Application Layer Multicast Model with Low Delay and High Stability

As an alternative of Internet protocol(IP)multicast,application layer multicast(ALM)is widely used with the advantage of simplicity and flexibility.However,the existing problems of large transmission delay and poor stability limit the application and development.In this article,to solve these problems,an ALM model based on node potential(NP)and topological index(TI)is proposed.The proposed model considers the factors of node capability and node distance in constructing and maintaining multicast tree to reduce transmission delay and increase stability,and thus it improves the application level in real-time multimedia multicast.The computer simulations prove that the proposed model reduces the ALM transmission delay,increases multicast tree stability effectively,and improves the ALM performance,and therefore it is suitable to apply in large-scale real-time multimedia environment.

Effects of Phosphorus Application in Different Soil Layers on Root Growth, Yield, and Water-Use Efficiency of Winter Wheat Grown Under Semi-Arid Conditions

Deep phosphorus application can be a usefull measure to improve crops＇ performance in semi-arid regions, but more knowledge of both its general effects and effects on specific crops is required to optimize treatments. Thus, the aims of this study were to evaluate the effects of phosphorus（P） application at different soil layers on root growth, grain yield, and water-use efficiency（WUE） of winter wheat grown on the semi-arid Loess Plateau of China and to explore the relationship between root distribution and grain yield. The experiment consisted of four P treatments in a randomized complete block design with three replicates and two cultivars： one drought-sensitive（Xiaoyan 22, XY22） and one drought-tolerant（Changhan 58, CH58）. The four P treatments were no P（control, CK）, surface P（SP）, deep P（DP）, and deep-band P application（DBP）. CH58 produced larger and deeper root systems, and had higher grain yields and WUE, under the deep P treatments（DP and DBP） than under SP, clearly showing that deep P placement had beneficial effects on the drought-tolerant cultivar. In contrast, the grain yield and root growth of XY22 did not differ between DP or DBP and SP treatments. Further, root dry weight（RW） and root length（RL） in deep soil layer（30-100 cm） were closely positively correlated with grain yield and WUE of CH58（but not XY22）, highlighting the connections between a well-developed subsoil root system and both high grain yield and WUE for the drought-tolerant cultivar. WUE correlated strongly with grain yield for both cultivars（r=0.94, P〈0.001）. In conclusion, deep application of P fertilizer is a practical and feasible means of increasing grain yield and WUE of rainfed winter wheat in semi-arid regions, by promoting deep root development of drought-tolerant cultivars.

Architecture design and demand analysis on application layer of standard system for ubiquitous power Internet of Things

The ubiquitous power Internet of Things(UPIoT)is an intelligent service system with comprehensive state perception,efficient processing,and flexible application of information.It focuses on each link of the power system and makes full use of the mobile internet,artificial intelligence,and other advanced information and communication technologies in order to realize the inter-human interaction of all things in all links of the power system.This article systematically presents to the national and international organizations and agencies in charge of UPIoT layer standardization the status quo of the research on the Internet of Things(IoT)-related industry standards system.It briefly describes the generic standard classification methods,layered architecture,conceptual model,and system tables in the UPIoT application layer.Based on the principles of inheritance,innovation,and practicability,this study divides the application layer into customer service,power grid operation,integrated energy,and enterprise operation,emerging business and analyzes the standard requirements of these five fields.This study also proposes a standard plan.Finally,it summarizes the research report and provides suggestions for a follow-up work.

Survey on recent advances in IoT application layer protocols and machine learning scope for research directions

The Internet of Things(IoT)has been growing over the past few years due to its flexibility and ease of use in real-time applications.The IoT's foremost task is ensuring that there is proper communication among different types of applications and devices,and that the application layer protocols fulfill this necessity.However,as the number of applications grows,it is necessary to modify or enhance the application layer protocols according to specific IoT applications,allowing specific issues to be addressed,such as dynamic adaption to network conditions and interoperability.Recently,several IoT application layer protocols have been enhanced and modified according to application requirements.However,no existing survey articles focus on these protocols.In this article,we survey traditional and recent advances in IoT application layer protocols,as well as relevant real-time applications and their adapted application layer protocols for improving performance.As changing the nature of protocols for each application is unrealistic,machine learning offers means of making protocols intelligent and is able to adapt dynamically.In this context,we focus on providing open challenges to drive IoT application layer protocols in such a direction.

