共查询到20条相似文献，搜索用时 218 毫秒
1.
为了研究灰分对煤自燃能力的影响作用,利用绝热氧化实验装置对不同灰分含量煤样进行升温氧化实验,采用R70、TCPT、B 3种指标表征灰分含量对煤样自发氧化过程的影响。结果表明：1）灰分含量越大,煤样低温氧化阶段温升速率越小,温升加速点温度越高,煤样的自发氧化过程越慢,煤越不易自燃;灰分含量大于40%后,煤自燃倾向性快速减弱。温升加速点是反应微观信息的零活化能温度的宏观累计结果,具有直观且滞后的特点。灰分越大,滞后越明显,温差越大。2）R70、TCPT、B 3种指标与灰分关系表现为二次函数。R70和TCPT两种指标显示灰分越大,自燃倾向性越弱,与实践经验相符。受水分权重影响,B指标显示煤样在灰分小于40%时,灰分越大,煤样自燃倾向性越强,这与实践经验相悖。因此,B在判定灰分对煤样自燃倾向性的影响时具有一定的局限性。 相似文献
2.
着装行为通过影响室内空气参数的设定而影响建筑空调能耗。利用能耗模拟软件DeST,计算出该地区典型着装行为下实测运行参数与期望参数对应的建筑空调能耗比推荐标准下能耗分别降低了10.86%和13.16%。而基于典型着装行为的实验热学性能参数下,平均只降低4%,说明由着装热阻关联的主观温度需要按地区着装行为进行修正。提出了控制建筑空调能耗的着装行为调节模型,着装行为节能率εc为负值时节能,为正值时不节能。京津地区办公建筑节能率为0的临界服装热阻为0.563 clo,空调系统设计和运行节能的前提是,着装热阻低于临界值。着装行为调节模型为地区着装形式和着装面料提供了量化标准,为精确控制建筑能耗提供了一种方法。 相似文献
3.
研究中国南北人群在中性环境下,生理适应的自主神经调节和主观评价差异。采用实验设计,遴选16名南方大学生和16名北方大学生,测试生理参数,包括皮肤温度、心率、心率变异性（HRV）、血容量（BVP）、肌电（EMG）,填写主观问卷。实验结果发现：1）中性环境,北方人群感觉是舒适的,各项评价指标接近中性和适中,数据较集中;南方人群感觉稍热,评价数据较离散,但热舒适（TCV）（p=0.106>0.05）、可接受程度（p=0.838>0.05）等几个主观评价与北方人群相比没有显著差异,说明南方人群有较宽的热中性温度区和较好的环境忍耐力;2）南北人群在中性环境下,平均皮肤温度有显著差异（p=0.006<0.05）,且身体躯干部位的皮肤温度显著高于四肢皮肤温度（p=0.009<0.05;p=0.043<0.05;p=0<0.05;p=0<0.05;p=0.002<0.05）,四肢皮肤温度差异不显著,肌电无显著差异（p=0.961>0.05）。心率和心率变异性的LF/HF比值,均值有差异,但不显著（（p=0.265>0.05;p=0.618>0.05）,但BVP有显著差异（p=0<0.05）。 相似文献
4.
五星形桩是一种横截面异形桩,是在圆桩的基础上向内切割5个圆弧,形成截面类似五星形的异形桩。按其截面性质分为周长最大化五星形桩F1、周长面积比最大化五星形桩F2两种桩型,为掌握五星形桩的水平承载性能进行了与圆桩的对比模型试验研究。试验用土为干砂,砂雨法土样制作,模型桩为预制钢筋混凝土桩,相似比为1∶8。模型试验桩包括：五星形桩F1、五星形桩F2、与五星形桩F2截面周长相同的圆桩C1、与五星形桩F2截面面积相同的圆桩C2。由于五星形桩水平承载性能具有方向性,试验采用理论计算中水平承载力最大的方向施加水平荷载,试验结果表明：F1、C1和F2的水平极限承载力相当,但F2的截面面积最小,仅为C1的0.44倍;与C2相比,F2的水平极限承载力是其1.63倍,可见,合理截面形式的五星形桩可以提供更大的水平承载能力;五星形桩与圆桩弯矩分布规律基本一致,都在4倍直径左右（五星形桩为外接圆直径）达到最大,但五星形桩截面面积小,抗弯刚度不足,容易折断,总体水平承载性能不及截面周长相同的圆形桩,但优于截面面积相同的圆形桩。 相似文献
5.
