Exploring the tidal effect of urban business district with large-scale human mobility data

Business districts are urban areas that have various functions for gathering people, such as work, consumption, leisure and entertainment. Due to the dynamic nature of business activities, there exists significant tidal effect on the boundary and functionality of business districts. Indeed, effectively analyzing the tidal patterns of business districts can benefit the economic and social development of a city. However, with the implicit and complex nature of business district evolution, it is non-trivial for existing works to support the fine-grained and timely analysis on the tidal effect of business districts. To this end, we propose a data-driven and multi-dimensional framework for dynamic business district analysis. Specifically, we use the large-scale human trajectory data in urban areas to dynamically detect and forecast the boundary changes of business districts in different time periods. Then, we detect and forecast the functional changes in business districts. Experimental results on real-world trajectory data clearly demonstrate the effectiveness of our framework on detecting and predicting the boundary and functionality change of business districts. Moreover, the analysis on practical business districts shows that our method can discover meaningful patterns and provide interesting insights into the dynamics of business districts. For example, the major functions of business districts will significantly change in different time periods in a day and the rate and magnitude of boundaries varies with the functional distribution of business districts.     

基于VXI总线的导弹自动测试系统研究

本文在深入分析VXI总线以及导弹自动测试特点的基础上,以提高导弹测试的效率和精度为目的,提出了基于VXI总线组建导弹自动测试系统的理想方案,论述了该自动测试系统的功能、硬件构成、软件设计和工作原理.组建成的系统具有操作简便、测试精度高、系统开放等特点,可满足大批量导弹测试的要求.     

质子交换膜中质子输送过程模拟的研究进展

质子的扩散系数、电导率等质子在质子交换膜中的输送参数可以用实验的方法来表征,这些实验技术大多仍停留在用宏观的参数来反映其微观的性能上.运用计算机模拟技术可直接在分子规模描述其输送过程.主要综述了几种质子在质子交换膜中输送过程的模拟方法,讨论了这几种模型在模拟质子输送过程中的一些假设及求解质子输送情况时的大概思路.     

Quantum criticality from Fisher information

Quantum Information Processing - Physical constraints make it challenging to implement and control many-body interactions. For this reason, designing quantum information processes with Hamiltonians...     

当代社会思潮对高校大学生影响的对策研究

多样化的社会思潮给高校思想政治教育带来严峻的挑战,各种社会思潮的相互冲击、碰撞,使部分大学生产生了价值迷惘和信仰危机。社会主义核心价值体系融入高校思想政治教育全过程,坚持以社会主义核心价值体系引领社会思潮,对坚定当代大学生的马克思主义信仰具有重要作用。     

影响医疗垃圾热解特性的主要因素

用TG-DTA差热热重联用分析仪对影响医疗垃圾热解特性的主要因素,包括垃圾种类、升温速率、试样质量、实验终温和保温时间等进行了实验研究。结果表明,垃圾种类不同,表现出的起始温度、终止温度、峰温和失重率等反映医疗垃圾热解特性的主要参数不同;升温速率和试样质量对医疗垃圾热解特性的影响主要表现在起始温度和终止温度方面,而对峰温和失重率的影响较小;实验终温和保温时间的影响则主要表现在医疗垃圾的失重率上,即实验终温越高、保温时间越长,医疗垃圾的失重率越高,而对起始温度和终止温度的影响则可以忽略。     

Synthesis of hydrophobically modified flocculant by aqueous dispersion polymerization and its application in oily wastewater treatment

A hydrophobically modified cationic flocculant, in the form of aqueous dispersion, has been successfully synthesized via dispersion copolymerization of acrylamide (AM), 2‐methylacryloylxyethyl trimethyl ammonium chloride (DMC), and methyl methacrylate (MMA) in aqueous ammonium sulfate (AS) solution. The molecular structure of the prepared copolymer was characterized by nuclear magnetic resonance spectroscopy (NMR). Meanwhile, the influence of hydrophobic comonomer (MMA) on the viscosity and microstructure of this aqueous dispersion was investigated. It was found that both the viscosity and the particle size were decreased with increasing content of MMA. Thereafter, this flocculant was used to treat the oily wastewater, and its oil removal ability was assessed under various conditions. It was demonstrated that the hydrophobically modified flocculant has obvious superiority for oily wastewater treatment. POLYM. ENG. SCI., 55:1–7, 2015. © 2014 Society of Plastics Engineers     

