不同施肥模式对大豆生长季土壤有效氮供给的影响

为探究施肥模式对潮土区大豆生长季土壤有效氮供给的影响,本研究基于33年长期定位施肥试验,选取4种处理:不施肥(CK)、施氮磷钾化肥(NPK)、氮磷钾化肥+秸秆还田(SNPK)与氮磷钾化肥+有机肥(MNPK),测定分析大豆生长季内土壤铵态氮(NH_(4)^(+)-N)、硝态氮(NO_(3)^(-)-N)、微生物量氮、可溶性有机氮含量的变化动态,以及参与土壤氮素转化的有机氮矿化酶活性、氨化作用强度与硝化潜势。结果表明,化肥与秸秆或有机肥配施可提高土壤全氮、有机碳、微生物量碳和可溶性有机碳含量,这对土壤脲酶、酰胺酶、蛋白酶和N-乙酰-β-D-葡萄糖苷酶活性及氨化作用强度和硝化潜势的提升有不同程度的促进作用。土壤NH_(4)^(+)-N含量与脲酶和蛋白酶活性呈极显著正相关,与酰胺酶活性呈显著正相关;NO_(3)^(-)-N含量与氨化作用强度、硝化潜势呈极显著正相关。SNPK、MNPK处理下的土壤微生物量氮和可溶性有机氮含量均高于NPK、CK处理。潮土可溶性有机氮含量与大豆地上部氮素吸收呈极显著正相关,并最终影响大豆生长;成熟期SNPK、MNPK处理下的大豆地上部生物量均高于CK、NPK处理。综上所述,化肥与秸秆或有机肥配施可通过提高全氮、有机碳和活性有机碳含量正向调控土壤氮素转化微生物作用强度与酶活性,提高土壤有效氮供给能力,促进大豆生长。本试验结果可为潮土区合理施肥提供理论依据。

RELIABILITY ANALYSIS FOR A REPAIRABLE PARALLEL SYSTEM WITH TIME-VARYING FAILURE RATES

To solve a real problem:how to calculate the reliability of a system with time-varying failure rates in industry systems,this paper studies a model for the load-sharing parallel system with time-varying failure rates,and obtains calculating formulas of reliability and availability of the system by solving differential equations.In this paper,the failure rates are expressed in polynomial configuration.The constant,linear and Weibull failure rate are in their special form.The polynomial failure rates provide flexibility in modeling the practical time-varying failure rates.

Comparison of availability and reliability among different combined-GNSS/RNSS precise point positioning

With emergence of the BeiDou Navigation Satellite System(BDS), the Galileo Satellite Navigation System(Galileo), the Quasi-Zenith Satellite System(QZSS)and the restoration of the Global Navigation Satellite System(GLONASS), the single Global Positioning System(GPS) has been gradually expanded into multiple global and regional navigation satellite systems(multi-GNSS/RNSS). In view of differences in these 5 systems, a consolidated multi-GNSS/RNSS precise point positioning(PPP) observation model is deduced in this contribution. In addition, the performance evaluation of PPP for multi-GNSS/RNSS is conducted using a large number of the multi-GNSS experiment(MGEX) station datasets. Experimental results show that multi-GNSS/RNSS can guarantee plenty of visible satellites effectively. Compared with single-system GPS, PDOP, HDOP, and VDOP values of the multi-GNSS/RNSS are improved by 46.8%, 46.5% and 46.3%, respectively. As for convergence time, the static and kinematic PPP of multi-GNSS/RNSS are superior to that of the single-system GPS, whose reliability, availability, and stability drop sharply with the increasing elevation cutoff. At satellite elevation cutoff of 40 °, the single-system GPS fails to carry out continuous positioning because of the insufficient visible satellites, while the multi-GNSS/RNSS PPP can still get positioning solutions with relatively high accuracy, especially in the horizontal direction.

