软路由组建企业网

随着我国经济的高速发展,涌现出了大量的中小企业。而在当今这个信息化的时代,企业网络的组建对企业的发展有着十分重要的作用,因此大部分的中小企业都会建设好企业的网络来实现整个企业的信息化。然而中小企业在信息化建设能够投入的资金是非常有限、对于企业网络的后期维护和管理同样面临着专业技术人员缺乏的难题。怎样解决这个问题？即在使用较少资金的同时又能合理地将企业的网络组建起来,并且组建完成之后再后期的管理和维护上不需要非常多的专业技术人员。目前,大部分中小企业采用了软路由组网的方法来解决这个问题。     

基于小波分析的储粮害虫图像去噪研究

以储粮害虫为研究对象,阐述了小波去噪的基本原理和高频系数置零、硬阈值法、软阈值等几种方法,并提出了一种改进的小波阈值去噪方法,比较了这几种方法在粮虫图像去噪上的优缺点。实验结果表明,改进的新阈值方法能更好的去除噪声,收到更好的效果。     

开关电源新技术的应用研究

以功率MOSFET和IGBT为代表的、集高频、高压和大电流于一身的功率半导体复合器件,表明传统电力电子技术已经进入现代电力电子时代,开关电源的工作频率得以大大提高,一些新技术的应用更是进一步提升了开关电源的性能。开关电源拥有更广阔的发展空间和应用前景。     

Incubating superphosphate in ‘dry’soil can reduce its effectiveness

Single superphosphate was incubated for six months at 25°C in soil which had been subject to one of three moisture treatments. These were: dried in a glasshouse, dried at a constant temperature of 25°C, or moist soil. Phosphorus (P) effectiveness was then compared with effectiveness of P from freshly-applied superphosphate using yields of wheat (Triticum aestivum) and triticale (×Triticosecale) tops in pot experiments.Incubation in soil which had been dried at 25°C did not decrease the effectiveness of the P. Incubation in moist soil decreased it to about 20% of the effectiveness of freshly-applied P in one case and to about 50% in the other case. Incubation in soil which had been dried in a glasshouse also decreased its effectiveness. The decrease varied with conditions, but in two cases the P was 70% as effective as freshly-applied P, and in one case only 45% as effective. Presumably sufficient moisture was present in the soil dried in the glasshouse to enable water-soluble P present in the fertilizer to react with the soil.     

Fate of nitrogen fertilizer applied to lowland rice on a Sulfic Tropaquept

A field experiment was conducted on an acid sulfate soil in Thailand to determine the effect of N fertilization practices on the fate of fertilizer-N and yield of lowland rice (Oryza sativa L.). A delayed broadcast application of ammonium phosphate sulfate (16-20-0) or urea was compared with basal incorporation of urea, deep placement of urea as urea supergranules (USG), and amendment of urea with a urease inhibitor. Deep placement of urea as USG significantly reduced floodwater urea- and ammoniacal-N concentrations following N application but did not reduce N loss, as determined from an¹⁵N balance, in this experiment where runoff loss was prevented. The urease inhibitor, phenyl phosphorodiamidate (PPD), had little effect on floodwater urea- and ammoniacal-N, and it did not reduce N loss. The floodwater pH never exceeded 4.5 in the 7 days following the first N applications, and application of 16-20-0 reduced floodwater pH by 0.1 to 0.3 units below the no-N control. The low floodwater pH indicated that ammonia volatilization was unimportant for all the N fertilization practices. Floodwater ammoniacal-N concentrations following application of urea or 16-20-0 were greater on this Sulfic Tropaquept than on an Andaqueptic Haplaquoll with near neutral pH and alkaline floodwater. The prolonged, high floodwater N concentrations on this Sulfic Tropaquept suggested that runoff loss of applied N might be a potentially serious problem when heavy rainfall or poor water control follow N fertilization. The unaccounted-for¹⁵N in the¹⁵N balances, which presumably represented gaseous N losses, ranged from 20 to 26% of the applied N and was unaffected by urea fertilization practice. Grain yield and N uptake were significantly increased with applied N, but grain yield was not significantly affected by urea fertilization practice. Yield was significantly lower (P = 0.05) for 16-20-0 than for urea; however, this difference in yield might be due to later application of P and hence delayed availability of P in the 16-20-0 treatment.     

