Morphological Characteristics of Cambodia Mekong Delta and Tonle Sap Lake and Its Response to River-Lake Water Exchange Pattern

Tonle Sap Lake is the largest river-connected lake, buffer area and ecological zone of Mekong River, which plays a huge role in dispelling flood peak and compensating water, and the conservation of biological diversity. The river-lake relationship between Mekong River and Tonle Sap Lake is unique and has always been a major focus in the international community. The land terrain and under-water topography were used to analyze the morphological characteristics of Cambodia Mekong Delta and Tonle Sap Lake. Long series of hydrological data of river-lake controlling stations were used to analyze the water level variation characteristics and water volume exchange pattern between Mekong River and Tonle Sap Lake, and the response relationship to river-lake morphological characteristics were also researched. The results show that: Cambodia Mekong Delta and Tonle Sap Lake Area is low-lying and flat with gentle channel gradient and water surface gradient, making the relationship between water level and area (or volume) smooth. The channel storage capacity of Mekong River and Tonle Sap River is not enough compared to the inflow, so vast flooding plain is extremely prone to be inundated, making the flood relationships between the left and right banks become very complicated. Tonle Sap Lake is a seasonal freshwater lake with water flowing in and flowing out, and the timing and intensity of water exchange with Mekong River are closely related to the water flow resistance at the exit section of Tonle Sap Lake and the cross-sectional area of Tonle Sap River, which can be reflected by the river-lake water level difference and the water level of Tonle Sap River. Affected by the river-lake morphological characteristics, the water exchange intensity between Mekong River and Tonle Sap Lake is great. Tonle Sap Lake not only stores 14.4% of flood volume (39.7 billion m3) from the Mekong River every year, but also supplies 29.7% of dry water (69.4 billion m3) to the Mekong River. Influenced by the adjustment of the floodplain, the water level fluctuation of Mekong River and Tonle Sap Lake is slow, and the rising and droop rates of water level are positively correlated with the floodplain storage area. The research results will help to understand the relationship mechanism between Mekong River and Tonle Sap Lake and provide a scientific basis for the comprehensive governance of Cambodia Mekong Delta and Tonle Sap Lake Area.

Patterned catalyst layer boosts the performance of proton exchange membrane fuel cells by optimizing water management

Mass transport is crucial to the performance of proton exchange membrane fuel cells,especially at high current densities.Generally,the oxygen and the generated water share same transmission medium but move towards opposite direction,which leads to serious mass transfer problems.Herein,a series of patterned catalyst layer were prepared with a simple one-step impressing method using nylon sieves as templates.With grooves 100μm in width and 8μm in depth on the surface of cathode catalyst layer,the maximum power density of fuel cell increases by 10%without any additional durability loss while maintaining a similar electrochemical surface area.The concentration contours calculated by finite element analysis reveal that the grooves built on the surface of catalyst layer serve to accumulate the water nearby while oxygen tends to transfer through relatively convex region,which results from capillary pressure difference caused by the pore structure difference between the two regions.The separation of oxidant gas and generated water avoids mass confliction thus boosts mass transport efficiency.

Micromagnetic simulation with three models of FeCo/L1_0 FePt exchange-coupled particles for bit-patterned media

Compositing soft and hard materials is a promising method to decrease the coercivity of L10 FePt, which is considered to be a suitable material for bit-patterned media. This paper reports the simulation of three models of FeCo/L10 FePt exchange-coupled composite particles for bit patterned media by the OOMMF micromagnetic simulation software： the enclosed model, the side-enclosed model, and the top-covered model. All of them have the same volumes of the soft and hard parts but different shapes. Simulation results show that the switching fields for the three models can be reduced to about 10 kOe （1 Oe = 79.5775 A/m） and the factor gain can be improved to 1.4 when the interface exchange coefficient has a proper value. Compared to the other models, the enclosed model has a wider range of interface exchange coefficient values, in which a low switching field and high gain can be obtained. The dependence of the switching fields on the angle of the applied field shows that none of the three models are easily affected by the stray field of a magnetic head.

The influence of patterned microporous layer on the proton exchange membrane fuel cell performances

The ordered membrane electrode assembly(MEA)has gained much attention because of its potential in improving mass transfer.Here,a comprehensive study was conducted on the influence of the patterned microporous layer(MPL)on the proton exchange membrane fuel cell performances.When patterned MPL is employed,grooves are generated between the catalyst layer and the gas diffusion layer.It is found that the grooves do not increase the contact resistance,and it is beneficial for water retention.When the MEA works under low humidity scenarios,the MEA with patterned MPL illustrated higher performance,due to the reduced inner resistance caused by improved water retention,leading to increased ionic conductivity.However,when the humidity is higher than 80%or working under high current density,the generated water accumulated in the grooves and hindered the oxygen mass transport,leading to a reduced MEA performance.

