配方施肥对小麦生长发育和经济效益的影响

[目的]比较测土配方行动提出的小麦施肥方案在阜南县不同乡镇小麦生长和产量效应。[方法]选择10个试验点,设置空白对照、农民常规施肥和配方施肥共3个处理,小麦成熟期采集植株样品,考察小麦生长发育情况和经济效益。[结果]配方施肥对小麦生长发育具有明显的促进作用,籽粒产量较空白对照和农民常规施肥分别增长37.9%~669.9%和6.1%~23.1%,平均提高120.3%和4.7%,配方施肥比空白对照增收6 018元/hm2,施肥产投比达1.87~6.48。[结论]配方施肥方案能有效促进小麦生长发育,但是较农民常规施肥优势不明显,需要进一步改进和提高。

LMU弹性缓冲系统配方设计研究

LMU竖向缓冲件(以下简称VE)对橡胶材料有着严苛的性能要求,产品压缩比高达30%以上,且对耐老化返原和耐撕裂性能也有较高要求。国产化的LMU缓冲件示范应用于文昌9-2/9-3CEP组块浮托安装项目,其中VE的压缩比达45%、制品厚度大、硫化时间长和特殊的设计结构等因素要求胶料具有100%定伸低、拉伸强度高、撕裂强度高、耐返原性能好、压缩永久变形低等特点,本文介绍了胶料进行的一些配方优化方案。

煤基甲醇制烯烃企业循环水系统水处理药剂筛选及应用

煤化工废水经处理后回用到循环冷却水系统,对节能降耗有重要意义。介绍了淮南某煤基甲醇制烯烃企业污水处理场的工艺流程,通过静态阻垢缓蚀试验和动态模拟试验,筛选出适合循环水处理系统的药剂及配方方案。生产实践表明:两种药剂A和B配合投加质量分数为80×10^(-6)和25×10^(-6)时,可确保企业循环水水质符合要求。

浅谈高强混凝土的质量控制

高性能混凝土是近年来混凝土材料发展的一个重要方向,所谓高性能:是指混凝上具有高强度、高耐久性、高流动性等多方面的优越性能。从强度而言,抗压强度大于C60的混凝土即属于高强混凝土,提高混凝土的强度是发展高层建筑、高耸结构、大跨度结构的重要措施。采用高强混凝土,可以减小截面尺寸,减轻自重,因而可获得较大的经济效益,而且,高强混凝土一般也具有良好的耐久性。

Joint subcarrier and power allocation with threshold in cooperative multiuser networks

In this paper, we investigate a resource allocation issue in OFDMA-based decode-and-forward cooperative multiuser networks and propose joint subcarrier and power allocation schemes. The optimal solution of this combinable allocation shows high computational complexity, so we allocate subcarriers and power separately. At firstly, we distribute subcarriers to relays and users under the assumption of equal power distribution. Here, we propose an equal capacity increment （ECI） allocation strategy to achieve tradeoff between total throughput and fairness. To further improve the system performance, we introduce threshold into ECI strategy, named ECI strategy with threshold （ECI-T）, where subcarriers with bad performance are prevented from transmitting. Subsequently, a water-filling method is adopted to distribute the power to cooperative links in order to fully utilize the limited power. Simulation results show that system performance of the proposed schemes is significantly enhanced compared with an existing resource allocation scheme. Besides, the resource allocation schemes with the water- filling method notably outperform schemes with equal power allocation.

Study on the Concept of Per Capita Cumulative Emissions and Allocation Options

Global long-term emission reduction targets need well defined options for equitable allocation of greenhouse gas emissions. Scholars from developing countries put forward the concept of equitable per capita cumulative emission rights. There are four possible operational definitions resulting from this concept. These potential options for allocation of emission rights are expressed with mathematical equations. Through simple simulation, this paper reveals the advantages, disadvantages and characteristics of each option.

