Spatial Distributions of Atmospheric Radiative Fluxes and Heating Rates over China during Summer

The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.

Study of the Photon Flux and the Dose Rate in the Vicinity of a 60Co Gamma Irradiator

The present work presents an overview of the study of some dosimetric quantities in the vicinity of the Tunisian Gamma Irradiation Facility. Firstly, we have confirmed our previous calculation of the photon flux and the dose rates, using a simulation with GEANT 4. A good agreement between calculation and simulation was obtained, which well confirmed the modeling of the CNSTN extended source by a pencil-like source. Secondly we have determined the isodose curves in the vicinity of the irradiator using a straightforward calculation. Finally, we have presented many comments for some published work concerning the methods used to determine these dosimetric quantities.

Effect of Carbon Properties on Melting Behavior of Mold Fluxes for Continuous Casting of Steels

During continuous casting of steel, the properties of mold fluxes strongly affect the casting performance, steel quality and environment of casting operation. The high temperature microscopy technique was used to investigate the melting behaviour of mold fluxes, and drip test method was used to determine their melting rate. The results showed that free carbon is a dominant factor in governing the melting behaviour of fluxes, and the melting rate is increased with increasing carbon reactivity and decreasing carbon content.

STUDY ON THE DISSOLVED OXYGEN FLUX IN THE SOUTH CHINA SEA

The seawater box model for the South China Sea (SCS) was used to calculate the fluxes of dissolved oxygen in Box I, Box Ⅱand Box Ⅲ for establishing the box model of dissolved oxygen (DO)in the SCS.The total input flux of oxygen to the SCS was calculated to be 280.4×104 mol/s, of which 49.2% was transported into the sea by outer oceans, 30.3% came from organisms photosynthesis, 3% from rainfall, 0.4% from rirers, and 17.0% from the atmosphere.

Surface Roughness of Flux Film in Continuous Casting Mold

The corundum plates with a groove were used to freeze molten flux into solid slice to simulate the flux film formed in continuous casting mold,and thereby to study the formation mechanism of flux film with different surface roughness.The effect of some factors on the surface roughness of flux film,such as reheating rate,cooling rate,flux film thickness and crystallization ratio,was discussed.

Parameterization of Sheared Entrainment in a Well-developed CBL.PartⅡ:A Simple Model for Predicting the Growth Rate of the CBL

Following the parameterization of sheared entrainment obtained in the companion paper, Liu et al. （2016）, the present study aims to further investigate the characteristics of entrainment, and develop a simple model for predicting the growth rate of a well-developed and sheared CBL. The relative stratification, defined as the ratio of the stratification in the free atmosphere to that in the entrainment zone, is found to be a function of entrainment flux ratio （Ae）. This leads to a simple expression of the entrainment rate, in which Ae needs to be parameterized. According to the results in Liu et al. （2016）, Ae can be simply expressed as the ratio of the convective velocity scale in the sheared CBL to that in the shear-free CBL. The parameterization of the convective velocity scale in the sheared CBL is obtained by analytically solving the bulk model with several assumptions and approximations. Results indicate that the entrainment process is influenced by the dynamic effect, the interaction between mean shear and environmental stratification, and one other term that includes the Coriolis effect. These three parameterizations constitute a simple model for predicting the growth rate of a well-developed and sheared CBL. This model is validated by outputs of LESs, and the results show that it performs satisfactorily. Compared with bulk models, this model does not need to solve a set of equations for the CBL. It is more convenient to apply in numerical models.

Determination of Particulate Matter Emissions from Cattle Feedlots Using Wind-Trax and the Flux-Gradient Technique

Large commercial cattle feedlots are significant sources of particulate matter (PM) emissions. This research compared WindTrax and the flux-gradient technique in estimating emissions of PM with aerodynamic diameter < 10 μm (PM10) from cattle feedlots. Meteorological conditions were measured and PM10 concentrations were profiled vertically (i.e., 2.0 to 7.62 m) at a large commercial beef cattle feedlot in Kansas from May through September 2011. Results show that between the two methods evaluated, WindTrax was least sensitive to changes in heights and number of heights used in the emission estimation, with calculated PM10 emission rates varying by up to 18% only. On the other hand, PM10 emission rates produced by the flux-gradient technique varied by almost 56% when changing either heights and/or number of heights in emission calculation. Both methods were sensitive to height settings, with their respective PM10 emission rates higher when the lowest height setting (2.0 m) was included. Calculating PM10 emission rates with the 7.62-m height led to lower estimates for the flux-gradient technique but no significant change in estimates was observed for WindTrax. As demonstrated in this study, for the flux-gradient technique, settings for the lowest and highest heights were the most critical in emission estimation;exclusion of other heights in between showed only to 2% to 6% change in calculated PM10 emission rates. In general, the higher PM10 emission rates were obtained with the flux-gradient technique. However, eliminating the lowest height (2.0 m) in the calculation and, at the same time, using a specific set of formulations for the flux-gradient technique made its calculated PM10 emission rates slightly lower (but not significantly different) than those from WindTrax.