AStudy ofthe Balanced Area of Index's Fluctuation in Shanghai Stock Exchange

Chinese stock market is a developing one. In the present stages, to control scientifically the expansion speed and avoid drastic fluctuations is an important problem. Through analysis of plenty of data of SSE(Shanghai Stock Exchange) Index and relevant economic quotas, we find that the problem of predicting SSE Index is a typical multi variable, nonlinear one. On the basis of the analysis, we apply the technology of fuzzy pattern recognition, to the optimum pattern division of SSE Index's time alignments from Jan. of 1993 to Dec. of 1997, and get a balanced pattern of the stock index fluctuation. At the same time, by using database technology, we find the optimum expansion speed of Shanghai stock, which can make SSE Index fluctuate steadily within the balanced area. We verified this model with the latest data and found it coincides with the reality perfectly. So it has the practical value and provides the policy makers with a scientific basis in controlling the expansion pace.

民族地区职业教育国际交流与合作的实践样态与优化路径

在新时代背景下,民族地区职业教育积极深化国际交流与合作,通过广泛招收国际学生、促进师生互访交流、开展合作办学项目、推进对外援助计划、设立应用外语专业、搭建国际交流平台六大办学实践举措,大大提升了民族地区职业教育对外开放水平。这些国际交流与合作实践展现出了三大显著特点:鲜明的民族地缘区域特色、多元化的合作层次与形式和显著的民族特色文化交流合作。文章结合民族地区职业教育发展实际,从树立国际化思维理念、构建国际化师资队伍、创新国际化专业内涵及推动产教融合国际化四个方面,提出了民族地区职业教育国际化发展的有效路径,为民族地区职业教育发展提供有益参考。

以旅游“三交”铸牢中华民族共同体意识的理路

旅游高质量发展具有促进各民族交往交流交融的历史价值和时代意义,对铸牢中华民族共同体意识发挥重要驱动和链接作用。作为兼具文化互动和个体能动的现代服务业,旅游从“物质性—社会性—个体性”多方面嵌入各民族“三交”的具体交往实践和真实生活空间。在流动的现代社会,旅游活动能够建立跨文化动态关联,塑造多民族良序社会愿景和多维度认同,为推进中华民族共同体建设提供独特价值。为讲好旅游“三交”的中国故事,向世界展示中华文明的独特魅力,须以民族地区的旅游发展为内驱力,统筹中华民族的统一性与多样性,构建民族团结与主客互信的目的地,强化文化自觉自信与家国认同。

Numerical and experimental study on the falling film flow characteristics with the effect of co-current gas flow in hydrogen liquefaction process

Liquid hydrogen storage and transportation is an effective method for large-scale transportation and utilization of hydrogen energy. Revealing the flow mechanism of cryogenic working fluid is the key to optimize heat exchanger structure and hydrogen liquefaction process(LH2). The methods of cryogenic visualization experiment, theoretical analysis and numerical simulation are conducted to study the falling film flow characteristics with the effect of co-current gas flow in LH2spiral wound heat exchanger.The results show that the flow rate of mixed refrigerant has a great influence on liquid film spreading process, falling film flow pattern and heat transfer performance. The liquid film of LH2mixed refrigerant with column flow pattern can not uniformly and completely cover the tube wall surface. As liquid flow rate increases, the falling film flow pattern evolves into sheet-column flow and sheet flow, and liquid film completely covers the surface of tube wall. With the increase of shear effect of gas-phase mixed refrigerant in the same direction, the liquid film gradually becomes unstable, and the flow pattern eventually evolves into a mist flow.

竖直多波纹板式换热器内R134a的流动沸腾实验研究

针对竖直多波纹板片内R134a的流动沸腾进行实验研究,采用高速相机捕捉并分析两相流型的衍变规律,分析干度对换热系数、压降的影响。结果表明:板片内部的汽液相于其所处平面沿水平方向存在交替分布特征;随着干度上升,板片左上角部分流域出现相对停滞的液膜区,其面积随着干度的增加而扩大;波纹板片内的主导换热机制由核态沸腾逐渐转变为对流沸腾。当干度x较低时(x<0.4),换热系数随干度的增加缓慢增加;随后换热系数随干度的上升速率加快(0.4<x<0.6),并于x=0.6时达到最大值;高干度时(x>0.7),板片内出现局部干涸现象,换热系数迅速下降。当质量通量相同时,板片的摩擦压降随干度的增加而增加,而饱和压力的上升会使得摩擦压降有所降低,最大降幅为20.4%。

