Yard Trimmings as a Source of Nitrogen for Crop Production

Yard trimmings from sources rich in grass clippings have the potential to supply nutrients for crop production. Our objectives were to estimate N availability from yard trimmings and determine their effects on crop production, soil nutrients, and organic matter levels. We conducted a field experiment, comparing three consecutive years of yard trimmings applications (22, 44, or 66 Mg ha^?1 yr^?1 dry weight) with inorganic N (112 kg N ha^?1 yr^?1) and zero-N controls in a silage corn (Zea mays L.) - winter triticale (Triticosecale spp.) rotation. The yard trimmings were screened and ground, and allowed to heat for a short period. They were incorporated each spring before planting corn. We measured crop yield and N uptake, and estimated apparent N recovery (ANR). We measured soil inorganic N two weeks after yard trimmings application and after corn harvest. In a one-year on-farm demonstration, we compared three sources of yard trimmings applied at a single rate. Yard trimmings applied at 44 Mg ha^?1 dry weight provided sufficient available N to replace inorganic N. For silage corn grown with summer irrigation, estimated ANR in the crop was 7% in Year 1, 19% in Year 2, and 18% in Year 3 at the 44 Mg ha^?1 yard trimmings rate, compared with a mean ANR of 65% for the inorganic N treatment. Postharvest soil nitrate residual (0-to 120-cm depth) was similar for the 44 Mg ha^?1 treatment and inorganic N treatment. We observed variation in N availability with year and source of material. Yard trimmings also increased soil test K and organic matter.     

Microbial Population Dynamics and Enzyme Activities During Composting

The changes in population size of different microbial groups (total aerobic heterotrophs, actinomycetes, fungi, fecal coliforms, ammonium- and nitrite-oxidizing bacteria, and denitrifying bacteria) and the activities of 19 different enzymes (three phosphatases, three esterases, two proteases, three amino-peptidases, and eight glycosyl-hydrolases) were examined during cocomposting of poultry litter (a mixture of poultry manure, waste feed, feathers, and wood shavings) and yard trimmings (a mixture of grass clippings, leaves, and wood barks). Three piles with forced aeration were established by mixing 2:1 (v/v) ratio of poultry litter and yard trimmings. During composting, samples were taken at three different locations (top, middle, and bottom) of the forced aeration piles for microbial and enzyme analyses. Results demonstrated that population size of different microbial groups was not a limiting factor in this composting process as the microorganisms in the poultry litter + yard trimmings compost are in great abundance. Although the numbers of these microbial groups were reduced by high temperature, their populations multiplied rapidly as composting progressed. Fecal coliforms were eliminated by day 49, suggesting that the poultry litter + yard trimmings compost showed an overall increase in diversity and relative abundance of extracellular enzymes present as composting progressed. The population of fungi and actinomycetes (microorganisms active in degradation of cellulose, hemicellulose, and lignin) were positively correlated with esterase, valine amino-peptidase, α-galactosidase, β-glucosidase, and lipase. Of all 19 enzymes examined, ß-galactosidase (enzyme involved in the hydrolysis of lactose) had the most significant positive correlation with microbial populations, such as total aerobic heterotrophs, ammonium- and nitrite-oxidizing bacteria, denitrifying bacteria, and fecal coliforms. Cystine amino peptidase, chymotrypsin, and trypsin showed no evidence of activity during the entire period of composting. This composting process represented a combined activity of a wide succession of environments in the compost pile as one microbial group/enzyme overlapped the other and each emerged gradually as a result of the continual change in temperature as well as moisture content, O₂ and CO₂ level, and progressive breakdown of complex compounds to simpler ones.     

相变混凝土能量桩热-力学特性的数值模拟与试验验证

为了获得热力耦合作用下相变混凝土能量桩的热-力学特性,建立了其三维数值模型,比较了传统和相变混凝土能量桩热-力学特性的差异,分析了埋管管腿间距及桩体长径比对相变混凝土能量桩热-力学特性的影响规律。结果表明,相变材料（Phase Change Material,PCM）的固液相变可使单位桩深换热量提高10.3%,且可降低桩身温度变化幅度,由温度变化所引起的桩身位移、轴力及侧摩阻力变化量也相应减小。随桩基埋管管腿间距增加,能量桩的换热量和土壤热影响范围增大,桩身轴力减小,桩身位移呈现先增大后减小趋势;加大桩体长径比会增加总换热量,但会导致单位桩深换热量降低及桩顶位移的增加,不利于桩基结构的稳定性。试验验证表明：所建能量桩数值模型可用于模拟相变混凝土能量桩的热-力学特性,其桩壁中点温度与桩顶位移的预测最大相对误差分别在5.1%与12%以内,平均相对误差分别为4.2%、9.9%。研究结论对于相变混凝土能量桩的优化设计与运行具有重要指导意义。     

