水产养殖物联网的应用评价方法

构建科学合理的水产养殖物联网应用评价指标体系和评价方法,是保证水产养殖物联网系统发挥最大能效的基础。为解决指标设置随意、冗余、交叉及技术指标过剩的问题,该文构建了指标筛选模型,将水产养殖物联网应用评价指标体系从40个优化到14个,用35%的指标表达了88.45%的信息,保证了指标体系的完备性和简洁性。同时,基于模糊评价法构建了水产养殖物联网应用评价模型,可对水产养殖物联网应用水平进行总体评价以及功能、性能、效益方面的评价。最后,以江苏宜兴河蟹养殖物联网和广东湛江南美白对虾养殖物联网为实例进行了验证,宜兴物联网的评价结果为优,而湛江物联网的评价结果为良,与实际情况相符,表明该研究构建的指标体系科学合理,评价方法可行,可为水产养殖物联网应用评价提供参考。     

中国土壤环境质量标准中重金属指标的筛选研究

我国土壤重金属污染问题十分严重,但目前国家的土壤环境质量标准已不适应当前土壤环境管理的需求,在指标体系上主要体现在重金属污染物项目过少,对一些新出现的污染问题无法有效监管。本研究通过深入调研美国、加拿大、荷兰、德国、澳大利亚、日本、中国台湾和香港等发达国家和地区的土壤环境标准,并将他们的重金属指标与我国现行的土壤环境质量标准中的重金属指标进行系统比较分析,提出我国土壤环境质量标准中重金属指标的修订建议。主要是要补充六价铬、有机汞等高毒害重金属价态和形态的标准;新增铍、锑、铊、钒等新型重金属污染物的土壤环境质量标准;同时,结合石灰(岩)土高背景区土壤,探索建立基于有效性的土壤重金属浸提态标准体系;为实现我国土壤重金属污染的风险管理提供科学依据。     

Evaluation of soil extractants for silicon availability for sugarcane

Adequate evaluation and interpretation of silicon (Si) phytoavailability in soil is a key to fertilizer recommendation. This study was conducted to determine the effect of soil texture on the choice of Si extractant, and provide baseline data on the relationship between extractable Si and sugarcane Si accumulation. The effects of soil texture and extractant solutions of Si were investigated on soil of nine areas of sugarcane cultivation. Si contents in clayey soils were higher than in sandy soils only in the extraction with standard calcium chloride, acetic acid, potassium chloride (KCl), and sodium acetate buffer. Other extractants failed to reveal differences in the Si availability among the three soil textures. The choice of the extractant should consider soil texture for the determination of adequate Si contents in soils planted with sugarcane, and the extractants that proved to be more efficient in the three soil textures was acetic acid and KCl.     

Recommendations for preparing test samples for AOAC collaborative studies of microbiological procedures for foods

Preparation of test samples for microbial collaborative studies poses problems not encountered in studies on chemical analytes. For Associate Referees who are considering a collaborative study of a microbiological procedure for food analysis, these problems have not been adequately addressed. Types of contamination (natural or artificial), number of test samples required, analyte selection, proper controls, and container selection are addressed herein. The discussion is a supplement to the guidelines contained in the Handbook for AOAC Members.     

Laboratory evaluation of a model for soil crumbling for prediction of the optimum soil water content for tillage

A model for soil crumbling, called the capillary crumbling model (CCM) was introduced by Aluko and Koolen [Aluko, O.B., Koolen, A.J., 2000. The essential mechanics of capillary crumbling of structured agricultural soils. Soil Till. Res. 55, 117–126]. According to the CCM, the optimum soil water content for tillage (θ_OPT) may be defined as the water content at which the capillary bonding strength between aggregates is minimum. The objective of this study was to evaluate the CCM for the arable layer of 10 agricultural soils (sandy loam to clay textures) from semi-arid regions in western Iran. The results were compared with conventional soil workability limits such as 0.85 of the soil plastic limit (0.85θ_PL), Proctor critical water content (θ_Proctor), 0.6 or 0.7 of water content at matric suction of 50 hPa (0.6–0.7θ_50 hPa), and the Kretschmer optimum water content (θ_Kretschmer = θ_PL − 0.15(θ_LL − θ_PL)) where θ_LL is the soil liquid limit. Repacked soil cores were prepared from intact soil aggregates (0.50–4.75 mm) to 0.9 of the critical bulk density (to represent the soil conditions before tillage). Tensile strength and matric suction of the cores were determined at different soil water contents obtained by slow drying. The CCM provided evidence for the physics and mechanics of crumbling in the studied soils. It revealed that effective stresses are the dominant inter-aggregates forces, at least for the wet range of soil water content. A fall in strength of inter-aggregate bonds (i.e. tensile strength) was recorded due to water emptying from structural pores in a narrow range of matric suction (h_OPT) which was consistent with the model. With increasing soil organic matter and clay contents the fall became more distinct, indicating increased structural stability. The θ_OPT values determined by the CCM were found in the h_OPT range 551–612 hPa corresponding to 0.91–0.79θ_PL, which was in agreement with published values for the soil workability limit. Negative correlations between h_OPT and clay and organic matter contents clearly confirmed the increasing effect of soil structure on the enlargement of inter-aggregate pores. High correlations were observed between θ_OPT and 0.85θ_PL, θ_Proctor or 0.7θ_50 hPa. The results showed that the CCM might be recommended as a physically based method for the determination of θ_OPT. Considering the 1:1 relationships between θ_OPT and 0.85θ_PL or θ_Proctor, and easy determination of θ_PL and θ_Proctor, use of these indices is recommended in situations where the CCM is not applicable.     

