Adsorption mechanism of different coal ranks under variable temperature and pressure conditions

Variable temperature and pressure adsorption tests were conducted on four coal samples with different coal ranks, under simulated temperatures and pressures corresponding to coal reservoirs at different depths. The regularity of the variation in the amounts of adsorption by coals under variable temperature and pressure and 30 °C isothermal conditions are compared and the adsorption characteristics of coal under the composite effect of temperature and pressure were obtained. The adsorption test and data processing method of coal under variable temperature and pressure are presented and the effect of the mechanism of tempera-ture and pressure on the adsorption capacity of coal has been studied. The research results are of significant importance in the in-vestigation of coalbed methane storage mechanism and for the prediction of the amounts of coalbed methane at various depths.

On the Relationship between Climatic Variables and Pressure Systems over Saudi Arabia in the Winter Season

The synoptic circulation over Saudi Arabia is complicated and frequently governed by the effect of large-scale pressure systems. In this work, we used NCEP–NCAR global data to illustrate the relationship between climatic variables and the main pressure systems that affect the weather and climate of Saudi Arabia, and also to investigate the influence of these pressure systems on surface air temperature（SAT） and rainfall over the region in the winter season. It was found that there are two primary patterns of pressure that influence the weather and climate of Saudi Arabia. The first occurs in cases of a strengthening Subtropical High（Sub H）, a weakening Siberian High（Sib H）, a deepening of the Icelandic Low（Ice L）, or a weakening of the Sudanese Low（Sud L）. During this pattern, the Sub H combines with the Sib H and an obvious increase of sea level pressure（SLP） occurs over southern European, the Mediterranean, North Africa, and the Middle East. This belt of high pressure prevents interaction between midlatitude and extratropical systems, which leads to a decrease in the SAT,relative humidity（RH） and rainfall over Saudi Arabia. The second pattern occurs in association with a weakening of the Sub H, a strengthening of the Sib H, a weakening of the Ice L, or a deepening of the Sud L. The pattern arising in this case leads to an interaction between two different air masses： the first（cold moist） air mass is associated with the Mediterranean depression travelling from west to east, while the second（warm moist） air mass is associated with the northward oscillation of the Sud L and its inverted V-shape trough. The interaction between these two air masses increases the SAT, RH and the probability of rainfall over Saudi Arabia, especially over the northwest and northeast regions.

Climate Factors of Vapour Pressure and Diurnal Temperature Influenced on Radial Growth of Scots Pine in Northeastern Mongolia

To find out the optimum conditions of growth in Scots pine (Pinus sylvestris var. mongolica), we analyzed the radial growth response relationship to climate factors in boreal forests. We present growth response from 3-sites Mg (Mangui), KYH (kheyihe), NM (Nanmu) from central Daxing’an mountains. Drought observed in 1920s-1930s years. We analyzed growth response from 1920-2016. Results specified that growth of scots pine did not vary with variation in sites. We measure the influence of vapour pressure and mean maximum and mean minimum diurnal temperature have been shown by correlations of different growing seasons. Most of warm temperature during June to September and growth of Scots pine show a significantly positive increase during winter season. Overall inconsistency in climate conditions of Daxing’an mountains due to Atlantic and Pacific oceans, affects the Asian moon soon and alternatively changes the local temperature and precipitation and vapour pressure and increases the drought severity.

Forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by CNTs based on MCST with temperature-variable material properties

In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temperature-variable material propertiesis presented. Also, the boundary conditions at two ends of nano-composite rotating pressurized microbeam reinforced by CNTs are considered as simply supported. The governing equations are obtained based on the Hamilton＇s principle and then computed these equations by using Navier＇s solution. The magnetic field is inserted in the thickness direction of the nano-composite microbeam. The effects of various parameters such as angular velocity, temperature changes, and pressure between of the inside and outside, the magnetic field, material length scale parameter, and volume fraction of nanocomposite microbeam on the natural frequency and response systemare studied. The results show that with increasing volume fraction of nano-composite microbeam, thickness, material length scale parameter, and magnetic fields, the natural frequency increases. The results of this research can be used for optimization of micro-structures and manufacturing sensors, displacement fluid, and drug delivery.