Effects of Turning Frequency,Leaves to Grass Mix Ratio and Windrow vs. Pile Configuration on the Composting of Yard Trimmings

Because of proposed bans on the landfilling and incineration of leaves, grass and brush, large-scale composting is fast becoming the primary disposal option for yard trimmings in many states. Few systematic studies have been done to compare the effects of turning regime, feedstock mix ratio, or windrow vs. pile configuration on composting and the characteristics of finished compost. In this study, various ratios of leaves, grass and brush were mixed and composted in two series of windrows; and one set of static piles. One windrow series (#1) was turned seven times every four weeks, while the other windrow series (#2), and the piles, were turned once every four weeks. The effects of the different treatments were examined by measuring compost temperature, oxygen concentration, pH, organic matter and moisture content, volatile fatty acid content, bulk density, stability, humification and seed germination indices, total and available nutrient levels, and particle size distribution. Results showed that turning frequency had little impact on oxygen concentrations, VFA content and temperatures during the composting of yard trimmings in windrows, however, in piles temperatures were substantially higher and oxygen concentrations fluctuated greatly. The composts from all the treatments were stable, (oxygen uptake rates < 0.1 mg O₂/g OM/hr) after 60 days of composting regardless of the turning frequency, mix ratio or configuration. The bulk density inereased much more rapidly in frequently turned windrows than in the other treatments and particle sizes were smaller in these windrows. In most respects however, the final composts (day 136) were remarkably similar and none inhibited Cress seed germination or root elongation. The pH of all the composts, and the soluble salts and nitrate levels in composts made with high levels of grass, exceeded guidelines for greenhouse growth media.     

桩基螺旋型地埋管换热器换热性能的数值模拟与验证

为了探讨不同因素对桩基螺旋型地埋管换热性能的影响,建立了桩基螺旋型地埋管换热器的传热数学模型,分析了桩基直径、桩基深度、螺旋管组数、土壤类型对桩基螺旋型地埋管换热量及土壤温度分布的影响,结果表明:增加桩基直径有利于改善桩基的蓄热能力、提高螺旋型埋管的换热性能,但是单位管长换热量会减小,因此,桩基直径不可无限制增加;桩基深度的增加有利于提高桩基螺旋型埋管换热器的换热量,而且对单位长度桩基的换热量影响很小,因此,可以通过增加桩基深度来提高换热量;同样条件下,黏土、砂土、砂岩中砂岩最有利于桩基换热器换热,土壤温度上升速率和幅度最低,而黏土换热效果最差,土壤温度上升速率最快;此外,螺旋管组数越多,换热器换热量越大,但是单位管长换热量会大幅下降。试验验证表明:所建桩基螺旋埋管模型预测出的换热量与土壤温度值与对应试验值吻合较好,其最大相对误差分别在9.7%与9.2%以内。     

温度对煤矸石山水分及植物生长的影响——以山西省阳泉市煤矸石山为例

 采用野外调查试验、取样和室内分析的方法,研究煤矸石山温度对水分及植被生长的影响。结果表明:煤矸石山温度在垂直方向随着深度的增加有上升趋势,与自然黄土荒坡变化趋势相反,且覆土后的煤矸石山较自然恢复煤矸石山温度变化剧烈;在垂直0～80cm的范围内,自然恢复、覆土50 cm和覆土100cm煤矸石山相邻土层（10cm）温度升高值分别为0.68、2.20和2.97℃;覆土煤矸石山水分含量在垂直方向因温度升高逐步下降,其水分含量较自然恢复煤矸石山平均高出10%～15%;在山西省阳泉市煤矸石山适宜生长的耐高温植物有灰绿藜、茵陈蒿、蒺藜、马齿苋、臭蒿、狗尾草、沙打旺和鬼针草,4种植物对温度敏感程度由高到低依次为紫穗槐>刺槐>臭椿>侧柏。     