The Application of Layered Progressive Teaching Method in Nursing Teaching of Health Management Centre

Objective:To explore the clinical effect of the layered progressive teaching method in the process of nursing teaching in the health management centre.Methods:100 nursing students in the health management centre of our hospital were randomly divided into two groups from April 2018 to April 2019,in which students of the control group were treated with routine teaching,while those of the experimental group were treated with layered progressive teaching.Then,the teaching effect of the two groups was compared and analysed.Results:The assessment results of nursing students in the two groups were compared,in which the theoretical knowledge scores and practical operation scores of nursing students in the experimental group were(94.34±2.33)and(90.45±2.20)respectively.By contrast,the score of students in the control group was lower and the difference between the two groups was not significant(P<0.50).The teaching effect of students in the experimental group is more significant.Conclusion:During the process of nursing teaching in the Health Management Centre,the progressive teaching method showed a significant clinical effect and could effectively enhance students’scores.Therefore,it is positively significant for clinical development.

THE APPLICATION OF DYNAMICSCHLIEREN-PHOTON CORRELATIONTECHNIQUE TO A SUPERSONIC SHEAR LAYER

By applying the dynamic schlieren-photon correlation technique to a two dimensional separated supersonic shear layer, the convection velocity of large eddies inside the shear layer and the frequency of the self-sustaining oscillation of the shear layer induced by the shedding of large eddies have been obtained. The distribution of the turbulence intensity inside the shear layer can also be estimated. It is shown that the method has its promising potentials in the measurement of high speed complex flows.

Pseudohalide induced tunable electronic and excitonic properties in two-dimensional single-layer perovskite for photovoltaics and photoelectronic applications

Two-dimensional(2D) layered organic-inorganic hybrid perovskites have attracted much more attention for some applications than their three-dimensional(3D) perovskite counterparts due to their promising thermal and moisture stabilities.In particular, the 2D perovskite devices have shown better promise for optoelectronic applications.However, tunability of optoelectronic properties is often demanded to improve the device performance.Herein, we adopt a newly method to tune the electronic properties of 2D perovskite by introducing pseudohalide into the structure.In this work, we designed a pseudohalidesubstituted 2D perovskite by substituting the out-of-plane halide with pseudohalide and studied the electronic and excitonic properties of 2D-BA2MX4 and 2D-BA2MX2Ps2(M=Ge^(2+), Sn^(2+), and Pb^(2+);X=I;Ps=NCO, NCS, OCN, SCN, Se CN).We revealed the dependence of electronic properties including band gaps, composition of band edges, bonding characteristics, work functions, effective masses, and exciton binding energies on different pseudohalides substituted in 2D perovskite.Our results indicate that the substitution of pseudohalide in 2D perovskites is energetically favorable and can significantly affect the bonding characteristics as well as the CBM and VBM that often play major role in determining their performance in optoelectronic devices.It is expected that the pseudohalide substitution will be helpful in developing more advanced optoelectronic device based on 2D perovskite by optimizing band alignment and promoting charge extraction.

Application Analysis of Fine-grained Drainage Asphalt Surface Layer in Sponge Urban Road

With the overall progress and development of the market economy,the construction of sponge city has received extensive attention.To further create an environment more suitable for people’s lives,relevant departments should actively apply diversified materials and integrate material supervision mechanisms in the construction of sponge city roads,and construct a systematic road restraint mechanism and management system to ensure that the characteristics of the surface ecological environment can be fundamentally improved.This paper briefly analyzes the pavement structure design mechanism in combination with the engineering project.The application path of the finegrained drainage asphalt surface layer in the sponge city road is explained from the mix ratio of the mixture and the construction process.It is for reference only.