便利店销售额在传统零售业中增幅最高,照明在所调研样本总室内能耗中占比为43%。基于全国257家便利店的数据,探讨便利店的照明特征。采用多重线性回归方法建立照明能耗预测模型,采用因子分析方法探讨客观参数与主观评价的联系。研究表明,对便利店,考虑照明节能时需同步关注其主观评价的变化;进行照明设计时需因地制宜;照明能耗预测模型为ln y=0.479 ln x1+ 0.248ln x2-0.217（y为照明功率密度,x1为单位面积照明造价,x2为典型货架位置水平照度平均值）;顾客对照明充足度的“敏感性”比照明均匀度高;提高照度平均值有助于提高主观评价。 相似文献
6.
基于CuFe2O4纳米粒子能显著增强Luminol-EDTA体系的发光,首次建立了Luminol-EDTA-CuFe2O4 NPs化学发光新体系。紫外吸收光谱和化学发光光谱表明纳米CuFe2O4注入Luminol-EDTA体系后,未生成新发光物质,结合纳米CuFe2O4的特性,提出了CuFe2O4 NPs参与Luminol-EDTA体系可能的发光机理。研究发现芦丁能抑制Luminol-EDTA-CuFe2O4 NPs体系的化学发光,结合流动注射技术,将此化学发光体系应用于芦丁片中芦丁含量的测定。在优化实验条件下,芦丁浓度在2×10-8~2×10-5 mol/L范围内芦丁浓度的对数和相对化学发光值呈线性,芦丁浓度检出限（LOD）为1.21×10-9 mol/L。将本方法应用于芦丁片中的芦丁含量测定,回收率为97%~102%,RSD为2.54%（c=1×10-7mol/L,n=11）。 相似文献
7.
为完善圆钢管混凝土轴压长柱极限承载力的计算理论,对比分析了中国国家标准GB 50936-2014和CECS 28：2012中轴压短柱极限承载力的N0计算公式,并把GB 50936-2014中基于套箍系数的N0计算公式改写成统一的形式,提出了基于正则长细比的轴压长柱的稳定系数计算式,并通过36个试件的对比,对计算式的精度和适用范围进行了分析。研究表明,现行国标GB 50936-2014中基于套箍系数的N0计算公式更为精确,基于N0计算公式和本文的稳定系数,可以计算得到更为精确的轴压长柱的极限承载力。 相似文献
8.
利用一组物料、热量守衡式及其他有关约束关系,建立了氢还原竖炉模拟模型,可定量考察消耗量、生成量和氮气、CO兑入成分、DRI金属化率、入炉煤气温度等的关系。模拟结果表明：兑入CO可使入炉煤气量从纯氢还原的1650 N·m3左右下降到1200 N·m3左右;当CO和H2的体积之比V（CO）/V（H2）约为0.6时,氮气兑入量约为0,竖炉能量利用最佳;当V（CO）/V（H2）体积比为0.3时,最佳氮气兑入成分约为11%;纯氢还原最佳氮气兑入成分约为25%;兑入氮气可以减少入炉氢气的量,但不能减少入炉气体的总量。对氢还原竖炉模拟结果可为其工艺设计、操作和节能等提供参考信息。 相似文献
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A. Maruyama W. M. W. Weerakoon Y. Wakiyama K. Ohba 《Journal of Agronomy and Crop Science》2013,199(6):416-423
Spikelet sterility in rice (Oryza sativa L.) induced by high temperatures is a major concern given global warming predictions. We studied differences among eight rice cultivars in spikelet fertility at five different temperature levels in temperature gradient chamber (TGC) experiments. Six japonica and two indica cultivars were exposed to high‐temperature gradients in TGCs during the 2005 flowering season. Spikelet sterility increased with temperature in TGCs and differed among cultivars because of both variations in temperature tolerance and timing of heading. The correlation between spikelet fertility of individual panicles and both air temperature and panicle temperature during flowering was analyzed to compare tolerances among cultivars. The temperature (T75) at which spikelet fertility was 75 % of maximum ranged from 34 to 39 °C air temperature and differed significantly among cultivars. Indica varieties had higher T75 values than japonica varieties. The T75 values based on panicle temperature also differed among cultivars, but the difference between indica and japonica varieties were less significant. We concluded that the higher temperature tolerances of indica cultivars in our experiments could be attributed to lower spikelet temperatures, and cultivars with similar spikelet temperatures still had different heat tolerances due to differences in pollination ability. 相似文献
12.