明代杂宝纹及其在日本与朝鲜半岛的传播与发展——以明代丝绸经面为研究中心

杂宝纹是中国传统装饰纹样之一,在明代已发展为相对成熟的纹样,其造型小巧、寓意吉祥。杂宝纹被巧妙地织入各种题材纹样的丝绸之中,并随当时的海外贸易,经由海上丝绸之路传入日本及朝鲜半岛,为异国的丝绸拥趸所关注。文章以明代传世丝绸经面为基础,通过类比日本、朝鲜半岛相似纹样的织物,探究明代丝织品上杂宝纹的题材、造型、构图、组合等特征,以及其所反映出的中日朝纺织艺术的传播与交流。

17—19世纪华瓷西传后的设计延续与嬗变——以“垂柳纹”为例

17—18世纪,中国情趣风靡西欧,尤以瓷器为盛,催生了西欧长达一个多世纪的崇华热潮。进入19世纪,“中国热”式微,但中国风设计在瓷器上仍存续,这些设计元素在瓷器纹饰中表现的尤为直观。以19世纪风靡西欧的“垂柳纹”为研究对象,在华瓷西传及华风西渐和西风东渐并存的时代背景下,通过图像形成的动因、中国元素的演化和图像的叙事生成几个方面来探究“垂柳纹”中所映射出的文化互融性,为当下中西文化交流与互鉴提供设计参考。

热致变色纱线在小花纹织物设计中的应用

热致变色纱线是智能材料之一,其在医疗、柔性显示、艺术等领域有一定的应用。为了更好拓展其在服用织物上的应用,利用热致变色纱线,结合小提花组织、重纬组织和表里换层组织,设计与开发了三种不同类型的小花纹织物。利用小提花组织,结合全幅热致变色纱线,设计与开发了满地抽象小花纹织物,织物变色前后呈现出不同的如彩虹状的色相;利用重纬组织和平纹组织结合热致变色纱线和普通纱线,设计与开发了清地具象“牛”图案的小花纹织物,织物色彩丰富、图案有趣;利用表里换层组织结合热致变色纱线和普通纱线设计与开发出几何小花纹织物,在白色地的基础上呈现出不同色块的变化。这三块织物具有色彩丰富、变化有趣的特点,可广泛应用于童装、定制服装、箱包等日常生活用品中,为热致变色产品的开发与设计提供了一种新思路。

质子交换膜表面图案化技术进展

介绍了燃料电池的种类和特点,尤其是质子交换膜燃料电池(PEMFC)的技术优势、应用领域和商业化面临的主要技术障碍。简述了膜电极组件(MEA)的结构及质子交换膜(PEM)在其中的作用,指出PEM表面图案化是提升燃料电池在高温低湿条件下综合性能的一个重要方法。总结了近年来PEM表面图案化的基本策略,包括模板铸膜法、模板压印法、辐照修饰法、表面打印和微观相分离法等,并探讨了各自的优缺点。讨论了图案化存在的问题和面临的挑战,并对未来发展方向进行了展望。

唐代织锦联珠纹样在国潮服装中的设计应用

研究唐代织锦连珠纹样的艺术和丝绸工艺成果,在国潮设计中将中国文化元素和时尚潮流结合应用于中国时装文化的魅力表现,显示出包容万象的大国风貌。

EVOLUTION OF LIQUID WATER CONTENT IN A SEA FOG CONTROLLED BY A HIGH-PRESSURE PATTERN

On March 16–17, 2008, a sea fog occurred in Dianbai in the west of Guangdong Province and was accompanied by a high-pressure synoptic system. Using comprehensive observation datasets, this study analyzes the evolution of liquid water content during this sea fog and investigates the relationships between liquid water content and the average diameters and count densities of fog droplets, air temperature, wind speed and turbulence exchanges. The main results are presented as follows. (1) The sea fog showed a quasi-periodic oscillation characteristic, i.e., it developed, disappeared and then developed again. (2) During the sea fog, the number of fog droplets changed significantly while the changes in average diameter of the fog droplets were relatively small. The development and disappearance of the sea fog correlated significantly with the fog droplet numbers. (3) The air-cooling mechanism played a significant role in sea fog formation and development. However, the influences of this mechanism were not evident during fog persistence. (4) During sea fog formation, weak turbulence exchanges were helpful for fog formation. During sea fog development and persistence, liquid water content increased when turbulence exchanges weakened, and vice versa. The changes in turbulence exchanges were closely related to the quasi-periodic oscillations observed in sea fog presence.