Available nitrogen in soils and its determination by the ‘Nmin-method’ and by electroultrafiltration (EUF)

Excess nitrogen fertilizer rates are an environmental hazard. To avoid excess rates, the level of available nitrogen in the soil must be known and considered for assessing the nitrogen fertilizer rate. In arable soils nitrate and exchangeable ammonium in the rooting depth of a crop are directly available to plant roots. These two nitrogen forms are recovered with the Nmin method and they are considered in assessing the nitrogen fertilizer rate for arable crops.Besides nitrate and ammonium recovered by the Nmin method from soil samples taken in early spring, a considerable amount of organic soil nitrogen may be mineralized during the growth period and contribute to crop nutrition. The nitrogen mineralization potential can be determined in incubation tests. The absolute quantities of mineralized nitrogen thus obtained, however, are much higher than the mineralization rates under field conditions. It is for this reason that incubation tests have not obtained a major importance for assessing nitrogen fertilizer rates.With the electro-ultrafiltration (EUF) method nitrate, ammonium, and a minor portion of organic soil nitrogen are extracted from a soil suspension. There is experimental evidence that this organic nitrogen (=Norg) is easily mineralizable. Based on field experiments with cereals and maize formulae were established by which the nitrogen fertilizer rate can be calculated. In these formulae nitrate, ammonium and organic nitrogen extracted by EUF are considered.Advantages and drawbacks of the Nmin method and EUF method are discussed.     

地源热泵土壤热物性测试与分析

运用恒热流测试原理自主研发了岩土热物性测试仪,通过现场测试的方法,调整加热管的加热功率、埋管中循环水流量、埋管进出口水温随时间变化规律,利用线热源理论确定了地下岩土的热物性参数。实验表明,土壤初始温度的测量精度对于提高土壤的导热系数是至关重要的,在未扰动的土壤温度以及给定PE管材的条件下,测试时间为50小时左右时,土壤导热系数逐渐趋于稳定,收敛于3.109 W/(m.℃),整个测试过程平均导热系数为3.489W/(m.℃),该结果为地源热泵系统的准确设计提供了依据。     

复合土钉支护技术在深基坑中的应用

该基坑工程地质上存在的主要问题是上层为杂填土和呈流塑态的淤泥,自稳能力极差,还受现场施工条件以及经济因素的限制。本基坑采用的支护方案为:I选用段顶部放坡+粉喷桩+土层锚杆;Ⅱ、Ⅲ段选用喷锚支护。竣工后期的变形监测数据表明该支护方案的选择是成功的。     

非饱和膨胀土水分迁移的试验研究

在等温条件下,分组对不同初始干-湿段土体含水量、不同时间间隔对非饱和膨胀土的气态水迁移和气液态水混合迁移的规律及其关系进行试验研究,揭示了其随时间的变化过程。试验结果表明,土质情况、含水量水平及含水量梯度对其有重要影响,气态水迁移量与气液混合迁移量都随含水量梯度增加而增加,与时间和位置呈复杂的非线性关系;含水量较小时,土粒对水分的吸附能力较强,致使含水量梯度较大,含水量较大时,土粒周围自由水较多,水分分布较均匀。     

VRPSTW的混合改进蚁群优化算法*

软时间窗车辆路径问题（VRPSTW）是VRP的一种重要扩展类型,定义了其惩罚函数并建立数学模型。设计用于求解该问题的混合改进型蚁群算法并求解标准数据库中的紧时间窗实例。经过大量数据测试,获得了较好的效果,并验证了蚁群算法用于求解软时间窗车辆路径问题的成功实现。