Fluorimetric Determination of the Genetic Variability Existing for Chilling Tolerance in Sweet Sorghum and Sudan Grass 总被引：1，自引：0，他引：1
M. Havaux 《Plant Breeding》1989,102(4):327-332
Chilling temperatures drastically inhibited the photochemical quenching of chlorophyll fluorescence (qQ) measured in intact leaves photosynthesizing under steady-state conditions. This effect appeared, however, to be characteristic of chilling-susceptible plant species and was not observed in plants which are known to be chilling-tolerant, indicating that the measurement of qQ can serve in practice to estimate rapidly the relative chilling tolerance of crop plants. A large number (28) of sweet sorghum (Sorghum bicolor) and Sudan grass (Sorghum sudanense) genotypes were screened for chilling tolerance using this rapid qQ method. Although sweet sorghum and sudan grass obviously behaved as chilling-sensitive plants, a considerable variation for chilling susceptibility was observed among the different genotypes tested. Some sweet sorghum varieties, such as ‘Dale’ and ‘Keller’, and most of the sudan grass varieties appeared to possess a certain degree of resistance towards low temperature stress, indicating the existence of useful germplasms in Sorghum for improving stress tolerance. 相似文献
13.
Domingo Martínez-Romero Fabián Guillén Salvador Castillo Pedro Javier Zapata María Serrano Daniel Valero 《Postharvest Biology and Technology》2009,51(2):200-205
A scrubber to remove ethylene continuously from stored environments was developed. The device comprised a cartridge heater tightly joined to the activated carbon–1% Pd. The application of heat pulses led to an increase in ethylene oxidation and to auto-regeneration of the activated carbon. The efficacy of ethylene removal was higher with the number of heat pulses. Several combinations of exogenous ethylene concentrations and heater core temperatures (100–325 °C) of the device were assayed to determine their effectiveness in removing ethylene from the storage area. The results indicated that increasing the heater temperature led to enhanced percentages of eliminated ethylene but also increased CO2 concentrations. This CO2 could come from the activated carbon due to its breakthrough. Thus, temperatures ranging between 150 and 200 °C eliminated 96–99% of ethylene, with low CO2 accumulation (0.10–0.18 kPa) and without affecting the temperature of the storage environment. Thus, this device might be a promising tool for scrubbing ethylene from storage areas for fresh horticultural produce in which ethylene can induce detrimental effects. 相似文献
14.
It is worthwhile for saving energy and protecting environment to use conductive concrete as an indoor heating engineering material. Indoor temperature is the key concern of heating system. Based on convection, radiation and Joule effect, a method to calculate temperature of concrete and indoor air was presented. The method did not need to model the air, which simplified the preprocessing. The numerical result agreed with experiment satisfactorily, with a difference of 2.40%, which proved the correctness of the model. Numerical tests of different conditions showed that electrical resistivity with higher potential than power voltage and concrete thickness was the key to increase heating efficiency. 相似文献
15.