Modeling TCP Incast Issue in Data Center Networks and an Adaptive Application-Layer Solution

In data centers, the transmission control protocol(TCP) incast causes catastrophic goodput degradation to applications with a many-to-one traffic pattern. In this paper, we intend to tame incast at the receiver-side application. Towards this goal, we first develop an analytical model that formulates the incast probability as a function of connection variables and network environment settings. We combine the model with the optimization theory and derive some insights into minimizing the incast probability through tuning connection variables related to applications. Then,enlightened by the analytical results, we propose an adaptive application-layer solution to the TCP incast.The solution equally allocates advertised windows to concurrent connections, and dynamically adapts the number of concurrent connections to the varying conditions. Simulation results show that our solution consistently eludes incast and achieves high goodput in various scenarios including the ones with multiple bottleneck links and background TCP traffic.

Vegetation of mono-layer landfill cover made of coal bottom ash and soil by compost application

Monolayer barriers called evapotranspiration (ET) covers were developed as alternative final cover systems in waste landfills but high-quality soil remains a limiting factor in these cover systems. Coal bottom ash was evaluated to be a very good alternative to soil in previous tests and a combination of soil (65% wt.wt-1) and coal bottom ash (35% wt.wt-1) was evaluated to be the most feasible materials for ET cover systems. In our pot test, selected manure compost as soil amendment for the composite ET cover system, which was made of soil and bottom ash at ca. 40 Mg.ha-1 application level was very effective to promote vegetation growth of three plants;namely, garden cosmos (Cosmosbipinnatus), Chinese bushclover (Lespedezacuneata), and leafy lespedeza (Lespedeza cyrtobotrya). To evaluate the effect of compost application on plant growth in an ET vegetative cover system, two couples of lysimeters, packed with soil and a mixture of soil and bottom ash, were installed in a pilot landfill cover system in 2007. Manure composts were applied at the rates of 0 and ?40 Mg.ha-11before sowing the five plant species, i.e.indigo-bush (Amorphafruticosa), Japanese mugwort (Artemisia princeps, Arundinella hirta, Lespedezacuneata, and Lespedezacyrtobotrya). Unseeded native plant (green foxtail,Setaria viridis) was dominant in all treatments in the 1st year after installation while the growth of the sown plants significantly improved over the years. Total biomass productivity significantly increased with manure compost application, and more significantly increased in the composite ET cover made of soil and bottom ash treatment compared to the single soil ET cover, mainly due to more improved soil nutrient levels promoting vegetation growth and maintaining the vegetation system. The use of bottom ash as a mixing material in ET cover systems has a strong potential as an alternative to fine-grained soils, and manure compost addition can effectively enhance vegetative propagation in ET cover systems.

Preparation,Characterization and Application of ZnAlLa-Hydrotalcite-Like Compounds

The preparation of ZnAlLa-hydrotalcite-like compounds [ZnAlLa-HTLcs] wasstudied. ZnAlLa-HTLcs were synthesized by a method of variable pH with the raw materials ofZn(NO_3)_2, Al(NO_3)_3, La(NO_3)_3, and NaOH. The eS'ccts of some factors (i.e. pH values, the moleratio of Al^(3+) to La^(3+), temperature and the period of hydrothermal treatment) on thepreparation of HTLcs were discussed systematically. XRD, TG-DTA, FT-IR spectroscopy, and ICP wereperformed to characterize ZnAlLa-HTLcs samples, and the thermal stability of HTLcs was alsodiscussed. It was shown that unique ZnAlLa-HTLcs with high crystallinity can be prepared, under theconditions of pH = 5.5-6.5, n(Zn^(2+))/n(Al^(3+) + La^(3+))=2 and the atomic ratio of La^(3+) toAl^(3+) ranging from 0.07 to 2, hydrothermal treatment at 120 ℃ for 5 h. When the calcination ofthe HTLcs is performed at temperatures above 200 ℃, ZnO phase is detected with Al_2O_3 and La_2O_3spreading on its top. The complex metal oxides derived from ZnAlLa-HTLcs at 500 ℃ have highercatalytic activity and selectivity than those from ZnAl-HTLcs for the esterification of acetic acidwith n-butanol under the same reaction conditions.