温室透光覆盖材料流滴性测试方法

作为温室透光覆盖材料的塑料薄膜的流滴性日益受到关注，为此，已开发出各种无滴膜、无滴板，以改善温室透光覆盖材料的流滴性。但国内外对材料流滴性的监测与判断规则却很不统一，给温室用户带来了困难。该文分析了目前几种常用的流滴性检测方法的原理及其适用性，在此基础上，结合温室生产的实际条件，提出在15°～30°倾斜面上形成露滴后，材料表面凝结水滴面积占整个测试面积比例的检测方法——倾斜面上滞留水滴面积比法，并通过对塑料薄膜和聚碳酸酯板的分析测试，提出了将材料表面上计算水滴滞留面积小于10%作为透光覆盖材料流滴性的判别标准，为标准化检测覆盖材料的流滴性提供了依据。     

Method for Preparation of Nutrient-depleted Soil for Determination of Plant Nutrient Requirements

ABSTRACT

Research for nutrient optimization and crop nutrient use efficiency requires precise control on soil nutrient status. While nutrient-depleted soils are preferable to artificial soils or hydroponics, reliable and affordable methods for nutrient removal are lacking. We report the systematic standardization and validation of a simple method to wash soil with purified deionized water for the removal of nutrients such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and organic carbon. Sandy soil was washed with RO water (1:1, w/v) followed by several washes with Type 1 ultrapure water (2:1, w/v) and tested after each wash for the removal of organic carbon, N, P, K, and Ca. After seven washes, total dissolved solids (TDS) were reduced to 5 ppm, conductivity to 10 µS, organic carbon content was reduced by 78%, while N by 19.5%, P by 30%, K by 48% and Ca by 29%. Two genotypes of rice were grown for full life cycle under normal and low N fertilizer (urea) levels to demonstrate that soil depleted with nutrients by our method supports normal plant growth in the greenhouse and allows experiments impossible under field conditions. Precise control on the nutrient status of the soil by our method also helped demonstrate yield differences between genotypes and N regimes and also that higher grain yields can be obtained with low nitrogen (N) input. Thus, our method facilitates better design of experiments for precise determination of nutrient requirements for crop growth and nutrient use efficiency.     

土壤养分的低成本速测技术

本文论述了测土施肥必须遵循经济规律,强调测土施肥必须适合我国国情,提出了以常规分析技术为后盾以速测技术为主体的测土施肥技术路线;文章还论述了土壤养分速测技术,提出了推广速测技术必须解决的观念问题、技术问题和服务体制问题.     

New indicator for classification of agroclimatic conditions for the cultivation of catch crops

The realization of the benefits of stubble catch crops (CC) cultivated after the harvest of the main crop requires the ability to produce substantial amounts of biomass before the onset of winter. The growth and biomass production of CC is primarily determined by the time period of sowing and weather conditions of the site. The construction of a new indicator of agroclimatic conditions for the cultivation of CC is described. This indicator includes the possible time period for CC sowing according to the harvest time of the preceding main crop, temperature, and water conditions for emergence and growth. The termination of growth due to low temperatures is considered. The assumptions used for the construction of the indicator, and the relationships to CC biomass were validated with data from field experiments. The resulting maps of regions in the Czech Republic with similar indicator values for three groups of CC differing in temperature demands are shown.     