Summary Dry seeds of rice, Oryza sativa L., containing about 13 percent moisture, were exposed to 60Co gamma raysat extremely low temperature (–196°C). M1 damage on survival rate, seedling height and seed set were found to become much smaller in the cooling treatment than in the not-cooled control. Chlorophyll and heading date mutation frequencies in the M2 generation were not affected by the decreased M1 damage caused by the cooling treatment, and the mutation frequencies could be significantly increased by applying higher doses combined with the cooling treatment. Frequency of sterile or semi-sterile mutants in the M2 generation was found to be significantly lower in the cooling treatment than in the not-cooled control.It is assumed from the experimental results that extremely low temperatures during irradiation could reduce the amount of physiological damage and gross chromosome aberrations. This results in an increased efficiency of producing minute deletions and/or point mutations. 相似文献
16.
为了探究蓄冷板对冷库融霜温度波动的影响,基于计算流体力学(Computational fluid dynam-ics,CFD)对带有蓄冷板冷库的融霜过程进行了数值模拟,并用试验验证了融霜模型的可靠性,得到了冷库在融霜过程中的温度变化云图.同时对采用两台并联冷风机连续融霜的小型冷库,在冷风机结霜时有、无蓄冷板和冷风机不结霜时有、无蓄冷板进行了试验研究,结果表明,在融霜过程中,通过对不同高度截面温度场进行温度测试发现:带蓄冷板的冷库温度均低于无蓄冷板的冷库温度;融霜风机融霜期间,制冷风机有霜时,蓄冷板使冷库温度波动下降了47.20％;制冷风机无霜时,蓄冷板使冷库温度波动下降了58.95％. 相似文献
17.
为烤烟合理施用氮肥和土壤改良提供理论和技术依据,采用田间试验研究氮肥与土壤改良剂配施对烤烟产量、产值、上等烟比例、叶片氮磷钾含量、品质指标含量和土壤氮、磷、钾含量的影响。结果表明,随着施氮量增加,不施土壤改良剂和施用土壤改良剂的烟叶产量和产值均随着施氮量的增加而增加;烟叶均价和上等烟比例呈抛物线变化趋势,分别在施氮45.0、67.5 kg/hm2时最高;相同施氮量,施用土壤改良剂的烤烟产量和产值均高于不施土壤改良剂的,但施氮量超过67.5 kg/hm2时,会降低烤烟的均价和上等烟比例。在圆顶期和成熟期,随着施氮量增加,不施土壤改良剂和施用土壤改良剂的烤烟叶片含氮量、含磷量、含钾量均呈增加趋势;相同施氮量,相比不施土壤改良剂的,增施土壤改良剂的烤烟叶片含氮量、含磷量、含钾量均明显提高,中部叶和上部叶氯离子含量降低,土壤速效氮、磷、钾含量有所提高。本试验条件下,施氮量在67.5~90.0 kg/hm2,配施土壤改良剂30.0 kg/hm2时,土壤供肥能力强,烟叶品质好,烤烟的产量和产值均较高,分别为2487~2588 kg/hm2、43538~44202元/hm2。 相似文献
18.
P. V. V. Prasad K. J. Boote J. M. G. Thomas L. H. Allen Jr D. W. Gorbet 《Journal of Agronomy and Crop Science》2006,192(3):168-177
Peanut or groundnut (Arachis hypogaea L.) sown in early spring often has poor seed germination and seedling development. The influence of soil temperature on seedling emergence and early growth of six peanut cultivars (Florida MDR98, Southern Runner, Georgia Green, SunOleic 97R, Florunner and C‐99R) was studied in natural field soil profiles in temperature‐gradient greenhouses. We evaluated the influence of a range of soil temperatures by sowing at eight dates between January 2001 and May 2002 in Gainesville, Florida. On each sowing date, two additional temperature treatments (ambient and ambient +4.5 °C air temperature) were evaluated by sowing on either end of each greenhouse and applying differential heating. In total, 16 different soil temperature treatments were evaluated. Each treatment was replicated four times in four different greenhouses. Mean soil temperature from sowing to final emergence in different treatments ranged from 15 to 32 °C. Sowing date, temperature treatment and cultivar had significant effect on seedling emergence and development (V2 stage). For all cultivars, the lowest germination was observed at the earliest sowing date (coolest soil temperature). Among cultivars, Florida MDR98 was the most sensitive to reduced (cool) temperature with the lowest germination and smallest seedling size at 21 days after sowing, followed by Southern Runner. Georgia Green was the most cold‐tolerant with the highest germination, followed by SunOleic 97R. There were no significant differences among cultivars for base temperature, which averaged 11.7 and 9.8 °C for rate of emergence and rate of development to V2 stage respectively. These results imply that cultivar choice and/or genetic improvement of peanut for cold tolerance during emergence and seedling development in regions where cooler soil temperatures persist and/or regions where early sowing is desirable. 相似文献
19.
