and this method did not consider uncertainties. In this study, multipoint spacecraft analysis methods, including the timing method, the minimum directional derivative(MDD) method, and the spatiotemporal difference(STD) method are applied to determine the velocity in both spacecraft and solar wind frames. The propagation properties show good agreement with previous results from simulations and observations that most cavitons move sunward in the solar wind frame, with the velocities larger than the Alfvén speed. The propagation properties of foreshock cavitons support the formation mechanism of cavitons in previous simulations, which suggested that cavitons are formed due to the nonlinear evolution of compressive ULF waves. We find that there is clear decreasing trend between the size of cavitons and their velocity in the solar wind frame. In addition, the timing method considering errors has been applied to study the evolution properties by comparing the velocities with errors of the leading and trailing edges, and we identify three stable cavitons and one contracting caviton, which has not been studied before.Most cavitons should remain stable when they travel toward the Earth's bow shock. The relationship between the size of foreshock cavitons and their distance from the bow shock is also discussed.     

液态深层醋自我薰醅后的风味改良法

近几年来 ,随着社会的进步 ,人民生活水平的提高 ,食醋的需求量日渐增加。为满足广大消费者的需求 ,我厂上马液态深层发酵醋来代替原有固体倒缸醋的生产。随着液态醋的顺利投产 ,大家在体味着出品率的提高带来的喜悦 ,环境的改善带来的舒适 ,以及先进的设备、微机化管理、管道化的物料输送带来的一系列轻松愉快之时 ,也明显感到液态醋自身所存在的颜色淡、后味单薄、口感回味差的不足。对于这种情况 ,目前国内生产厂家主要来用以下途径来解决 :用薰醅或炒米色的方法来增色串香 ;用补加氮源以及醋醪后熟保温的方法来提高色泽 ,改善风味 ;直接…