Valve Dynamic and Thermal Cycle Model in Stepless Capacity Regulation for Reciprocating Compressor

The existing researches of stepless capacity regulation system by depressing the suction valve for reciprocation compressor always adopt hypothesis that the compressor valves are open or close instantaneously, the valve dynamic has not been taken account into thermal cycle computation, the influence of capacity regulation system on suction valves dynamic performance and cylinder thermal cycle operation has not been considered. This paper focuses on theoretical and experimental analysis of the valve dynamic and thermal cycle for reciprocating compressor in the situation of stepless capacity regulation. The valve dynamics equation, gas forces for normal and back flow, and the cylinder pressure varying with suction valve unloader moment during compression thermal cycle are discussed. A new valve dynamic model based on L-K real gas state equation for reciprocating compressor is first deduced to reduce the calculation errors induced by the ideal gas state equation. The variations of valve dynamic and cylinder pressure during part of compression stroke are calculated numerically. The calculation results reveal the non-normal thermal cycle and operation condition of compressor in stepless capacity regulation situation. The numerical simulation results of the valve dynamic and thermal cycle parameters are also verified by the stepless capacity regulation experiments in the type of 3L-10/8 reciprocating compressor. The experimental results agree with the numerical simulation results, which show that the theoretical models proposed are effective and high-precision. The proposed theoretical models build the theoretical foundation to design the real stepless capacity regulation system.

Study on the driving factors and regulation mode for coal production capacity

Coal production capacity regulation is a complex system involving economic growth,structural optimization,high-efficiency mining,and environmental protection.Based on its driving factors,this paper forms four regulation modes representing different control orientations,establishes a system dynamics model,and predicts the regulation effects of single-factor and combined control mode.The result shows:(1) Except for the mechanization degree and recovery rate,the other nine individual production capacity control policies are all conducive to reducing coal production capacity and restraining the excessive growth of coal production capacity.(2) The effect of combined regulation mode on slowing down the growth of coal demand,regulating the excessive growth of coal production capacity and new capacity investment are obviously better than that of single policy.(3) The combined control modes have obvious differences in the suppression effect on coal production capacity:transformational development mode > technology-driven mode > structural optimization mode > efficiency improvement mode.Therefore,in the process of achieving optimal regulation of coal production capacity,attention should be paid to the preferential use of transformational development and technology-driven mode.At the same time,the comprehensive use of regulation and control methods should also be considered to improve the regulation effect and the regulation efficiency of coal production capacity.

Regulation and Genetic Analysis of Leaf Source Capacity in Rice

The highest value of photosynthetic rate and active photosynthesis duration in flag leaves could be increased in a range of 3.55% and 3 d by dressing N (112.5 kg/ha) at heading stage in hybrid rice variety cv. Shanyou63 compared with control (no dressing N at heading), respectively. This resulted in the 7.93 percentage and 5.70 percentage increases of its leaf source capacity (LSC) and yield, respectively. Furthermore, genetic analysis of LSC was made by 4 × 4 incomplete diallel cross-design with 4 sterility lines and 4 resilience lines. The results showed that hB2 and hN2 in LSC for rice were higher than 70 percentage and 30 percentage, respectively, suggesting that it may be used as an index for selecting varieties with high photosynthetic efficiency in rice breeding. There were the similar effects of the additive and non-additive variations on LSC in hybrid rice. LSC was mainly influenced by sterility line and resilience interactions. The adding effect value of general combining ability for its parents may be used to forecast the phenotype of LSC in hybrid rice.

Impact of the Three Gorges Dam on Regulation and Storage Capacity of Poyang Lake

The regulation and storage capacity of Poyang Lake is infl uenced by the fl ow from the main stream of the Yangtze River and the fi ve rivers in the Poyang Lake basin.After the operation of the Three Gorges Dam(TGD),hydrological changes in the main stream of the Yangtze River impact water exchange between the Yangtze River and Poyang Lake.Based on the analysis of measured data and factors infl uencing outfl ow at Hukou station,a new empirical formula describing outfl ow at Hukou station and critical water level for lake storage capacity is established.The change in monthly storage capacity of Poyang Lake before and after the construction of the TGD is analyzed quantitatively.The results show that the fl ows from the main stream of the Yangtze River and the fi ve rivers in the Poyang Lake basin affect outfl ow and water storage capacity by changing the water level difference between Xingzi and Hukou stations and by changing the water level at Hukou station.But the Yangtze River and the fi ve rivers in the Poyang Lake basin differ in process and degree.If the water level at Hukou station remains consistent,when the fl ow from the fi ver rivers increases by 1,000 m3/s,the outfl ow at Hukou station increases by 304 m3/s.When the fl ow from the main stream of the Yangtze River increases by 1,000 m3/s,the outfl ow at Hukou station decreases by 724 m3/s.In addition,the operation of the TGD affects the water storage capacity of Poyang Lake.The water volume of Poyang Lake decreases by 49.4%in September,but increases by 47.7%in May.

Non-Euclidean Geometry and Regulated Characteristics of Limited Capacity Power Supply

The restriction of load power, two-valued regulation characteristic, and interference of several loads are observed in power supply systems with a limited capacity of voltage sources. In this paper, the definition of regime in an invariant form through different parameters, of changes of transformation ratio and voltage load is grounded for these circuits with two loads. The approach for interpretation of changes or ＂kinematics＂ of load regime is presented by using the conformal and hyperbolic plane. To simplify the task and reveal the basic moments of influence of the limited source power, the static regulation characteristics and idealized models of voltage converters are considered. Geometrical interpretation of a simplified model of multichannel power supply system allows basing the definition of operating regime parameters. Results can be useful for electric circuit theory education and for voltage coordinated control of given loads. Non-Euclidean geometry is a new mathematical apparatus in the electric circuit theory, adequately interprets ＂kinematics＂ of circuit, and provides a validation for the introduction and definition of the proposed concepts. From the methodological point, the presented approach is applied for a long time in other scientific domains, as mechanics and biology.

