A group Undo/Redo method in 3D collaborative modeling systems with performance evaluation

Undo/Redo is an indispensable function in 3D collaborative modeling systems where a single mistake conducted by one user is propagated to all participants. Both intention preservation and consistency maintenance should be satisfied when applying group Undo/Redo. Besides, fast local responsiveness and timely group awareness are accepted performance metrics in interactive systems. In this paper, we contribute a novel group Undo/Redo mechanism for 3D collaborative modeling systems to support the “any time, any where” Undo/Redo. Response time will be shortened noticeably with a Model State Stream kept on each collaborative site. In the case of concurrent Undo/Redo, an Undo State Vector is proposed to ensure the Undo/Redo intention preservation and model consistency maintenance. Furthermore, the paper studies the performance of the algorithm including the worst, best and average cases with theoretical analyses. Our experiments show that responsive time is actually depending on a number of factors such as size of the history buffer, execution time for a single modeling operation.     

Facile fabrication of spherical architecture of Ni/Al layered double hydroxide based on in situ transformation mechanism

Spherical architectures of nickel–aluminum layered double hydroxide (NiAl‐LDH) with hydrotalcite‐like nanoflakes as building blocks were facilely fabricated by precipitation reaction in aqueous solution without any surfactants and organic solvents. Growth of such unique structure undergoes preorganization of primary nanospheres of colloidal amorphous aluminum hydroxide (AAH) in solution, followed by nucleation and crystallizaion of LDH from exterior to interior of AAH spheres by an in situ transformation mechanism. The structure and morphology of LDH spheres depend on both starting raw materials and synthetic parameters including reaction time, reaction temperature, and aqueous ammonia dosage. NiAl‐LDH sphere as positive electrode material delivers improved rechargeable and discharge capacity, with the highest discharge capacity of 173 mAh g^?1 at a current density of 30 mA g^?1 within a potential range from ?0.1 to 0.45 V in 10 mol L^?1 KOH solution, due to the faster diffusion processes in the spherical architecture than the powder sample. © 2014 American Institute of Chemical Engineers AIChE J 60: 4027–4036, 2014     

Engineered morphologies of layered double hydroxide nanoarchitectured shell microspheres and their calcined products

CoFe^IIFe^III-layered double hydroxide (LDH) hollow spheres with two distinctly different hierarchical morphologies—flower-like and raspberry-like, involving edge-on and face-on oriented LDH platelets as building blocks, respectively—can be fabricated by tuning the rate of addition of NaOH solution in a coprecipitation process with sulfonated polystyrene spheres as a template. Ex situ pH-dependent microscopic observations of the formation of the flower-like LDH shells shows the details of non-classic nucleation and growth underlying the edge-on orientation. After calcination, the resulting CoFe₂O₄ materials retain the hierarchical morphology of the corresponding LDH precursor. The hollow CoFe₂O₄ spheres with raspberry-like morphology exhibit magnetic properties comparable to a reference material obtained by calcination of a conventional LDH powder precursor. Similar materials with tunable magnetic properties can be prepared by virtue of the flexibility in LDH layer composition. The CoFe^IIFe^III-LDH spheres with a raspberry-like morphology may be also be prepared by using a scalable procedure involving separate ultra-rapid nucleation and aging steps in a modified colloid mill reactor. The results reported here may open up the possibility of producing shell structures with controllable morphologies and properties on a large scale.     

水解—接触氧化工艺处理屠宰废水研究

针对屠宰废水对普通活性污泥法冲击负荷大的问题,采用水解-接触氧化工艺处理屠宰废水。研究表明,该工艺对COD和氨氮的去除效果好,处理出水水质达到《污水综合排放标准》(GB8978-1996)的二级标准。     

Preparation and wetting properties of layered double hydroxide colloidal nano/microspheres with tunable flower-like morphologies

Layered double hydroxides (LDHs), known as a type of multifunctional anionic layered clay, typically exhibit stability and intrinsic hydrophilicity at neutral and alkaline pH. We herein report a polymer bead-templated preparation of flower-like LDH shell microspheres with the LDH platelets tuned under different aging durations and temperatures. Thickness of LDH shell walls was tuned readily by varying preparation conditions such as aging durations and temperatures. After a simple chemical surface modification using fluorine-silane molecule, the flower-like LDH nano/microspheres show the distinctly different transitions from the intrinsic hydropholicity to the superhydrophobicity at pH 2 and neutral pH. In contrast, at alkaline condition of pH 12 small flower-like spheres were formed atop of the parent microspheres, which may be argued in terms of a process of desorption of silane molecule at the alkaline condition combined with dissolution and reassembly of LDH platelets. Our finding of the superhydrophobic LDH spheres may find useful applications in chemical and biosensors against harsh acidic conditions.     

高掺量矿物掺合料在超大基础底板混凝土中的研究和应用

针对大体积混凝土的施工要求,对高掺量矿物掺合料混凝土进行一系列技术论证试验,并成功应用于北京电视中心工程超大尺寸基础底板混凝土的浇筑施工.     

模糊控制技术在高楼恒压供水系统中的应用

本文介绍了一种基于模糊控制原理的变频调速恒压供水系统,包括模糊控制策略的设计思想,并结合单片机和变频调速技术对系统进行了实现,解决高楼供水系统内压力负荷不稳定及节能等问题,提高了供水系统的自动化程度。     

An GPU accelerated finite difference method for heat transfer simulation

The heat transfer mathematic models are widely used in iron and steel industry area.Many computational models that represent this physical process is based on finite difference methods.The simulation of these phenomena demands a high computational cost.In this paper we employ GPU for the development of algorithm for a two-dimensional heat transfer problem with finite difference methods.The performance evaluation has been made and the comparison between CPU and GPU were discussed.The experimental result shows that GPU can solve this problem more efficiently when we need to divide calculation material into a large number of meshes.     

分布式协同设计技术综述

分析了分布式协同设计中的关键技术问题，介绍了其目前的主要研究进展和代表性成果．在集成技术方面，重点阐述了CAX／DFX工具的分布集成问题，包括封装、互操作、本体论；在协同技术方面，集中分析了异步协同设计、同步协同设计和协同装配设计；最后对该领域需要解决的深层次问题进行了讨论。     

Single image haze removal for aqueous vapour regions based on optimal correction of dark channel

Haze removal is an interesting topic in multimedia and image processing for many applications. Specially for the automatic piloting of ships, the haze removal technology for aqueous vapour regions plays a key role in safe piloting. However, the existing haze removal methods did not dehaze well for these areas. Based on this motive, this paper presents a new haze removal approach to improve the dehazing effect for aqueous vapour regions, in which we design two new computing mechanisms. The first one is to propose a new gradient change model of the dark channel value related to aqueous vapour regions. The second one is to design an optimized and iterated correction method for the dark channel of aqueous vapour regions. Finally, based on these two computing mechanisms, a dynamic iterative optimal correction model is presented to solve the proposed method. Both the visual and the quantitative experiments demonstrate the proposed method outperforms both the family methods of dark channel prior and the deep learning-based methods in aqueous vapour regions. In conclusion, the proposed method can effectively remove the haze in aqueous vapour regions.