稻壳与煤混合燃烧特性试验

采用非等温热重法对稻壳、煤及其混合燃料进行燃烧试验,使用Flynn-Wall-Ozawa（FWO）和Kissinger- Akahira-Sunose（KAS）2种方法分析了样品的燃烧反应动力学参数,分析了掺混比、升温速率对燃烧特性参数的影响,探讨了燃烧过程中混合燃料成分间的协同效应。结果表明：混合燃料的点火温度与纯煤相比有明显降低,燃烧特性有明显改善,随着稻壳掺混比由10%升至70%,燃尽温度从730℃降低至650℃,燃尽程度也逐渐变大,失质量从86.1%增至91.5%,综合燃烧特性指数从2.153×10-8增加到1.183×10-7;随着升温速率的增加,混合燃料的燃尽温度和综合燃烧指数均会增大,但点火温度和燃尽程度几乎不变;稻壳与煤混合燃烧时组分间会发生协同作用,且随着稻壳掺混比的增加,协同效应参数逐渐增大,协同效应越来越明显;FWO和KAS法得到的煤的活化能分别为37.66和31.00 kJ/mol,稻壳的活化能分别为20.96和16.30 kJ/mol;混合燃烧过程中,活化能随着温度和转化比而改变,随着稻壳掺混比的增加呈现出先增大后减小的趋势。     

大型煤矸石山植被重建的土壤限制性因子分析

煤矸石是我国第一大固体废弃物,巨量煤矸石堆积压占了大量土地,并影响矿区及周边水土环境,煤矸石山的植被重建是解决上述问题的经济而有效的途径。国内外研究与实践表明,表层土壤特性是矸石山植被重建成功与否的决定性因素。由于表层物料组成以及所处地域等因素,目前对煤矸石山各限制性因子及其重要性看法有所不同,从而影响了措施设计及植被效果。本文以抚顺西露天煤矿等煤矸山为例,对大型煤矸石山植被恢复的诸多限制性因素进行了分析论述,认为表层风化物的主要限制性因子依次为质地、水分、养分、pH、盐分、表层温度、重金属等,这与以往研究有所不同,体现了该煤矸石山的区域特色。研究结果可为制定适宜的煤矸石山及其类似废弃物堆场的植被恢复措施提供依据。     

植被自然恢复对煤矸石堆场Fe/Mn淋溶迁移的影响及其作用效果

[目的] 探讨植被自然恢复下植被类型对煤矸石堆场Fe,Mn淋溶迁移的影响及其作用效果,为煤矿区煤矸石堆场的生态环境治理及生态修复提供科学依据。[方法] 通过对贵州省中部废弃煤矿区不同植被条件下煤矸石堆场地表径流进行采样分析,同时通过移植煤矸石堆场上生长的马尾松、光皮桦和类芦进行盆栽试验以及采集基质渗透水样品。[结果] 马尾松、光皮桦及类芦生长的煤矸石基质渗透水和煤矸石堆场地表径流水中Fe,Mn含量均显著地低于无植物生长的煤矸石,煤矸石堆场植被自然恢复后地表径流水中Fe,Mn含量下降率分别达45.27%~85.60%,60.17%~90.13%,植被作用效果的大小顺序为：马尾松幼林 > 阔叶树幼林 > 类芦草丛。同时,马尾松幼林、阔叶树幼林、类芦草丛煤矸石堆场地表径流水中泥沙含量分别比无植被裸露的煤矸石堆场平均减少了40.18%,30.67%,27.91%。煤矸石中矿物颗粒态Fe,Mn的迁移量也出现明显的降低。[结论] 植被自然恢复能显著地减少煤矸石堆场Fe,Mn向水体的迁移及改善废弃煤矿区地表水环境质量。植物生长,特别是马尾松生长对减少煤矸石中Fe向水体迁移产生的环境效应大于Mn。     