Principle and engineering application of pressure relief gas drainage in low permeability outburst coal seam

With the increase in mining depth, the danger of coal and gas outbursts increases.In order to drain coal gas effectively and to eliminate the risk of coal and gas outbursts, we used a specific number of penetration boreholes for draining of pressure relief gas.Based on the principle of overlying strata movement, deformation and pressure relief, a good effect of gas drainage was obtained.The practice in the Panyi coal mine has shown that, after mining the C11coal seam as the protective layer, the relative expansion deformation value of the protected layer C13 reached 2.63%, The permeability coefficient increased 2880 times, the gas drainage rate of the C13 coal seam increased to more than 60%, the amount of gas was reduced from 13.0 to 5.2 m3/t and the gas pressure declined from 4.4 to 0.4 MPa, which caused the danger the outbursts in the coal seams to be eliminated.The result was that we achieved a safe and highly efficient mining operation of the C13 coal seam.

Interactive transport of multi-view videos for 3DTV applications

The authors propose a novel method for transporting multi-view videos that aims to keep the bandwidth requirements on both end-users and servers as low as possible. The method is based on application layer multicast, where each end point re- ceives only a selected number of views required for rendering video from its current viewpoint at any given time. The set of selected videos changes in real time as the user’s viewpoint changes because of head or eye movements. Techniques for reducing the black-outs during fast viewpoint changes were investigated. The performance of the approach was studied through network experiments.

Material manufacturing from atomic layer

Atomic scale engineering of materials and interfaces has become increasingly important in material manufacturing.Atomic layer deposition(ALD)is a technology that can offer many unique properties to achieve atomic-scale material manufacturing controllability.Herein,we discuss this ALD technology for its applications,attributes,technology status and challenges.We envision that the ALD technology will continue making significant contributions to various industries and technologies in the coming years.

CARINA:一种高效的解决IoT互操作性的应用层协议转换方案

为了解决物联网设备众多、协议众多,以及协议架构和应用场景不同引发的物联网设备互操作性问题,针对应用层使用广泛的HTTP等4种协议,提出了一种基于协议包解析和关键方法映射的高效可扩展的应用层协议转换方案。考虑到4种协议的基础架构、消息格式、通信模式以及应用场景具有较大差异,该方案通过对协议原始数据包进行解析和关键信息提取,然后统一以键值对的形式进行信息存储,解决了不同协议信息存储的统一性问题。通过构造关键方法映射表,将不同协议的方法进行映射,实现了不同协议之间的互联。实验结果表明,基于所提方案实现的协议转换系统能很好地完成4种协议之间的消息转换。相比同类型的Ponte方法,在相同实验条件下,所提方案的转换速度都优于Ponte,甚至在某些情况下表现出了将近10倍的速度差距,同时支持多出一倍的转换类型。实验结果验证了所提方法在可扩展性和转换时间等效率方面相比同类型的协议转换算法具有显著提升。

不同肥料类型与施肥方式对花生籽仁品质的影响

为进一步探究施肥技术措施(分层施肥技术、减氮增钙技术等)对花生籽仁品质的调控作用,通过设置大田试验,研究施肥技术对花生籽仁品质的影响。试验一:选取2个试验区(济阳、饮马泉),设置0和600 kg·hm^(-2)(Ca_(0)、Ca_(600))2个钙肥水平和0、75、150、225、300 kg·hm^(-2)5个氮肥水平;试验二:设肥料机械分层条施(L)、人工撒施(B)两种施肥方式,选择含有100 d释放期的花生专用缓释复混肥(SF)、普通复合肥(CF),另设不施氮肥对照(N_(0))共5个处理。结果表明:(1)与N_(0)相比,施氮花生籽仁中粗蛋白含量提高1.24~3.57个百分点、总氨基酸含量增加1.19~3.70个百分点、亚油酸含量提升0.93~2.41个百分点,同时部分脂肪酸组分和氨基酸组分含量等均随施氮量的增加有不同程度的提高;但籽仁含油量降低1.70~5.34个百分点。与不施钙处理(Ca_(0))相比,施钙(Ca_(600))处理的籽仁中粗蛋白、总氨基酸含量分别降低0.10~1.55个百分点、0.02~1.23个百分点,但含油量提高0.16~2.62个百分点。氮肥与钙肥配施可减小粗蛋白含量增幅与含油量降幅。“减施氮肥+增施钙肥”栽培技术有利于调控、改善花生籽仁品质。(2)相同施肥方式下,与复合肥(CF)相比,专用复混肥(SF)处理提高了籽仁粗蛋白含量和含油量。与人工撒施(B)相比,分层施用复合肥(CFL)或花生专用复混肥(SFL)花生籽仁粗蛋白、总氨基酸含量分别降低0.34~1.39个百分点、0.14~0.34个百分点,而籽仁含油量增加0.22~1.16个百分点。(3)产量与粗蛋白、总氨基酸、亚油酸含量之间呈极显著正相关(P<0.01),而产量与含油量、油酸含量呈显著负相关。粗蛋白与总氨基酸及组分、亚油酸含量间呈极显著正相关,与含油量存在极显著负相关关系。综上,生产中同时需要多产油和较多粗蛋白时,建议采用减氮增钙绿色高效栽培技术,也可施用花生专用复混肥,配套分层施肥高效栽培技术。