Hossam M. Ibrahim 《Euphytica》2011,180(1):99-105
Heat tolerance in 45 chickpea, lentil, and faba bean genotypes was investigated during 2007/2008 and 2008/2009 at Alexandria
Agriculture Research Station, Alexandria, Egypt, using screening methods employing the membrane thermostability technique.
Threshold temperature to be used in screening for heat tolerance at germination was also investigated for each crop. Temperatures,
responsible for 50% germination were 40, 33.5, and 29°C for chickpea, faba bean, and lentil, respectively. Germination percent
under high temperature varied significantly (P ≤ 0.05) amongst genotypes. Germination percentage ranged from 4.8 to 71.6, 39.2 to 90.0, and 4.8 to 68.6, in chickpea, lentil,
and faba bean, respectively. Differences were significant (P ≤ 0.05) among faba bean and chickpea genotypes. Membrane relative injury (RI%) showed significant (P ≤ 0.05) variability among the genotypes and ranged from 10.57 to 58, 5.2 to 61.7, and 15.7 to 52.7 in chickpea, lentil, and
faba bean, respectively. Canopy temperature was measured to evaluate heat avoidance in tested genotypes. Infra-red thermometry
was used to measure canopy temperature and the gradient of canopy to ambient air temperature (∆TC-A) in moisture stressed and unstressed treatments. Canopy temperature, leaf water potential (LWP) and leaf water content were
affected by the level of soil moisture. Genotypes were able to bring their canopy temperatures to levels lower than ambient
air temperatures but the differences were not significant. A heat stress index (HSI) were computed relating the ∆TC-A in moisture stressed to unstressed treatments. Regression of leaf water potential (LWP) and the heat stress index (HSI) was
significant (P ≤ 0.05) in faba bean genotypes in the stressful environment. The results of the present investigation emphasize the efficiency
of membrane thermostability technique in selection for heat tolerance in early stages of growth in food legumes. 相似文献
20.
A. Yang S. S. Akhtar M. Amjad S. Iqbal S.‐E. Jacobsen 《Journal of Agronomy and Crop Science》2016,202(6):445-453
Quinoa (Chenopodium quinoa Willd.), traditionally called the mother of grains, has the potential to grow under high temperatures and drought, tolerating levels regarded as stresses in other crop species. A pot experiment was conducted in a climate chamber to investigate the potential of quinoa tolerance to increasing drought and temperature. Quinoa plants were subjected to three irrigation and two temperature regimes. At low temperature, the day/night climate chamber temperature was maintained at 18/8 °C and 25/20 °C for high temperature throughout the treatment period. The irrigation treatments were full irrigation (FI), deficit irrigation (DI) and alternate root‐zone drying (ARD). FI plants were irrigated daily to the level of the pot's water‐holding capacity. In DI and ARD, 70 % water of FI was applied either to the whole pot or to one side of the pot alternating, respectively. The results indicated that plant height and shoot dry weight significantly decreased by ARD and DI compared to FI treatment both at low and at high temperatures. However, plants in ARD treatment showed significantly higher plant height and shoot dry weight compared to DI especially at higher temperature, which is linked to increased xylem ion content. Higher quinoa plant growth in ARD was associated with increase in water‐use efficiency (WUEi) due to higher abscisic acid concentration and higher nutrient contents compared to DI. From results, it can be concluded that quinoa plant growth is favoured by high temperature (25/20 °C) and ARD is an effective irrigation strategy to increase WUE in drought prone areas. 相似文献