进气成分对柴油机燃烧特性的影响

为了研究进气成分对柴油机着火和燃烧过程的影响,在一台视窗上置式柴油机可视化实验装置上,用高速摄像机记录了油门全开时不同进气成分下柴油机燃烧过程的火焰照片,应用三基色法计算了燃烧温度场,结合示功图和放热率曲线分析了不同进气成分对柴油机燃烧特性的影响。结果表明:当进气成分不同时,缸内着火时刻、燃烧持续期、最大爆发压力和最大放热率均发生相应改变;同时,进气成分的改变对缸内最高温度和平均温度的影响较大;另外,进气同时加入2%H2和10%CO2可以在氧体积分数减少的情况下改善燃烧,有利于降低柴油机有害排放物的生成。研究结果为实现柴油机高效、低污染燃烧提供一种新的方法。     

Amended and composted log yard fines as a growth medium for crimson clover and red top grass

Abstract

Log yard residues (LYR) a bark and soil waste material produced during log handling, could find use as a growth medium for plants. In this study, log yard fines (LYF), a screened fraction of the LYR (<1.3 cm), were either not amended or amended with a N‐S fertilizer mixture (LYF + F) or with cow manure (LYF + M) and then composted outdoors in insulated, aerated tanks for 18–22 weeks. The resulting substrates were then evaluated as growth media for ‘Chief crimson clover (Trifolium incarnatum L.) and ‘Streaker’ red top (Agrostis alba L.). Plants were fertilized (0 or 78 kg N/ha) and grown in a growth chamber.

Temperatures in the LYF and LYF + F piles were similar to ambient conditions over the 5–6 month treatment period, whereas the manure‐amended pile reached a maximum of 34°C after two weeks and then cooled to ambient after two additional weeks. The final C/N ratio of the nonamended LYF was 85 as compared to 36 for LYF + M and 44 for LYF + F. Clover and red top grew best (height and biomass) in LYF + F and poorest in LYF + M, regardless of fertilization regime. Red top grew poorly in the nonamended, unfertilized LYF presumably due to the high C/N ratio of this medium. In summary, this study suggested that LYF could be either amended with fertilizer and aged in piles or directly land applied with supplemental fertilization to support plant growth.     

Particle Segregation Within a Pile of Bulk Distillers Dried Grains with Solubles (DDGS) and Variability of Nutrient Content

Piling Dried Distillers's Grains with Solubles (DDGS) using gravity discharge is common in the corn‐ethanol industry. This study investigated the occurrence of particle segregation within piles of DDGS formed by gravity discharge and subsequent spatial nutrient variability. Particle segregation tests were performed in a laboratory study where piles of DDGS were formed using samples collected from two fuel ethanol plants (an “old” and a “new” generation plant), and a plant study performed on piles of DDGS formed at the same two fuel ethanol plants. In both the laboratory and plant studies, the piles were formed by gravity‐driven discharge and sampled at various categorized sections from the center of the pile to the periphery. Our results gave similar conclusions to a prior bench‐scale study and confirmed that particle segregation does result in significant differences in particle size at the sampled locations of the pile. Particle size expressed as the geometric mean diameter (d_gw) increased from the core of the pile to the periphery. Of all the nutrient composition tested, only crude protein and moisture correlated with particle size. While the correlation of crude protein with particle size was not consistent and clearly discernible in all the piles sampled in both the bench‐scale and plant studies, the correlation of particle size with moisture showed a strong positive correlation. Based on these findings, we recommend the development of a standard sampling protocol following good sampling practices for bulk granular solids.     

基于热平衡及热湿参数动态分析红梅杏防霜棚“冷室效应”

针对宁南地区红梅杏防霜棚夜间棚内环境温度长期低于棚外，即出现了“冷室效应”，未达到预防霜冻效果，依据质、热平衡原理分别研究防霜棚覆盖层、棚内湿空气和土壤层的热量收支情况，以及防霜棚系统在棚布覆盖-次日收拢时段棚内热量蓄积情况；分析棚内主要热湿参数的动态过程，以此探究防霜棚内相对湿度及湿空气状态变化对相变潜热的影响和棚内“冷室效应”的产生机理，为改进设计提供理论依据，以达到有效预防霜冻灾害的目的。结果表明：（1）春、秋季夜间棚内出现“冷室效应”时土壤层和覆盖层均因热损失较高成为失热部分，而棚内湿空气因得到热量较多成为得热部分。（2）春、秋季棚布覆盖-次日收拢时段棚内累计得热量低于累计失热量，导致棚内热量失衡。（3）棚内湿空气热湿参数与棚外热湿参数存在显著差异（春季棚内的饱和水汽压除外）；夜间棚内水汽密度与露点温度的动态变化过程均可反映因蒸发及冷凝而产生的潜热变化规律；棚内低温和较高的水汽密度使饱和水汽压与实际水汽压无限接近，导致棚内相对湿度持续偏高。红梅杏防霜棚夜间累计得热量始终小于累计失热量，土壤层和覆盖层为最主要的热损失部分，在热量失衡的情况下出现了“冷室效应”。     