基于1553B总线的大规模信息系统设计问题研究

某大型航天器GNC系统应用1553B总线构建了其规模庞大的信息系统,在信息系统设计过程中产生了3个问题:超长总线下的稳定通信、应用层协议的设计、多条总线的管理等。对这3个问题开展研究,描述了3个问题的由来,给出了问题的解决方法,并验证了方法的实际效果。结果表明:总线中继的方法,有效解决了1553B总线在240 m长度下的稳定可靠通信问题;广播帧计数回传的应用层协议,节省了总线数据通讯开销、并提供了丰富的故障诊断信息;遍历寻优的总线管理策略,最大程度上发挥了多机多总线系统的容错能力。

边界层高度的不同诊断方法在京津冀及周边地区的适用性分析

利用2016~2021年京津冀及周边地区7个站的探空数据,分析了传统的位温梯度法、改进的位温梯度法、相对湿度梯度法、比湿梯度法和理查森数法5种大气边界层高度的诊断方法在京津冀及周边地区大气边界层高度计算的适用性。结果表明:5种方法计算的边界层高度差距在40~1000 m,传统的位温梯度法、相对湿度梯度法、比湿梯度法诊断的边界层高度普遍偏高,且存在较大的结构不确定性,理查森数法和改进的位温梯度法诊断的边界层高度偏低,前者的不确定性最小;5种方法在乐亭、北京、太原3个代表站得到的边界层高度具有明显的季节性和季节内差异,两种湿度法在乐亭呈现夏秋高、春冬低的特点,在北京和太原呈现春夏高、秋冬低的特点,其他3种方法在3个站均是春夏高、秋冬低的特点;相对湿度梯度法和比湿梯度法参数不确定性较大,传统的位温梯度法和改进的位温梯度法次之,理查森数法最小;在边界层高度计算结果月均值的时间一致性上,晚上各方法间的相关性明显高于白天,两种湿度法之间的相关系数始终最高,但与另外3种方法间的相关性均较差,理查森数法和改进的位温梯度法相关性较高,传统的位温梯度法因站点不同,与其他方法间的相关性波动较大。

单脉冲平顶激光清洗CFRP的多物理场特性研究

为探究平顶激光清洗碳纤维增强复合材料(CFRP)的作用机制,本研究考虑CFRP的组分对激光的吸收、反射特性差异显著,将激光载荷分层施加到CFRP的细观有限元模型上,引入热烧蚀-热应力双重作用效果,还原不同能量密度下单脉冲平顶激光清洗形貌,并完成了试验验证。结果表明:分层施加激光载荷较传统表面加载模式能够有效提升仿真精度,采用热烧蚀-热应力双重判据能够进一步提升形貌还原效果,本研究模型的仿真形貌长轴贴合度不低于96.64%,面积贴合度达到80.00%,并通过高精度模型瞬时温度场分布能够指导激光清洗CFRP表面树脂的实际工艺。

船舶气层减阻技术研究综述

随着全球生态环境变化的要求以及我国“碳达峰、碳中和”目标的提出,船舶气层减阻技术作为船舶运输手段中一种有效的节能、降碳手段,近年来备受关注。文章阐述了气层减阻技术中气层的形成过程以及工作原理;从模型试验以及理论与数值计算方面分析了船舶气层减阻技术的发展和研究现状;列举分析了国内外部分研究单位的应用实例和实际效果;针对研究和应用现状,对船舶气层减阻技术面对的问题和未来发展方向进行了展望。