BUFFER DIMENSIONING FOR RATE-BASED CONTROL IN ATM NETWORK

Available Bit Rate (ABR) service has been developed to support data applications to asynchronous transfer mode (ATM) networks.Since a ratebased feedback flow control mechanism has been selected as a standard by ATM Forum,buffering becomes an issue that needs intensive study.In this paper,the queuing performance in a switch is studied in detail.It is theoretically proven that the goals of no cell loss and full utilization of link capacity can be achieved by choosing an appropriate buffersize and threshold of the switch buffer which is supported by our simulation results of a complex network.

Modeling the Failure Rate of a Standby Multi-Component System and Improving Reliability

Evaluating the reliability of a system requires knowledge of the failure modes to which it is subjected. Complex topology systems generally require a high level of availability, which is a function of the arrangement of elements (components) in the system. To avoid serious failures for such complex systems, recourse can be had to the redundancy techniques available in the literature. These techniques help to improve system reliability, without affecting the reliability of system components. This paper is interested in the proposal of a model for evaluating the failure rate of a standby multi-components system and in improving the reliability of mechanical systems, arranged in a topology (series, parallel, or mixed).

Optimum Maintenance and Availability of Series Systems Subject to Imperfect Repair

Optimum maintenance and availability of a series system whose components are subject to imperfect repairs are studied in this paper. Imperfect corrective maintenance is treated in a way that after it the life of each component in the system will be decreased to a fraction of its immediately previous one and the repair time will be increased to a multiple of the one immediately preceding it, where successive failure free times are independent and so are successive repair times. Under such an assumption, the limiting system availability, mean time between system failures or repairs are derived based on some related results. A numerical example is presented to compare with Barlow and Proschan's availability model. Two classes of maintenance cost models are proposed and the optimum maintenance policies are also discussed for series system with n components in this paper.

我国籽实和饲草大麦土壤有效磷丰缺指标和推荐施磷量

为了给我国大麦测土施磷提供科学依据,采用“零散实验数据整合法”和“养分平衡-地力差减法新应用公式”,开展了我国大麦土壤有效磷丰缺指标和推荐施磷量研究.结果表明,我国大麦土壤有效磷第1~8级丰缺指标依次为≥40.7、24.2~40.7、14.4~24.2、8.6~14.4、5.1~8.6、3.0~5.1、1.8~3.0和<1.8 mg/kg.当磷肥利用率15%~35%时,目标产量3~7.5 t/hm~2籽实大麦第1~8级土壤推荐施磷量分别为0、9~50、17~100、26~150、34~200、43~250、51~300和60~350 kg/hm~2;目标产量6~15 t/hm~2干草大麦第1~8级土壤推荐施磷量依次为0、9~50、17~100、26~150、34~200、43~250、51~300和60~350 kg/hm~2;目标产量15~45 t/hm~2青贮大麦第1~8级土壤推荐施磷量分别为0、7~51、15~102、22~153、29~204、36~255、44~306和51~357 kg/hm~2.本研究建立了我国籽实和饲草大麦土壤有效磷丰缺指标推荐施肥系统,为我国大麦测土施磷奠定了科学基础.

我国籽实和饲草燕麦土壤有效磷丰缺指标与推荐施磷量初步研究

为了给我国燕麦测土施磷提供科学依据,本研究采用“零散实验数据整合法”和“养分平衡-地力差减法新应用公式”,开展了我国燕麦土壤有效磷丰缺指标与推荐施磷量研究。结果表明,我国燕麦土壤有效磷第1~8级丰缺指标依次为≥45、24~45、12~24、6.2~12、3.2~6.2、1.7~3.2、0.9~1.7和<0.9mg/kg。当磷肥当季利用率为15%~35%时,目标产量1.5~6.0t/hm^(2)籽实燕麦第1~8级土壤推荐施磷量分别为0、4~40、9~80、13~120、17~160、21~200、26~240和30~280kg/hm^(2);目标产量4.5~15t/hm^(2)饲草燕麦第1~8级土壤推荐施磷量依次为0、6~50、13~100、19~150、26~200、32~250、39~300和45~350kg/hm^(2)。本研究建立了我国籽实和饲草燕麦土壤有效磷丰缺指标推荐施肥系统,为我国燕麦测土施磷奠定了科学基础。