水稻干燥工艺对干燥特性影响的试验研究

为研究水稻变温热风干燥特性,提高水稻干燥效率,利用自制均质干燥装置试验台对水稻进行恒温和变温的干燥试验,分析恒温、快速阶梯式升温、缓速阶梯式升温、连续式干燥和缓苏干燥对水稻干燥特性的影响。试验结果表明:采用水稻恒温干燥方式,随着干燥温度的升高,水稻干燥时间缩短;采用变温干燥方式,对水稻先升温后降温、设置缓苏阶段可以有效地缩短净干燥时间,提高干燥速率。同时,因水稻的干燥效果主要受温度和时间影响,探讨了恒温与变温干燥工艺对水稻干燥速率的影响。

Effect of Curing Regime on Degree of Al^(3+) Substituting for Si^(4+) in C-S-H Gels of Hardened Portland Cement Pastes

The effect of curing regime on degree ofAl3＋ substituting for Si^4＋ （Al/Si ratio） in C-S-H gels of hardened Portland cement pastes was investigated by 29Si magic angel spinning （MAS） nuclear magnetic resonance （NMR） with deconvolution technique. The curing regimes included the constant temperature （20, 40, 60 and 80 ℃） and variable temperature （simulated internal temperature of mass concrete with 60 ℃ peak）. The results indicate that constant temperature of 20 ℃ is beneficial to substitution ofAl3＋ for Si4＋, and AI/Si ratio changes to be steady after 180 d. The increase of Al/Si ratio at 40 ℃is less than that at 20℃ for 28 d. The other three regimes of high temperature increase Al/Si ratio only before 3 d, on the contrary to that from 3 to 28 d. However, the 20 ℃ curing stage from 28 to 180 d at variable temperature regime, is beneficial to the increase of AI/Si ratio which is still lower than that at constant temperature regime of 20 ℃ for the same age. A nonlinear relation exists between the Al/Si ratio and temperature variation or mean chain length （MCL） of C-S-H gels, furthermore, the amount ofAl3＋ which can occupy the bridging tetrahedra sites in C-S-H structure is insufficient in hardened Portland cement pastes.

变速恒频水轮机变流量工况下不稳定流动数值模拟

为了研究变流量条件下变速恒频水轮机正常运转时的涡流特性和水动力特性,基于STAR-CCM+软件进行了混流式变速恒频水轮机的水动力特性数值模拟,研究了定流量和正弦流量两种工况下导叶和转轮压力脉动特性和内部流动状态,对旋转速度改变引起的涡旋演化过程进行了可视化展示。结果表明:在低转速时,尾水管进口和转轮交界处存在随转速降低而聚合产生的大尺度涡,但在转速升高后其逐渐破碎、分离,最后消散;叶片靠近叶轮流道入口的吸力面上均存在涡流,尾水管中存在两个涡核中心,且位置随转速改变;无叶空间的压力脉动相对其余位置更剧烈,脉动幅值随着转速和流量的增大而增大。研究成果可为变速恒频水轮机的设计和工程应用提供依据和参考。

不同工况对压风机性能影响的试验研究

为有效降低压风机的能耗,提高其应用价值,采用控制变量法,研究不同入口空气参数,即入口温度、相对湿度及排气压力对压风机比能量和全效率的影响。结果表明:当相对湿度不变时,随温度的增高,比能量增大,而全效率降低;当温度不变时,随相对湿度的增大,比能量增大,而全效率降低;当排气压力增大时,比能量增大,而全效率降低,且性能斜率增大的趋势与压力呈正比关系。

多联机在超高标准接待项目中的应用

阐述了某超高标准接待项目暖通空调系统的设计特点,从分析落实业主对该项目的主要设计要求入手,介绍了室内设计参数优化、冷热源方案、系统划分、计算与验算、振动噪声控制、备用性及其他细部设计;重点介绍了三管制热回收高显热多联机+直膨式恒温恒湿新风机组+地暖方案在该项目中的应用,为超高标准接待项目及温湿度独立控制空调系统的设计提供了新的解决思路和案例。

变频调速在煤气加压站恒压供气上的应用

煤气加压站作为煤气输送的关键环节,其恒压供气系统的稳定性、高效性和可靠性对供气效果和安全运行至关重要。为了满足不断增长的用气需求,提高能源利用效率,降低供气成本,变频调速技术作为一种先进的控制手段被广泛应用于煤气加压站的恒压供气系统中。变频调速技术通过调节压缩机的转速,实现了对供气量的精确控制,可以根据实际需求动态调整压缩机的运行状态,使其始终处于最佳工作状态,从而实现了能源的有效利用和供气的稳定性。然而,尽管变频调速技术具有诸多优势,但在实际应用中仍然存在一些挑战和问题,如操作复杂性、设备稳定性、维护成本和兼容性等。因此,有必要对变频调速技术在煤气加压站恒压供气系统中的应用进行深入研究和优化,以进一步提高系统的运行效率和性能,保障供气安全和稳定,促进煤气工业的健康发展和社会经济的可持续繁荣。