Winter Composting Using the Passively Aerated Windrow System

Field trials demonstrated that agricultural wastes could be successfully composted in the winter with the passively aerated windrow system. Three small windrows were constructed. One pile contained a sheep manure-straw mixture, while the other two piles contained varied amounts of horse manure, cow manure, and bedding materials (straw, wood chips). The piles were constructed on a porous base of wood chips. Standard four-inch (10 cm) perforated pipes were placed approximately three feet apart in the porous base, perpendicular to the length of the windrow. Piles were covered with 15 to 20 centimeters of finished compost. A commercial compost covering fabric permeable to gases and water vapor but impermeable to liquid water was used for additional insulation and protection against high winds. Ambient temperatures ranged from ?27°C to 15°C during the trials. Initially, all three piles froze. Then the ends of the piles began to heat up, with the southern ends which received the most sunlight heating up first. Plugging the pipes seemed to help the piles heat up faster, but did not appear to be necessary. Thermophilic temperatures were attained and the composting cycle took 50 to 80 days after the piles heated up. Oxygen levels were highest at the bottom of the pile, and decreased as one moved to the top of the pile. The biggest practical problem encountered was the snow drifts that periodically formed at the windrow base, covering the pipe openings.     

EGR对轻型柴油机缸内燃烧及排放性能影响的可视化

为探索EGR对轻型柴油机小负荷工况下缸内燃烧及排放性能的影响规律,该文以某高压共轨轻型柴油机为样机,搭建柴油机缸内工作过程可视化研究平台,通过缸内燃烧过程高速摄影、缸内示功图采集及放热率计算分析了EGR对轻型车用柴油机燃烧过程及排放性能的影响规律。研究表明:通过所搭建的柴油机缸内工作工程可视化平台可以直观的分析柴油机缸内喷雾燃烧过程。小负荷工况条件下,随着EGR率的增加,滞燃期缩短,柴油机缸内燃烧持续期延长,燃烧后期平均温度上升,缸内压力峰值、瞬时放热率峰值均降低,与EGR率为10%时相比,EGR率40%时NOX、HC和CO排放分别下降了65.6%,46.4%和8.7%,而炭烟的排放先减小后增大,EGR率超过30%后炭烟排放及燃油经济性出现恶化。该研究可为有效降低柴油机排放提供参考。     

Quantifying the Amount of Yard Trimmings to Be Composted in the United States in 1996

? Based on estimates by the Environmental Protection Agency of the amount of yard trimmings to be generated in coming years, the author calculates that up to 17.1 million tons will be composted in 1996 — the year by which existing state bans on landfill disposal of yard trimmings will all be in effect. Assuming a 50 percent weight reduction through the composting process, up to 8.5 million tons of end product will be generated in 1996. While the estimates provided in this paper are based on assumptions that could be changed by many factors, the calculations do provide springboards for asking questions regarding the composting infrastructure in terms of whas is expected to be in place in terms of educational needs, collection needs, production facilities and effective markets.     

玉米秸秆与油页岩混烧的热重试验

为了充分燃烧利用农业生物质与油页岩,采用热重-差示扫描量热(TG-DSC,thermogravimetric-differential scanning calorimetry)技术对玉米秸秆与油页岩混合燃料进行了热重试验,对其各燃烧特性与燃烧机理进行了分析并计算了燃烧动力学参数。结果表明,混烧试样的微分热重(DTG,differential thermogravimetric)曲线出现4个峰值,主要分别是半纤维素热解、纤维素热解、木质素和油页岩热解,以及油页岩焦炭燃烧和油页岩无机盐热解。在DTG曲线第1至第3峰之间出现DSC曲线放热峰,在DTG曲线第3峰至第4峰之间出现DSC曲线吸热峰,需要强化混合燃料的前期燃烧;玉米秸秆与油页岩的质量比例为4∶1时的混合燃料S2,其混烧的可燃特性、着火特性及综合燃烧特性指数均最大,燃尽时间最短,燃尽特性指数较大;在前3个温度区段,混合试样的活化能及频率因子均随温度区段的升高而降低,体现了活化能与频率因子变化的一致性;低温阶段与高温阶段反应级数分别约为1.5及0.7。研究结果可为生物质和油页岩的混烧利用提供参考。     