中国三大棉花种植区域土壤速效钾丰缺指标及推荐施钾量研究

为给西北内陆棉区、长江流域棉区和黄河流域棉区棉花的钾肥施用提供科学依据,采用“零散实验数据整合法”“反正弦-对数矫正模型”以及“养分平衡-地力差减法”,开展了上述三大棉区棉花土壤速效钾丰缺指标和推荐施钾量研究。结果表明,中国三大棉区土壤速效钾丰缺指标均可划分出5级,西北内陆棉区第1~5级丰缺指标为≥418、166~418、111~166、80~111和<80 mg/kg;长江流域棉区第1~5级丰缺指标为≥357、128~357、81~128、56~81和<56 mg/kg;黄河流域棉区第1~5级丰缺指标为≥213、129~213、102~129、85~102和<85 mg/kg。三大棉区土壤速效钾临界值分别为166.0、127.2和128.4 mg/kg。当钾肥当季利用率为50%,籽棉(皮棉)目标产量为2.5~9.0(1.0~3.6)t/hm^(2)时,第1~5级土壤的推荐施钾量依次为0、30~108、60~216、90~324和120~432 kg/hm^(2)。

我国籽实和饲草燕麦土壤钾素丰缺指标与推荐施钾量初步研究

为了给我国燕麦测土施钾提供科学依据,本研究采用“零散实验数据整合法”和“养分平衡-地力差减法新应用公式”,开展了我国燕麦土壤钾素丰缺指标与推荐施钾量研究。结果表明,我国燕麦土壤速效钾第1~3级丰缺指标依次为≥258、117~258和<117mg/kg,全钾第1~4级丰缺指标依次为≥31、21~31、11~21和<11 g/kg。当钾肥当季利用率40%~60%时,目标产量1.5~6.0t/hm^(2)籽实燕麦第1~4级土壤推荐施钾量分别为0、10~60、20~120和30~180kg/hm^(2);目标产量4.5~15t/hm^(2)饲草燕麦第1~4级土壤推荐施钾量依次为0、18~90、36~180和54~270kg/hm^(2)。本研究初步建立了我国籽实和饲草燕麦土壤钾素丰缺指标推荐施肥系统,为我国燕麦测土施钾奠定了科学基础。

我国葡萄土壤有效磷丰缺指标和适宜施磷量研究

为建立我国葡萄测土推荐施磷系统,本研究采用作物土壤养分丰缺指标推荐施肥系统研究新方法,探讨了我国葡萄土壤有效磷丰缺指标与适宜施磷量。结果表明,我国葡萄土壤有效磷第1~7级丰缺指标依次为≥95、35~95、13~35、4.5~13、1.7~4.5、0.6~1.7 mg/kg和<0.6 mg/kg。在葡萄目标产量15~60 t/hm^(2)、磷肥利用率15%~35%、土壤有效磷丰缺级别第1~7级情形下,目标产量15、22.5、30、37.5、45、52.5、60 t/hm^(2)的适宜施磷量范围分别为0~120、0~180、0~240、0~300、0~360、0~420、0~480 kg/hm^(2);磷肥利用率35%、30%、25%、20%、15%的适宜施磷量范围依次为0~206、0~240、0~288、0~360、0~480 kg/hm^(2);有效磷丰缺级别第1~7级土壤适宜施磷量分别为0、9~80、17~160、26~240、34~320、43~400、51~480 kg/hm^(2)。