闭环变风量控制系统在实验室通风系统中的应用

变风量控制系统在实验室建设中被广泛应用,有助于提升实验室的安全性和实现节能减排的目标。但由于排风柜面风速、实验室静压差、管道静压测量易受传感器安装位置、安装方式、气流扰动等因素的影响,给基于闭环控制方式的实验室变风量控制系统的设计与应用带来了挑战。文章从系统控制原理、性能影响因素出发,以变风量控制系统在某化学实验室中的应用为研究对象,采用数值模拟方法对实验室压力分布、速度分布、空气龄等核心参数进行验证。结果表明,基于性能影响对策优化后的化学实验室气流组织良好,满足排风柜设计使用和实验室化学暴露控制要求。

A Recent Study of Seasonal and Interannual Climate Variability over the Eastern Mediterranean Region

The present work aims to investigate seasonal and interannual climatic variability over the eastern Mediterranean (EM) region through the period (1949-2016). The monthly data of meteorological elements of temperature, pressure and precipitation for the EM region during the period (1949-2016) has used and analyzed. Moreover, the monthly NCEP/NCAR reanalysis data composites for these meteorological elements over the EM region have used. The seasonal and interannual variability of meteorological elements (surface air temperature, air temperature at 1000 hpa level, 500 hpa level, 500 hpa geopotential height, mean sea level pressure and precipitation) over the EM region during that period is studied. The anomaly, time series and correlation coefficient techniques, methods used for the data analysis. The results revealed that the climate variability of the EM region varied dramatically from season to season and from year to year through the period of study (1949-2016). There is a seasonal positive trend of temperature at 1000 hpa and 500 hpa levels and Geopotential height of 500 hpa level over the EM region. Meanwhile, it found a seasonal negative trend of mean sea level pressure and precipitation rate. For the interannual climatic variable over the EM region, it noticed that there was a positive trend of annual air temperature at the levels of 1000 hpa and 500 hpa. Meanwhile, there exists an annual negative trend anomaly of mean sea level pressure, 500 hpa geopotential height and precipitation rate over the EM region through the study period. It has become clear that the climate regime over the EM region is a complex regime.

绝热-近等温压缩空气耦合储能过程热压匹配规律

利用液体活塞机构强化储能过程压缩空气与环境的热量传递,可以有效降低压缩热耗散,提升储能过程电能向空气压力势能的转换效率。考虑到绝热压缩与近等温压缩空气储能的优势,本工作将近等温压缩与绝热压缩方式进行合理融合提出了复合压缩空气储能,通过建立不同压缩空气方式的热力计算模型,深入分析了绝热压缩与近等温压缩耦合作用下的高效储能特征,澄清了近等温压缩对储能系统高效运行的驱动机制。研究结果表明:复合压缩空气储能过程的㶲效率高于传统绝热压缩空气储能;同时,近等温压缩空气对复合压缩空气储能性能的影响较为显著,即变压排气液体活塞近等温压缩空气储能的㶲效率比恒压排气高3%,且变排气压工况下能够更好适应储气室内压力的变化,弱化储气室充气过程的温度效应;近等温压缩空气过程增加喷淋能够使㶲效率提升3.3%,且不同时段喷淋对液体活塞近等温压缩空气效能的影响具有较大差异。

变温水毯垫预防肩关节镜手术压力性损伤的效果研究

目的探讨变温水毯垫预防肩关节镜手术压力性损伤的效果。方法选择2020年10月至2022年10月于我院行肩关节镜手术的患者135例,随机分为三组各45例。术中,对照组应用防护垫减轻受压部位的压力,研究1组和研究2组应用变温水毯垫减轻局部压力,并分别控制肩髋部温度在35.5℃、37.5℃。比较三组的压力性损伤发生率和满意度。结果研究2组的压力性损伤发生率为2.22%,低于研究1组的15.56%和对照组的26.67%(P<0.05)。研究2组的CBA评分高于研究1组和对照组(P<0.05)。结论在肩关节镜手术中应用变温水毯垫控制肩髋部温度在37.5℃可显著降低压力性损伤发生率,提高患者的满意度。

高空作业平台摆动电液系统改进设计

针对高空作业平台摆动控制速度不可调和微动性差的问题,通过设计可叠加的分流阀组,使得控制器可以根据手柄偏离中位的倾斜角度选择相应数量的分流模块进行分流,以调节流入摆动油缸的流量,使油缸驱动吊篮摆动的速度与手柄偏离中位的倾斜角度适配,从而采用开关量控制的方式对摆动油缸运动速度实施分级离散控制。改进后的平台摆动系统安全可靠,具有较好的可控性和微动性。系统采用恒压变量系统,可以按需要的流量自动调整排量,提高了摆动系统的节能性。