Preparation of bichar/layered double hydroxide@alginate aerogel as a highly efficient adsorbent for Cu2+ and Cd2+

Calcium cross-linked layered double hydroxide-bichar/alginate aerogel (LBCA) was synthesized by ultrasonic-assisted hydrothermal and freeze-drying method. The Mg-Al layered double hydroxide (LDH) was successfully loaded on the bichar (BC) and the LDH-BC was dispersed uniformly in the calcium alginate aerogel, which was confirmed by X-Ray Diffraction, scanning electron microscopy and BET tests. The obtained LBCA was applied to remove the Cu²⁺ and Cd²⁺ in the aqueous solution. As compared with LDH nanosheets, removal rates of LBCA aerogel on Cu²⁺ and Cd²⁺ were ranged from 59% to 94% and 45% to 86%, respectively. The adsorption kinetic data accorded with the pseudo second-order kinetic equation, and the isotherm data were in good agreement with the Langmuir model. Moreover, LBCA aerogel showed good regeneration ability, and raw materials for the fabrication of LBCA aerogel are abundant and low price.     

A versatile strategy towards semi-interpenetrating polymer network for proton exchange membranes

A universal method to prepare proton exchange membrane (PEM) with semi-interpenetrating polymer network (semi-IPN) via a versatile crosslinker 1,3-benzenedisulfonyl azide (1,3-BDSA) is proposed. Sulfonyl azide groups can react with any polymer with carbon-hydrogen bonds via hydrogen abstraction. Polyvinylidene fluoride (PVDF) and perfluorosulfonic acid (PFSA) polymer are selected as two precursors for semi-IPN. When 1,3-BDSA is heated to a sufficiently high temperature it can form the nitrene and connect with PVDF via hydrogen abstraction reaction, recombination, or CH-bond insertion. The crosslinking structure of PVDF is formed, and semi-IPN is constructed in the presence of PFSA at the same time. The mechanical properties, degree of crosslinking, water uptake, and proton conductivity of semi-IPN membranes are investigated. Compared with pure PFSA membrane, the mechanical properties and the dimensional stability of the semi-IPN membranes are improved significantly. The tensile strength of the composite membrane (27.2 MPa) is much higher than that of PFSA membrane (10.1 MPa). The maximum power density of the composite membrane can reach 382 mW cm⁻² at 940 mA cm⁻². Sulfonyl azide based crosslinkers can be used to prepare semi-IPN or IPN PEMs from any paired polymers with carbon–hydrogen bonds.     

Colloid formation in Hanford sediments reacted with simulated tank waste

Solutions of high pH, ionic strength, and aluminum concentration have leaked into the subsurface from underground waste storage tanks atthe Hanford Reservation in Washington State. Here, we test the hypothesis that these waste solutions alter and dissolve the native minerals present in the sediments and that colloidal (diameter < 2 microm) feldspathoids form. We reacted Hanford sediments with simulated solutions representative of Hanford waste tanks. The solutions consisted of 1.4 or 2.8 mol/kg NaOH, 0.125 or 0.25 mol/kg NaAlO4, and 3.7 mol/kg NaNO3 and were contacted with the sediments for a period of 25 or 40 days at 50 degrees C. The colloidal size fraction was separated from the sediments and characterized in terms of mineralogy, morphology, chemical composition, and electrophoretic mobility. Upon reaction with tank waste solutions, native minerals released Si and other elements into the solution phase. This Si precipitated with the Al present in the waste solutions to form secondary minerals, identified as the feldspathoids cancrinite and sodalite. The solution phase was modeled with the chemical equilibrium model GMIN for solution speciation and saturation indices with respect to sodalite and cancrinite. The amount of colloidal material in the sediments increased upon reaction with waste solutions. At the natural pH found in Hanford sediments (pH 8) the newly formed minerals are negatively charged, similar to the unreacted colloidal material present in the sediments. The formation of colloidal material in Hanford sediments upon reaction with tank waste solutions is an important aspect to consider in the characterization of Hanford tank leaks and may affect the fate of hazardous radionuclides present in the tank waste.