Pattern Formation Control Using QR-Code for Mobile Robots

The article presents multi-pattern formation exchange of mobile robots according to the image signals, programs motion paths using A＊ searching algorithm, and avoids the collision points of motion paths. The system contains an image system, a grid based motion platform, some wireless Radio Frequency （RF） modules and five mobile robots. We use image recognition algorithm to classify variety pattern formation according to variety Quick Response （QR） code symbols on the user interface of the supervised computer. The supervised computer controls five mobile robots to execute formation exchange and presents the movement scenario on the grid based motion platform. We have been developed some pattern formations according to game applications, such as long snake pattern formation, phalanx pattern formation, crane wing pattern formation, sword pattern formation, cone pattern formation, sward pattern tbrmation, T pattern formation, rectangle pattern formation and so on. We develop the user interface of the multi-robot system to program motion paths for variety pattern formation exchange according to the minimum displacement. In the experimental results, the supervised computer recognizes the various QR-code symbols using image system and decides which pattern formation to be selected on real-time. Mobile robots can receive the pattern formation command from the supervised computer, present the movement scenario from the original pattern formation to the assigned pattern formation on the motion platform, and avoid other mobile robots on real-time.

中国大型LNG/FLNG绕管换热器研发进展与工业化应用

大型LNG/FLNG绕管换热器是FLNG和大型LNG生产建设的核心装备,技术门槛高,长期由美国APCI和德国Linde公司垄断。本文全面回顾了中国在大型LNG/FLNG绕管换热器研发和工业化应用方面的最新进展,主要包括:①构建了适用于烷烃工质冷凝与沸腾流动的高精度数值模拟方法,提升了数值计算的准确性和稳定性,数值模拟结果与实验数据相对误差在±20%以内;揭示了晃动及结构参数对烷烃工质复杂相变流动传热的影响机制,建立了烷烃工质复杂相变流型转换准则与分流型的流动换热关联式;开发了具有自主知识产权的大型LNG/FLNG绕管换热器仿真设计软件,其仿真结果与现场运行数据平均相对误差小于5%。②研制了300 m以上超长无缝换热铝合金管及3种适用于LNG/FLNG绕管换热器的新型均布器,形成了基于铝换热管的大型LNG/FLNG绕管换热器结构优化设计技术,开发出了中国首套全铝制30万m3/d LNG/FLNG绕管换热器,通过了CCS认证,并制定了相关企业标准。③搭建了全球首个LNG/FLNG绕管换热器工业化测试平台,完成了首套全铝制30万m3/d LNG/FLNG绕管换热器静止和晃荡工业化应用测试,结果表明国产LNG/FLNG绕管换热器在换热等方面性能良好。相关研究成果为未来自主设计和建造大型LNG/FLNG绕管换热器奠定了基础。

多元文化交融视角下中国古代织物莲纹造型研究

莲纹作为中国传统纹饰突出的代表之一,在古代染织纹样史研究中,较少从多角度解读其映照的跨文化交流。文章结合现存实物考证,梳理莲纹造型流变,分析其所见丝绸之路多元文化交融及对外国纺织品的影响。研究认为:早期莲纹基于“十”字形结构发展为“四叶式”,具有本土自身的发展体系。北朝至唐代织物中“莲座”图式受到古希腊罗马建筑和犍陀罗艺术的影响,“莲花化生”图式映射出佛教生命思想及世俗吉祥寓意;由“宝相莲花”图式管窥中日纺织艺术交流,“滴珠窠”图式是蒙元时期中国与伊朗纺织文化交流的例证,文艺复兴时期欧洲纺织品中石榴形莲纹反映了中国莲花原型的跨文化传播。

横掠管束降膜流动和传热特性

为了明确绕管式换热器壳侧降膜流动特性对传热性能的影响,建立三维壳侧计算域,采用VOF模型,在干度工况范围为0.1~0.9,热流密度为1 275~8 000 W/m^(2),质量流率为120 kg/(m^(2)·s)时,分析了乙烷在绕管式换热器壳侧降膜流动过程。结果表明:对于乙烷工质,流型依次为层状流、半环状流、液滴流。干度为0.3,热流密度为4 000 W/m^(2)时为层状流向半环状流转化点;干度为0.6和0.7,热流密度4 000 W/m^(2)时为半环状流向液滴流转化点;在层状流向半环状流及半环状流向液滴流转化点传热系数均下降。干度为0.1~0.2,传热系数与干度成正相关;干度为0.3~0.7,传热系数与干度成负相关;干度为0.8~0.9,传热系数随干度变化不明显;流型为层状流和半环状流时,热流密度与传热系数成正相关。流型为液滴流时,热流密度与传热系数成负相关。

SIMULATION AND ANALYSIS OF FLOW PATTERN IN CROSS-CORRUGATED PLATE HEAT EXCHANGERS

Using numerical methodology, the flow fields between two corrugated plates with different values of the corrugation inclination angle β were simulated. The simulation results directly indicate that β affects the flow pattern between corrugated plates, and the results are in good agreement with the experimental results reported by interrelated literature. The results show that the flow pattern between the two plates changes from ＂double cross-flow＂ to ＂zigzag flow＂ with the increase in β. The reason for the effect on the flow pattern between the two corrugated plates was discussed from the view of the variation of momentum in the direction of corrugation with the variation in β.