恒温发酵和变温发酵对雪茄烟叶品质的影响

该研究通过恒温发酵明确不同温度对烟叶品质的影响规律,在此基础上进行三段式变温发酵,根据理化指标、致香成分和感官评吸确定最佳组合发酵温度。结果表明,恒温发酵实验组中低温发酵(35℃)组的总糖、还原糖和致香成分含量较高,分别为0.57%、0.25%和3.11 g/kg,可改善香韵丰富度,而高温发酵组的蛋白质和生物碱含量较低,分别为5.65%和3.22%,对刺激性具有改善作用。三段式变温发酵可显著提升香韵丰富度,降低刺激性。相较恒温35℃发酵,35℃-40℃-45℃和35℃-45℃-40℃发酵组的总氮含量分别降低了18.6%和21.7%,生物碱含量分别降低了5.7%和28.8%,总糖含量分别提高了28.1%和56.1%,致香成分总含量分别提高了21.9%和4.1%。低-高-中(35℃-45℃-40℃)和低-中-高(35℃-40℃-45℃)三段式发酵可有效弥补恒温发酵的不足,提高国产雪茄烟叶的品质。

变流量空气源热泵集中供暖系统水泵及末端控制方法研究

本文建立了变流量空气源热泵建筑供暖的数学模型,利用该模型研究了不同水泵控制方式下空气源热泵系统的性能。结果表明:为了使热泵机组保持较高的性能,其最小经济流量为额定流量的30%;3种控制方式中,供回水干管压差控制水泵功耗最大,最不利末端支路压差控制水泵功耗最小;相比于供回水干管压差控制,最不利末端支路压差控制水泵可节能0~31.84%;3种控制方式中,温差控制系统总功耗始终最大,最不利末端压差控制最小,它们的差值平均值在高负荷率下达到6.20%;压差控制和温差控制均可满足建筑供暖需要,但压差控制室内温度波动更小,适合用于对室内温度要求较高的场所。

斜盘式恒压变量柱塞泵动态特性研究

该文针对变量泵压力控制元件对变量泵的压力输出特性进行研究,通过模拟仿真研究压力控制阀上阻尼孔尺寸和弹簧刚度的影响规律。研究结果表明阻尼孔尺寸增加,减小变量泵输出压力的稳定时间,同时增大变量泵的泄漏量,压力输出偏差也会增大;调压弹簧刚度增加导致变量泵压力响应速度降低,同时泵的输出压力偏差会有所增大。

煤层气井两层合采气水同产井底流压计算方法

井底流压是确定煤层气井合理工作制度,进而实现长期稳产的关键影响因素。针对定质量模型不考虑储集层段加速度压降和不同井段质量变化导致不符合两层合采特性,以及采用下部储集层井底流压作为2个储集层井底流压来调节生产制度导致不符合上部储集层调节需求的问题,对加速度压降表达式进行了分解和推导,建立了其与单位长度径向流量的关系式,推导了含径向流入的储集层段压降公式;将储集层分成多个微元段,建立了每个微元段的压降计算方法;根据各井段气水流量,推导了相应的气相和水相速度计算方程;将上述方程结合,建立了变质量模型。将生产数据分别代入变质量模型和定质量模型,气水同产时,变质量模型的误差为2.96%~6.67%,定质量模型的误差为7.33%~15.10%,变质量模型更加准确。2个储集层的井底流压相差较大,最大相差47.3%,因此需要根据各自的井底流压调节生产制度。变质量模型能够准确给出合采各层的井底流压,更符合现场实际,同时也避免了采用相同井底流压导致无法精准调节2个储集层生产制度的问题,从而为制定最优化排采制度、实现高产稳产提供技术支撑。

改进PSO-BPNN供水泵站变频恒压PID控制

供水泵站是变频恒压系统,要求保障水压稳定,且在干扰情况下能快速响应并恢复稳定。为提升系统稳定性、高效性,提出一种改进PSO-BPNN的PID控制方法。首先构建供水泵站变频恒压控制模型,再基于BPNN实现PID非线性控制,提出一种PSO惯性权重改进策略,以提升PID参数的计算效率,从而更好地满足供水泵站控制需求。实验表明,本文算法响应快速、无超调,且具有稳定的非线性信号跟踪性能。相比BPNN、PSO-BPNN的两种PID控制算法,本文算法在恒压实验的调节时间缩短了29.6%和2.8%;在干扰实验中,超调量减少了34.6%和19.9%,稳定时间缩短了7.3%和1.6%。本文算法可提升供水泵站系统的稳定性和高效性。