我国甜菜土壤有效磷丰缺指标与适宜施磷量研究

【目的】甜菜是重要的糖料作物,土壤磷素供应和磷肥施用影响甜菜的产量和品质。为此,我们开展甜菜土壤有效磷丰缺指标与适宜施磷量研究。【方法】采用“零散实验数据整合法”建立我国甜菜相对产量与土壤有效磷含量回归方程。以“甜菜”“施肥”“磷”为主题词,在中国知网检索到相关论文44篇,剔除低质量试验数据后,共获得104组包含不施磷和施磷处理甜菜产量数据,及对应的土壤有效磷含量数据,建立不施磷甜菜相对产量与土壤有效磷含量之间的回归方程。参考“土壤养分丰缺分级改良方案”将土壤有效磷含量分为7级,将各节点不施磷甜菜相对产量带入建立的回归方程,计算出每个节点的土壤有效磷含量,作为甜菜土壤有效磷分级指标。采用“养分平衡—地力差减法新公式”,依据目标产量和磷肥利用率,计算了不同丰缺等级土壤的甜菜适宜施磷量。【结果】我国甜菜缺磷处理相对产量与土壤有效磷含量回归方程为:y=14.169 Ln(x)+46.679(R~2=0.3242,n=104,P<0.01)。我国甜菜土壤有效磷由高到低分为7个等级,对应的有效磷含量依次为≥44、22~44、11~22、6~11、3~6、1.5~3和<1.5 mg/kg。当甜菜目标产量为30~90 t/hm^(2)、磷肥利用率为15%~35%时,有效磷第1~7级土壤的适宜施磷量分别为0、13~90、26~180、39~270、51~360、64~450、77~540 kg/hm^(2)。【结论】鉴于收集采用的数据样本量大且来源于高质量试验,本研究建立的我国甜菜缺磷处理相对产量与土壤有效磷含量之间的回归方程具有很好的可信度,依据该方程确定了土壤有效磷丰缺指标,进而若干目标产量和磷肥利用率下不同丰缺等级土壤的甜菜适宜施磷量得以推荐。

多维度下的国家医保谈判药品配备分析

目的:从药品配备角度分析国家医保谈判药品落地情况,探究落地过程中存在的问题并提出对策建议。方法:收集国家医保服务平台公示的协议期内388种谈判药品在全国的配备数据,从不同地区、机构类型、疾病领域、药品剂型、谈判批次等角度分析国谈药品在定点医药机构的配备品种数、配备率以及可获得率等指标。结果:超50%的被研究药品覆盖了全国30个及以上省份和50%以上的地市级城市,江苏和浙江的国谈药品配备情况较好,西藏、新疆和青海的国谈药品配备情况较差。平均每个省和地市级城市分别配备了330种和209种国谈药品,药品配备率分别为85.0%和53.8%。三线及以下城市的药品平均配备率(49.4%)低于一线城市(87.3%),非省会城市(51.5%)低于省会城市(80.3%)。口服剂型药品、慢性病用药和罕见病用药平均覆盖的零售药店数量高于医疗机构的数量。国谈药品在全国三级医院的平均可获得率非常低,仅为10.2%,肿瘤用药、注射剂型药品以及2018年首谈药品在三级医院的可获得率高于其他类型国谈药。罕见病用药在三级医院和罕见病协作网医院的平均可获得率较低,分别为3.2%和12.8%。结论:国谈药品在全国的落地情况存在品种、病种和地区等维度差异,本文将从零售药店供应、医疗机构临床使用以及企业推广等角度进行具体讨论,并提出对策建议,以期不断优化国谈药品的供应保障。

Examining the Quality Metrics of a Communication Network with Distributed Software-Defined Networking Architecture