Subsurface leachate migration from a reject coal pile in South Carolina

Transport of contaminants from coal storage areas through the rooting zone has the potential to negatively affect shallow ground water and terrestrial vegetation. Reject coal piles represent a worst-case scenario for contamination from coal storage areas because of the long residence time of the coal. Preliminary hydrologic data were collected from an area of stressed vegetation adjacent to an inactive ash basin and reject coal pile in South Carolina. The water table is near the surface (< 60 cm) in this wetland area and water movement is primarily to the west, toward the Savannah River. Acid leachate migration from the reject coal pile has contaminated the water-table aquifer with sulfate (up to 22 200 mg L^?1) and metals (Fe to 9560 mg L^?1) Al to 1110 mg L^?1) A shallow plume of contaminated ground water parallels the reject coal pile and is elongated in the direction of ground-water movement. The plume is migrating westward at a calculated velocity range of 6.3 to 10.4 m yr^?1. Leachate migration from the reject coal has produced a highly acidic (pH down to 2.2) and highly saline (EC to 11.8 dS m^?1) rooting zone and is most likely responsible for the stressed vegetation in the study area.     

农业生物质燃烧特性及燃烧动力学

为了充分燃烧利用农业生物质,采用 TG-DTG-DSC ( thermogravimetric-differential thermogravimetric-differential scanning calorimetry)联用技术对玉米杆、玉米芯、稻草、龙眼枝、荔枝条及其混合燃料进行了热重试验,考察了其可燃特性、着火特性、燃尽特性及综合燃烧特性,计算了燃烧动力学参数.结果表明,玉米杆及玉米芯燃烧前期DTG曲线分别出现2、3个峰值,而稻草、龙眼枝及荔枝条燃烧前期DTG曲线均只出现一个峰值;玉米杆及稻草燃烧中后期出现DSC曲线的吸热峰;玉米杆的可燃特性指数及着火特性指数均最大,且着火温度最低,荔枝条的燃尽特性指数最大,玉米芯的综合燃烧特性最好;低温阶段反应级数约为1.0~1.2,高温阶段反应级数约为0.5~0.8,低温阶段活化能大于高温阶段的活化能;生物质燃烧前期属于均相着火,后期属于多相着火.秸秆类生物质纯烧的后期稳定性较差,在木质类生物质中适当加入秸秆类生物质有利于混合燃料的前期燃烧,研究结果可为农业生物质的燃烧利用提供指导.     

内衬塑料地下粮食筒仓粮堆温度场研究

为了研究地下仓储粮期间粮堆的温度变化,该研究以湿基含水率为23%的高水分玉米为研究对象,首先采用试验方法对内径3 m,高5 m的地下筒仓在静态储藏条件下的仓内温度场的变化进行了分析。然后基于多孔介质传热理论,使用多物理场数值模拟软件COMSOL对试验仓进行了模拟研究。数值模拟基于实际堆粮高度,充分考虑了仓内谷物颗粒呼吸作用对粮堆内温度场分布的影响,研究了不同初始粮温、粮食种类和装粮季节对仓内温度场的影响。结果表明：静态储藏阶段,粮食的呼吸作用较强,粮堆首先在底部开始升温,并逐渐形成高温热芯,随后热芯位置逐渐向粮堆中上部移动,并最终稳定于距装粮线1 m处。初始粮温为35 ℃时,仓内粮堆温升最高,为6.1 ℃,温度达到峰值后出现下降趋势;在5种不同种类（玉米、油菜籽、大豆、小麦和稻谷）粮堆中,油菜籽堆平均温升最高,为1.6 ℃,玉米堆平均温升最低,为1.2 ℃;不同季节外部环境温度的变化对仓内粮堆温度变化影响很小,仓内粮堆温度在不同季节条件下表现出一致的变化趋势。该研究对地下仓高水分粮储藏期间的温度变化进行了研究,并拓展了数值模拟,可为实际工程提供参考。