山地果园蓄电池驱动单轨运输机传动系统设计

为解决将传统的蜗轮蜗杆传动机构应用于山地果园蓄电池驱动单轨运输机所带来的机械效率低的问题,该文设计了一种基于蜗轮蜗杆的双路传动链传动系统,该系统采用电动机为动力源,通过蜗轮蜗杆传动链和链条传动链两路并联传动链传递动力;两路传动链之间相互独立,根据运输机的运动状态,运用STM32内嵌控制程序对电磁离合器状态进行切换.文中分析了该系统的传动原理、关键零部件设计及机械传动效率,设计输出转速为44~131.18 r/min.采用尤奈特MY1020ZXF-75048 V电机作为动力源,4个12V40AH天能蓄电池串联作为能源,由NMRV040减速器(海格尔控股有限公司)、超越离合器与各型链轮组成双路并联传动链,并运用功率流分析法得出该系统平地与上坡运行状态下输出扭矩为44.352 N·m、输出转速为86.318 r/min、输出功率为609.31 W;下坡与反向运行状态下输出扭矩为105.760 N?m、输出转速为28.953 r/min,输出功率为487.342 W.结果表明,该系统结合了链传动的高效性与蜗轮蜗杆传动的自锁优势,在平地与上坡运行中理论机械效率为81.2%,下坡与反向运行中理论机械效率为60.5%.该研究可为山地果园蓄电池驱动单轨运输机提升机械效率提供参考.     

拖拉机双离合器自动变速器换挡品质评价指标

针对双离合器自动变速器拖拉机在田间高负载作业工况下进行换挡时,原换挡品质评价指标不能充分考察对性能的影响,提出了变速器输出转矩传递系数和变速器输出转矩2个评价指标。归纳了奇数挡和偶数挡离合器接合与分离时序对换挡品质影响规律,建立了拖拉机DCT换挡动力学模型和换挡品质仿真模型。以东方红1804拖拉机为研究对象,对其犁耕工况进行了仿真分析,结果表明:当离合器油压上升滞后时间分别为0、0.1及0.2 s时,对应的变速器最小输出转矩传递系数分别为0.42、0.36及0.12,变速器最小输出转矩分别为2 257、1 932及725 N·m,产生的动载荷逐渐增大,拖拉机动力性变差;提出的2个换挡品质评价指标可较好地对换挡过程中产生的动载荷和拖拉机动力性进行评价,对原换挡品质评价指标进行了补充,完善了拖拉机DCT换挡品质评价体系。该研究为拖拉机双离合器自动变速器换挡控制策略制定提供了理论依据。     

A quantitative method for evaluating the importance of marine areas for conservation of birds

Objective criteria are needed for ranking marine sites when examining candidate areas for protection measures. We suggest a Marine Classification Criterion (MCC) which allows the application of the widely used Ramsar 1% criterion for wetlands for seabirds with clustered distribution in offshore habitats. The maximum size of an area considered to be internationally important has not been defined by the Ramsar Convention. Terrestrial and coastal sites generally have obvious hydrological or physical boundaries, whereas such boundaries are less obvious at sea. The smallest unit which would pass the demands set by the MCC is 1% of the bio-geographic population of a particular species concentrated in an area (site) supporting a density exceeding a value equivalent of four times the average density of the species in the investigated regional sea. The effect of choosing smaller or larger reference densities is tested. The results indicate that the chosen threshold density is a suitable requirement for the inclusion of the most important areas for seabird species with at least 25% of their bio-geographic population occurring in the studied regions of the North Sea and the Baltic Sea. The test cases indicate that provided the MCC is based on geo-statistical analyses of un-biased survey data the boundaries of areas holding large concentrations of seabirds can be estimated with confidence. The MCC could be used to identify concentrations of seabirds and other marine animals of conservation priority and to rank marine areas by their cumulative importance to different species.     

Methodological alternatives for calculation of enrichment factors used for assessment of topsoil contamination

Purpose

The research is aimed at comparison of different enrichment factors (EFs) calculated for potentially harmful chemical elements (PHEs) basing on topsoil data from Klaip?da with geological differences between two areas, choice of the reference elements (REs), consideration of the expediency and efficiency of normalisation, the influence of PHE and RE background or upper threshold values on the estimated contamination level of 50 schoolyards and the arising problems, i.e. which PHE should be normalised.

Materials and methods

Composite topsoil samples taken in 50 schoolyards and 28 football fields from 0 to 10-cm depth were air-dried, sieved to <1 mm, milled and analysed for total contents of major elements and As, Ba, Cr, Cu, Mn, Mo, Ni, Pb, Sn, U, V and Zn by energy-dispersive X-ray fluorescence and of Ag and Co by optical atomic emission spectrophotometry. Simple EFs in schoolyards were calculated normalising by concentration factor (CF) of Fe, while complex EFs normalising by weighted average of Al, K and Ti concentration factors (WACFs).

Results and discussion

The variability of RE is shown with significant differences between sandy western and loamy eastern areas and lower differences between schoolyards and football fields. The highest effectiveness of normalisation, i.e. the number of sites where WACF > 1 or CF > 1, is when RE background values for schoolyards differentiated for each area are selected. The formulas for the ratio of different EFs demonstrate that (1) for Co, Ba, Mn, Mo, Pb and Cu, the upper threshold-type EFs exceed the background-type EFs; (2) there is the tendency to obtain lower EFs for the greater part of PHE when using differentiated background of PHE and RE. The problems of estimation of the background of some PHE and the expediency of their normalisation are discussed.