Determination of Neutron Fluxes and Spectrum Shaping Factors in Irradiation Sites of Ghana’S Miniature Neutron Source Reactor (mnsr) by Activation Method After Compensation of Loss of Excess Reactivty

Accurate neutron flux values in irradiation channels of research reactors are very essential to their usage. The total neutron flux of the Ghana Research Reactor-1(GHARR-1) was measured after a beryllium reflector was added to its shim to compensate for excess reactivity loss. The thermal, epithermal and fast neutron fluxes were determined by the method of foil activation. The experimental samples with and without a cadmium cover of 1-mm thickness were irradiated in the isotropic neutron field of the irradiation sites of Ghana Research Reactor-1 facility. The induced activities in the sample were measured by gamma ray spectrometry with a high purity germanium detector. The necessary correction for gamma attenuation, thermal neutrons and resonance neutron self-shielding effects were taken into account during the experimental analysis. By defining cadmium cutoff energy of 0.55eV, Al-0.1% Au wires of negligible thickness were irradiated at 3kW to determine the neutron fluxes of two irradiation channels, outer channel 7 and inner channel 2 whose Neutron Shaping Factor (α) were found to be (0.037 ± 0.001) and (–0.961 ± 0.034). The neutron flux ratios at the inner irradiation site 2 were found to be, (25.308 ± 3.201) for thermal to epithermal neutrons flux, (0.179 ± 0.021) for epithermal to fast neutrons flux and (4.528 ± 0.524) for thermal to fast neutrons flux, in the outer irradiation site 7, the neutron flux ratios were found to be, (40.865 ± 3.622) for thermal to epithermal neutrons flux, (0.286 ± 0.025) for epithermal to fast neutrons flux and (11.680 ± 1.030) for thermal to fast neutrons flux.

Shortwave Cloud and Aerosol Radiative Forcings and Their Effects on the Vertical Local Heating/Cooling Rates

An analysis of atmospheric SW-radiative forcing and local heating/cooling rate is made using a one year temporal and vertical profiles of aerosol and cloud over Yaoundé (11.51°E, 3.83°N). It appears that the direct influence of aerosols on the surface compared to the TOA can be 3 times larger. Annual mean value obtained at 559 mb altitude is +27.74 W/m2 with range from 0 to +43 W/m2. At 904 mb, we obtained an annual mean of ﹣46.22 W/m2 with range from ﹣65 to ﹣9 W/m2. Frequency distribution indicates that more than 95% of ARF are between +10 and +70 W/m2 at 559 mb (upper limit of UL), and more than 85% of ARF are between ﹣70 and ﹣10 W/m2 at 904 mb (upper limit of PBL). This sign change is explained by the fact that the backscattering peaks at the upper limit of the aerosol PBL layer. The maximum CRF is noted at TOA where it reaches ﹣600 W/m2 based on the time interval and the structure of clouds. The highest values occur between 11.50 and 13.50 LST. Clouds lead to a general heating of the entire atmospheric column with a much greater effect near the surface. Aerosols effect on the heating rate profile show strong cooling during the day for the lower atmosphere, with slight heating at the upper atmosphere. This cooling contribution generally increases from the surface and peacks at the upper boundary of aerosol layer where reflectivity is the most important. Depending on the moment of the day, average heating effect of clouds peacks at surface or within the middle troposphere due to the absorption by clouds particles. Vertical profiles deeply evolve exhibiting differences that exceed ﹣3 K/day according to altitude from one hour to another during a given mean solar day.