Software-Defined Networking(SDN),with segregated data and control planes,provides faster data routing,stability,and enhanced quality metrics,such as throughput(Th),maximum available bandwidth(Bd(max)),data transfer(DTransfer),and reduction in end-to-end delay(D(E-E)).This paper explores the critical work of deploying SDN in large-scale Data Center Networks(DCNs)to enhance its Quality of Service(QoS)parameters,using logically distributed control configurations.There is a noticeable increase in Delay(E-E)when adopting SDN with a unified(single)control structure in big DCNs to handle Hypertext Transfer Protocol(HTTP)requests causing a reduction in network quality parameters(Bd(max),Th,DTransfer,D(E-E),etc.).This article examines the network performance in terms of quality matrices(bandwidth,throughput,data transfer,etc.),by establishing a large-scale SDN-based virtual network in the Mininet environment.The SDN network is simulated in three stages:(1)An SDN network with unitary controller-POX to manage the data traffic flow of the network without the server load management algorithm.(2)An SDN network with only one controller to manage the data traffic flow of the network with a server load management algorithm.(3)Deployment of SDN in proposed control arrangement(logically distributed controlled framework)with multiple controllers managing data traffic flow under the proposed Intelligent Sensing Server Load Management(ISSLM)algorithm.As a result of this approach,the network quality parameters in large-scale networks are enhanced.

Reliability-BasedModel for Incomplete Preventive ReplacementMaintenance of Photovoltaic Power Systems

At present,the operation and maintenance of photovoltaic power generation systems mainly comprise regular maintenance,breakdown maintenance,and condition-based maintenance,which is very likely to lead to over-or under-repair of equipment.Therefore,a preventive maintenance and replacement strategy for PV power generation systems based on reliability as a constraint is proposed.First,a hybrid failure function with a decreasing service age factor and an increasing failure rate factor is introduced to describe the deterioration of PV power generation equipment,and the equipment is replaced when its reliability drops to the replacement threshold in the last cycle.Then,based on the reliability as a constraint,the average maintenance cost and availability of the equipment are considered,and the non-periodic incomplete maintenance model of the PV power generation system is established to obtain the optimal number of repairs,each maintenance cycle and the replacement cycle of the PV power generation system components.Next,the inverter of a PV power plant is used as a research object.The model in this paper is compared and analyzed with the equal cycle maintenance model without considering reliability and the maintenance model without considering the equipment replacement threshold,Through model comparison,when the optimal maintenance strategy is(0.80,4),the average maintenance cost of this paper’s model are decreased by 20.3%and 5.54%and the availability is increased by 0.2395% and 0.0337%,respectively,compared with the equal-cycle maintenance model without considering the reliability constraint and the maintenance model without considering the equipment replacement threshold.Therefore,this maintenance model can ensure the high reliability of PV plant operation while increasing the equipment availability to improve the system economy.

荞麦土壤有效磷丰缺指标和适宜施磷量建模

为建立荞麦测土推荐施磷系统,采用作物土壤养分丰缺指标推荐施肥系统研究新方法,开展了荞麦土壤有效磷丰缺指标与适宜施磷量研究。结果表明,荞麦缺磷处理相对产量与土壤有效磷含量回归方程为y=10.352 lnx+58.085,土壤有效磷第1—7级指标依次为>58、>22~58、>8.5~22、>3.5~8.5、>1.2~3.5、>0.5~1.2、≤0.5 mg/kg。当土壤有效磷丰缺级别1—7级、磷肥利用率15%~35%、目标产量0.90~3.75 t/hm^(2)时,第1—7级土壤的适宜施磷量分别为0、4~38、8~75、12~113、15~150、19~188、23~225 kg/hm^(2);磷肥利用率35%、30%、25%、20%、15%的适宜施磷量范围依次为0~96、0~113、0~135、0~169、0~225 kg/hm^(2);目标产量0.90、1.50、2.25、3.00、3.75 t/hm^(2)的适宜施磷量范围分别为0~54、0~90、0~135、0~180、0~225 kg/hm^(2)。