Conclusions

The recommendations are (1) to explore the variability of RE in the urban territory and to find out if there are areas with significant differences in RE content, in this case try to estimate the differentiated background values of RE and PHE, because respective EFs are usually lower; (2) for more effective normalisation, to use background values of RE which correspond to the object of assessment; (3) not to use upper threshold-type EFs; (4) to be careful with interpretation of EFs for those PHEs which have significant negative correlation with RE.

     

油菜精量联合直播机气力排种系统性能和参数建模

为了了解油菜精量联合直播机气力排种系统工作参数及排种性能对油菜直播机作业性能的直接影响,该文应用JPS-12排种器性能检测试验台及自行研制的气力式油菜精量排种检测系统,开展了气力排种系统排种器单体负压流量与压强、系统各负压支路输气管压强及系统总负压输气管流量的试验,构建了基于系统总负压输气管流量与各支路输气管流量的神经网络模型,得出了系统总负压流量与风机转速、正压泄气孔大小的关系式及系统各支路输气管压强与流量的转换关系模型;同时以排种系统各行排量一致性变异系数＜5%、各排种器单转排量＞36粒等为约束方程,建立了以风机转速、排种轴转速及正压泄气孔大小为变量的整数规划模型,研究表明,所建立的系统工作参数及排种性能模型,对排种系统的性能优化与结构改进具有重要的理论价值和实际指导意义。     

蔬菜嫁接苗高速切割装置设计

针对现有嫁接机存在技术不成熟、价格较高、难以大规模推广应用的问题,提出一种采用高速蔬菜苗切割输送装置配合人工嫁接的新型嫁接模式。蔬菜苗高速切割输送装置包括穴盘输送装置、拨苗装置、切割装置和蔬菜苗输送装置等。根据切割装置结构和工作原理,分析了穴盘输送速度、拨苗轮转速和切割频率之间的关系,并进行了试验研究。试验结果表明:切割装置采用成排连续切割的方式,其蔬菜苗切割效率达到37 000株/h,能够满足嫁接流水线37个人工嫁接工位的用苗需求,达到了30工位的设计要求;刀具切割频率、拨苗轮转速需要匹配穴盘输送速度才能获得最小伤苗率和最优切割成功率。该装置的研制为规模化嫁接苗的生产提供了一种高效率、低成本的人机协同生产方式。     

农用GPS测试精度分析及提高精度方法的研究

通过对GPS测试误差的分析，提出了GPS定点测量坐标是由位置漂移数据与正态分布数据相互叠加而成的。为了分离位置漂移与正态分布相互叠加的数据，用正态剔除法和中心点计算规则，提出了在一定阀值λ下计算定点误差半径的方法。针对单点定位误差比较大的特点，提出了用两点相对定位的测量方法来减小定位误差。试验结果表明：当阀值λ=0.7时，单点定位误差在10 m以上，而用两点相对定位来测量时，其误差为1.2 m左右，大大提高了其测量精度。应用表明，在精度要求不是很高的情况下，可采用单点定位测量，在精度要求较高的情况下，可采用两点相对定位来测量。这两种方法均可用在GPS的土地测量、定位和规划。     

A method for assessing the ornithological interest of sites for conservation

A method is described which was used to classify the ornithological interest of more than 3,000 sites in Britain according to their importance for conservation. Although extremely wide, the range of ornithological interest could be described by three site attributes: population size, diversity and rarity. For any site, quantitative criteria enabled each attribute to be assessed separately in terms of five levels of conservation importance: international, national, regional, county and local. Each site was assigned to the highest level of importance derived from the application of the criteria to the ornithological data. This standardised classification identifies priority sites for conservation planning purposes and it is suggested that it could form a basis for techniques of making detailed comparisons of site quality.     

根系调查取样点数确定方法的研究

根系是植物与外界环境进行物质和能量交换的场所，其分布特征反映了植物对环境的利用程度，随着科学的发展和技术的进步，人们对根系的研究也逐渐从定性走向定量，科学的根系调查方法是进行根系定量研究的关键。在已有的根系调查资料的基础上，应用数量统计的方法，对应用土钻法进行根系调查取样所需要的样点数进行了计算和分析，结果表明，应该按照不同立地，不同取样范围进行根系调查，根据调查的需要和实际状况，确定不同取样范围内所需要的取样点数，并对1／4样圆法的进行了改政和修订，提出了一种新的野外取样的方法。     

农业可持续发展模式设计的自然资源评价方法初探

在农业可持续发展模式设计中通过进行以经济价值为表征的自然资源持续性评价,有利于变自然资源的无偿使用为有偿使用,保持农业自然资源的生产能力。对资源经济价值评价理论与方法进行了集中分析,并以资源折旧法对拜泉县试验小区数据进行了运算分析,证实了该方法的有效性。