光解速率测量技术研究进展

光解反应作为大气中链式反应的引发反应,是产生二次污染物的重要原因,光解速率作为描述光解反应强度的关键参数,其数值的准确测量愈加重要。光解速率的测量技术自被研发起不断发展,截至目前常见的测量技术有化学光度计测量技术、滤波辐射计测量技术,以及光谱辐射计测量技术等。其中:化学光度计测量技术是最直接测量光解速率的方法,不过由于其操作流程烦琐、仪器复杂,多用于实验室测量;滤波辐射计测量技术是一种简化的测量技术,具有较宽的光谱覆盖,并且仪器体积小、重量轻,缺点是测量气体种类有限,测量误差较大,多用于机载测量;光谱辐射计测量技术是最通用的测量方法,能够同时测量多种气体的光解速率,并且目前已利用该原理生产出商业化的光解光谱仪,然而光谱辐射计测量技术对光谱仪要求较高,多用于外场实验。除此之外,还可以用经验公式法与脉冲(闪过或激光)光解法来获得特定情况下的光解速率。该文总结了光解速率测量技术在各方面的应用,并对可能的研究重点进行了展望。

锂玻璃探测器^(6)Li原子数标定

在聚变包层中子学性能的实验检验中,造氚率是重要的测量参数之一,探测器中^(6)Li原子数目作为计算造氚率的归一化因子,是决定测量结果精度的关键因素,必须进行精确标定。对^(6)Li原子数标定原理、实验配置及过程、不确定度量化方法进行具体介绍,并首次在中国绵阳研究堆(CMRR)的M5水平孔道以锗单晶单色器获得32.36 meV中子对小型锂玻璃探测器中^(6)Li原子数进行了标定,不确定度为2.62%。

长江口滨海湿地有机碳循环过程及影响因素研究进展

滨海湿地是“蓝碳生态系统”的重要组成部分。综述了长江口滨海湿地土壤有机碳时空分布及含量、碳汇速率、有机碳横向输入输出通量及量化方法、有机碳循环定量分析模型以及有机碳储量和组分对不同影响因素所做出的动态响应规律,发现在土壤有机碳水平空间分布上,崇西湿地>崇明东滩>九段沙>南汇潮滩;有机碳通量和浓度变化主要受到植物生物量和结构、水和土壤的理化性质、陆源输入和潮汐动力、间隙水交换以及人类活动和全球气候变化的影响。未来应加强长江口湿地土壤碳库和有机碳输运通量统一观测,准确量化各主要因素对有机碳的贡献,这对研究盐沼湿地的碳循环机理和碳汇评估具有重要意义。

反应堆中子注量率对数测量技术研究

反应堆核仪表系统通过一系列布置在堆外的中子探测器进行反应堆中子注量率测量,为反应堆启动、运行和安全提供初始测量信号。中间量程中子注量率测量范围超过6个量级,同时探测器输出的电流十分微弱,最小达到10 pA,对测量技术要求较高。线性电流测量方法会产生由量程切换带来的测量跳变,影响反应堆周期测量稳定性,从而影响反应堆安全。本文详细分析了对数测量原理,利用对数放大电路具有宽动态范围的特点,实现了很宽的动态范围的中子注量率快速测量,避免了量程切换带来的测量数值跳变,提高了中子注量率测量和周期计算的精度。模拟探测器信号输入10 pA~100μA的微电流进行测量,结果表明,对于范围达7个数量级的输入电流,测量的相对误差低于0.5%,该方案适用于反应堆中子注量率的中间量程测量。

大型烟气CO_(2)填料吸收塔的设计研究

本文综合考虑脱碳剂对烟气二氧化碳(CO_(2))的物理、化学吸收作用,进行了45万m^(3)/h烟气CO_(2)填料吸收塔的设计,详细计算了填料吸收塔的直径、高度、脱碳剂循环量、填料层气液间CO_(2)的传质系数、传质通量、停留时间和CO_(2)脱除率等参数。结果表明,填料吸收塔中脱碳剂对CO_(2)的脱除率可以达到98.2%,CO_(2)反应属于液膜控制,总传质系数较低,填料吸收塔的设备体积庞大,投资运行成本较高。