成熟卵子率对常规体外受精后胚胎形成率的影响

目的观察成熟卵子(mature metaphase ovum,MⅡ)率对常规体外受精(in vitro fertilization,IVF)后胚胎形成率及MⅡ卵子利用率的影响。方法回顾性分析空军特色医学中心单腔取卵、常规IVF的408个周期,按MⅡ率分为6组:A组(≥90%)197例,B组(≥80%~90%)105例,C组(≥70%~80%)54例,D组(≥60%~70%)28例,E组(≥50%~60%)14例,F组(<50%)10例。对各组年龄、基础卵泡刺激素、基础窦卵泡、促性腺激素用量和天数、绒毛膜促性腺激素日雌二醇水平、促排方案构成比、获卵数、MⅡ卵子数、双原核(two pronuclears,2PN)率、可移植胚胎率及MⅡ卵子利用率进行比较。结果各组相比患者基本情况、促排方案构成比、促排过程、获卵数之间差异无统计学意义(P>0.05)。2PN率、可移植胚胎数、可移植胚胎率随MⅡ率降低而降低,差异有统计学意义(F=25.530、2.384、8.685,P<0.001、=0.038、<0.001),而MⅡ卵子利用率差异无统计学意义(F=0.316,P=0.903)。A组成胚率(44.33±18.97)%高于其余各组[B组(38.84±17.82)%,C组(36.34±18.21)%,D组(30.45±11.38)%,E组(25.21±11.38)%,F组(20.85±12.68)%],差异均有统计学意义(P=0.011、0.004、<0.001、<0.001、<0.001)。结论单腔取卵、常规IVF周期卵子成熟率与促排方案无关;随着卵子成熟率下降,正常受精率、可移植胚胎率均明显降低,特别是MⅡ率<70%时;但卵子成熟率未影响已成熟卵子质量。

常规体外受精失败后行补救性卵胞浆内单精子注射的应用效果

目的:观察常规体外受精(IVF)失败后行补救性卵胞浆内单精子注射(R-ICSI)的应用效果。方法:回顾性分析2016年1月至2020年12月该院收治的1673个周期的临床资料,按照受精方式不同将其分为IVF组(1042个周期)、R-ICSI组(131个周期)、卵胞浆内单精子注射(ICSI)组(500个周期)。比较三组实验室指标[成熟卵(MⅡ)获取率、受精率、2原核(PN)率、多PN率、优质胚胎率、可用胚胎率]水平、临床结局(妊娠率、活产率)。结果:R-ICSI组MⅡ获取率均低于IVF组与ICSI组,差异有统计学意义(P<0.05);R-ICSI组2PN率低于ICSI组,但高于IVF组,差异有统计学意义(P<0.05);R-ICSI组多PN率低于IVF组,但高于ICSI组,差异有统计学意义(P<0.05);R-ICSI组与ICSI组优质胚胎率、可用胚胎率均低于IVF组,差异有统计学意义(P<0.05);R-ICSI组活产率高于IVF组、ICSI组,差异有统计学意义(P<0.05);三组受精率、妊娠率比较,差异无统计学意义(P>0.05)。结论:IVF失败后行R-ICSI的活产率高于IVF、ICSI;优质胚胎率和可用胚胎率低于IVF;多PN率低于IVF,高于ICSI;2PN率低于ICSI,高于IVF;MⅡ获取率低于IVF和ICSI。

不同条件下土壤中重金属有效态的提取效果及回收率研究

本研究旨在探讨不同实验条件(粒径、浸提剂、标准曲线基体溶液、加标后浸提时间以及土壤类型)对土壤中重金属有效态提取效果及回收率的影响。通过设计一系列实验,对比分析不同条件下的提取效率和回收率,以期为土壤重金属污染治理提供理论依据和实践指导。根据结果显示:粒径10目土壤浸提效果最好,60目其次,100目较差;浸提剂效果HCl最好,DTPA其次,CaCl2几乎没有;曲线基体应匹配相应的基体溶液以减少测试干扰;对于加标后浸提的时间,浸提时间越晚,回收效果越差;土壤类型不同,加标回收率为砂土最好,壤土次之,黏土最差。

航空电子硬件单粒子效应故障率的指标要求探索

航空电子硬件单粒子效应故障率是系统安全性分析过程中的重要基础数据。其指标要求的制定是一个难题。作者基于国际上航空电子硬件单粒子效应故障率计算要求的跟踪梳理分析,研究提出了一些复杂电子硬件单粒子效应故障率的指标要求探索方向,可以为设计师提供参考。