基于农村土地承包经营权确权数据的测土配方施肥方案手机短信发布技术研究

测土施肥方案短信发布是施肥方案传达最为经济、便捷和易接受的方式,农村土地承包经营权确权数据是全国性的农村土地经营权最为翔实的数据,其地块编码等字段有着法定性、唯一性、终生性的特点。本研究利用农村土地承包经营权确权数据的特点,为测土配方施肥方案手机短信发布提供支持,重点阐述了基于农村土地承包经营权确权数据的测土配方施肥方案短信发布技术的四大关键环节。结果表明:基于农村土地承包经营权确权数据的测土配方施肥方案短信发布技术理论和技术上切实可行,实现了网络全覆盖、空间全覆盖的测土配方施肥方案的发布技术、扩展了测土配方施肥方案短信平台推广应用空间边界和时间边界。为测土配方施肥方案发布提供了新的思路和技术支持,对测土配方施肥项目的更加深入推广应用有着重要意义。

Effects of wind input and wave dissipation formulations on the steady Ekman current solution

The effects of different wind input and wave dissipation formulations on the steady Ekman current solution are described. Two formulations are considered: one from the wave modeling(WAM) program proposed by Hasselmann and Komen and the other provided by Tsagareli and Babanin. The solution adopted for our study was presented by Song for the wave-modifi ed Ekman current model that included the Stokes drift, wind input, and wave dissipation with eddy viscosity increasing linearly with depth. Using the Combi spectrum with tail effects, the solutions are calculated using two formulations for wind input and wave dissipation, and compared. Differences in the results are not negligible. Furthermore, the solution presented by Song and Xu for the eddy viscosity formulated using the K-Profi le Parameterization scheme under wind input and wave dissipation given by Tsagareli and Babanin is compared with that obtained for a depth-dependent eddy viscosity. The solutions are further compared with the available well-known observational data. The result indicates that the Tsagareli and Babanin scheme is more suitable for use in the model when capillary waves are included, and the solution calculated using the K-Profi le Parameterization scheme agrees best with observations.

Genetic approach for Cell-by-Cell dynamic spectrum allocation in the heterogeneous scenario

In this paper,a genetic algorithm (GA) is investigated to deal with cell-by-cell dynamic spectrumallocation (DSA) in the heterogeneous scenario with temporal and spatial traffic demand changes,whichis also known as a difficult combinatorial optimization problem.A new two-dimensional chromosome encodingscheme is defined according to characteristics of the heterogeneous scenario,which prevents forminginvalid solutions during the genetic operation and enables much faster convergence.A novel randomcoloring gene generation function is presented which is the basic operation for initialization and mutationin the genetic algorithm.Simulative comparison demonstrates that the proposed GA-based cell-by-cellDSA outperforms the conventional contiguous DSA scheme both in terms of spectral efficiency gain andquality of service (QoS) satisfaction.

Method for determination of allocable water during formulation of water allocation scheme

The determination of allocable water is one of the most important stages during the process of formulating water allocation scheme.The selection of appropriate allocable water is the prerequisite and fundament for developing a reasonable water allocation scheme.Based on the summary and analysis of international water allocation practice,this paper has distilled three attention-worth issues concerning the determination of allocable water.In addition,this paper has also proposed a general method for the determination of allocable water and illustrated this method in detail.It is hoped that through providing a general and feasible method for determining allocable water,a fundament could be established for the consultation of water allocation process among different stakeholders,promoting the integrated management of river basins.

An Authenticated Group Key Distribution Scheme for Wireless Sensor Networks

In wireless sensor networks （WSNs）, group key distribution is the core of secure communications since sensor nodes usually form groups and cooperate with each other in sensing data collection and in-network processing. In this paper, we present a scalable authenticated scheme for group key distribution based on a combinatorial exclusion basis system （EBS） for efficiency and one-way hash chains for authentication. The proposed scheme guarantees a lightweight authenticated group key updating procedure and is efficient in terms of storage, communication and computation overheads.

Highly efficient terahertz generation from periodically-poled RbTiOPO_4

Terahertz(THz) generation by periodically-poled RbTiOPO_4(PPRTP) with a quasi-phase-matching scheme based on cascaded difference frequency generation(DFG) processes is theoretically analyzed. The cascaded Stokes and anti-Stokes interaction processes are investigated from coupled wave equations. The THz intensities and quantum conversion efficiency are calculated. Compared with that of non-cascaded DFG processes, the THz intensity in 7-order cascaded DFG processes is increased to 2.95 times. The quantum conversion efficiency of 149.9% in cascaded processes can be realized, which exceeds the Manley-Rowe limit.