吐鲁番市高昌区不同固沙植物的防风固沙效益

为了解不同防风固沙林对风速、输沙通量和土壤蚀积程度的影响,以期为荒漠化地区植物选择和配置提供技术支持,以吐鲁番市高昌区恰特喀勒乡公相村为实验地,利用气象站、风速仪、集沙仪等监测不同高度下梭梭林、柽柳林以及梭梭-柽柳混交林的风速、地表粗糙度、输沙通量等指标,分析比较不同固沙林的风速廓线、风速增加率、地表蚀积量及风沙堆积物变化规律。结果表明:随着风速的增加,输沙通量逐渐增加,地表粗糙度和蚀积深度呈现降低趋势;不同固沙林不同高度(h)的风速增加率均表现为中层(50 cm<h≤100 cm)最大,低层(10 cm<h≤50 cm)最小,说明固沙植物对低层风速有显著降低作用,增强了中层风速;不同固沙林输沙通量随着高度增加逐渐减小;柽柳林、梭梭-柽柳混交林后出现堆积现象,梭梭林前后为侵蚀现象。梭梭林、柽柳林以及梭梭-柽柳混交林均降低了近地表风速,有效拦截了风沙流,改变了表层风沙堆积物物质组成,梭梭-柽柳混交林防风固沙效果较好。

反渗透膜耐甲醛性能的研究

本研究着重评估反渗透膜(RO)在极端甲醛浓度下的耐久性表现。研究将RO膜片放置在10000 ppm和30000 ppm甲醛溶液中进行为期7天的浸泡实验,监测膜片的通量和脱盐率变化。结果表明,在两种甲醛浓度条件下,苦咸水膜片的通量均出现了显著下降,而海水淡化膜通量的下降幅度相对较小。值得注意的是,尽管通量受到影响,但两种膜片的脱盐率在实验期间几乎未发生变化。这一发现指出,RO膜在面对高浓度甲醛挑战时,虽然其通量性能受损,但脱盐能力仍保持稳定。研究结果不仅为膜材料的化学稳定性研究提供了新的实验数据,也为工业应用中膜技术的优化和应用提供了重要参考。

反渗透膜专用中性清洗剂的研究

以鞍钢厂内中水回用系统污堵的反渗透膜元件为例,利用EDS辅助双膜池膜片测试装置实现反渗透膜专用清洗剂的快速筛选研究,并成功研制出一种绿色高效中性水基清洗剂。通过正交实验优化配方,探讨了其清洗效果,与膜厂家推荐的清洗剂进行比较。结果表明:自制清洗剂最佳组成(质量分数)为1.5%柠檬酸三铵、0.15%HEDP、0.15%FMEE、0.3%OP-10、0.3%FMES、0.01%HPMC,余量为水。受污染膜片30℃下浸泡8 h后,膜通量恢复率高达99%,远高于膜厂家推荐的清洗剂,应用前景广阔。

测试条件对超滤膜截留率和通量的影响

以50kD和100kD超滤膜为研究对象,牛血清白蛋白为测试的标准物质,测试不同的过滤方式、运行时间、测试压力和料液浓度对超滤膜截留率和通量的影响。结果表明:50kD超滤膜的截留率,不同测试条件对其影响小,偏离值<±10%;100kD超滤膜的截留率,不同测试条件对其影响较大,偏离值可以达到50%。50kD和100kD超滤膜的通量受测试条件影响都较大,实验表明截留物质相对分子质量与超滤膜截留相对分子质量之间的相对大小对通量有较大的影响;长时间的过滤(>20 min),超滤膜采用错流过滤的方式比死端过滤更有优势,通量衰减慢且更稳定。

PTFE中空纤维膜蒸馏高盐废水浓缩实验研究

文章选择工业生产中常见的含氯化钠(NaCl)高盐废水,以疏水性PTFE中空纤维膜组件为载体,采用真空膜蒸馏的方式进行浓缩处理实验研究,研究各操作条件对膜通量和截盐率的影响,并验证实验可行性。实验结果表明,膜下游侧压力增加,膜通量会逐渐降低;废水料液流量和料液温度的增加均有助于提高膜通量;废水料液浓度的增加,会抑制传质过程,降低膜通量。各操作条件对膜截盐率的影响很小,膜截盐率一直保持在99.8%以上,说明PTFE中空纤维膜蒸馏用于高盐废水浓缩具备可行性。

热管置入式墙体供暖季传热性能分析

墙体是建筑的主要组成部分之一,其热损失占据了冬季供暖能耗的一大部分,因此降低墙体热损失是建筑节能领域的研究重点.热管置入式墙体(wall implanted with heat pipes,WIHP)是一种新型的太阳能被动式利用技术.通过TRNSYS软件建立了一个新的WIHP传热部件,并通过实验测试进行模型验证.对WIHP不同方向的传热性能进行分析,并提出两种WIHP的优化方式.结果表明,在工作期间,南向WIHP、西向WIHP和东向WIHP均可以提高内表面温度,减少墙体热损失,节能效果显著.