Does Environmental Regulation Weaken Industrial Competitiveness?Inspirations from China’s Iron and Steel Sector

China＇s economic growth is heavily influenced by exports, while reconciling environmental regulation and economic growth requires handling the relationship between environmental regulation and industrial competitiveness well. The effects of environmental regulation on industrial competitiveness are largely subject to the institutional design of environmental regulation. Despite numerous studies on the relationship between environmental regulation and industrial competitiveness, a consensus has yet to be reached. Aside from differences in research methodology, these studies failed to give sufficient consideration to the impact of environmental regulation on industrial competitiveness. Such effects can be negative or positive depending on the design of environmental regulatory policy. This paper has investigated the relationship between environmental regulation and the competitiveness of China＇s iron and steel industry and discovered that tighter environmental regulation does not diminish the competitiveness of the iron and steel industry since the policy design of environmental regulation accommodates the tolerance of advanced production capacity and includes a reasonable cost sharing mechanism. This discovery is of important reference for China to develop rational policy design to balance the relationship between environmental regulation and industrial competitiveness.

Experimental Investigation of Capacity Control Scheme on System Performance for a Machine Tool Cooler

Highly accurate manufacture in machining industry can only be obtained with precise temperature control of the coolant （oil or water）.Machine tool with more accurate,stable and advanced the precision of the working component cannot be developed without appropriate cooling.However,the machine tool coolers are facing the control hunting of cooling temperature and the dramatic variation of heat load in high-accuracy machining.The main objective of this study is to evaluate the influence of the hot-gas by-pass scheme and suction regulation for capacity control of a machine tool cooler system.In this study,experimental investigation on both hot-gas by-pass scheme and suction valve regulation for capacity control has been proposed.Effects of using capillary tube and thermostatic expansion valve along with different capacity control scheme have been investigated extensively in an environmental testing room.Cooling performance and power consumption of the cooler system have been measured and analyzed as well by comparing with different opening percentage of throttling valve under specific coolant temperature.The experimental results reveal that the power consumption will reduce slightly by capacity control using the hot-gas by-pass scheme but the coefficient of performance （COP） of the overall system will decrease.Lower coolant temperature will result in higher compressor power consumption as well.While conducting suction valve regulating for capacity control,energy-saving at 10%-12% can be obtained by using thermostatic expansion valve under different evaporator load.It also reveals that suction valve regulation along with adequate choice of thermostatic expansion valve can provide alternative choice for steady capacity control and substantial energy-saving.The proposed cooler systems with different capacity control schemes are not only more cost-effective than inverter driven system,but also can perform energy-saving and precise temperature control specific for high-accuracy machine tool cooling.

Study on Production Regulation of Reservoir under Different Demand

Natural gas production is related to the demand for gas, which is low in summer and high in winter. While the gas storage is still being demonstrated and constructed, oil and gas fields should formulate and implement production control schemes suitable for gas reservoirs. The realization of natural gas production can not only meet the demand of gas consumption, but also ensure the scientific and efficient development of gas reservoirs, and meet the needs of dynamic analysis of gas reservoirs at different development stages and scientific research of gas reservoirs. In this paper, KAPPA Workstation 5.20 software is used to determine the inflow dynamic model of a single well. The nodal method is used to determine the reasonable production and peak shaving capacity in combination with the critical fluid carrying capacity of gas wells and the erosion rate of gas wells. The reasonable production allocation in each period, i.e. the production control scheme, is obtained. It solves the scientific and efficient development of natural gas in X gas field, which is still under the construction of gas storage, and provides guidance for gas reservoir development management and regulation.

A Nonlinear Flow Control Scheme Under Capacity Constraints

We present a nonlinear flow control scheme based on a buffer management model with physical constraints. It extends previous result of Pitsillides et al. in [6] by improving the queue length regulation for better service of network traffics. Besides a single node system, we also address the decentralized control of many cascaded nodes. The proposed discontinuous controller asymptotically regulates the buffer queue length at the output port of a router/switch to a constant reference value, under unknown time varying interfering traffics and saturation constraints on control input and states. Its continuous approximation achieves practical regulation with an ultimate bound on the regulation error tunable by a design parameter.

Dynamic discharging characteristics of absorption thermal battery under different capacity regulation strategies

Thermal battery plays an important role in renewable energy utilization towards carbon neutrality.The novel absorption thermal battery(ATB)has excellent performance but suffers from serious capacity attenuation.To address this problem,two capacity regulation methods,i.e.,variable solution flow and variable cooling water flow,are proposed to achieve a demanded discharging rate.The effects of the two regulation strategies on the dynamic discharging characteristics and overall storage performance are comparatively investigated.To demon-strate the adjustability of the output capacity,several stable discharging rates are successfully maintained by the proposed methods.To maintain a higher discharging rate,the stable discharging time has to be sacrificed.As the demanded output increased from 0.5 kW to 6.0 kW,the stable discharging time decreased from 781.8 min to 27.9 min under variable solution flow and from 769.9 min to 30.7 min under variable cooling water flow.With the increase of solution or water flow rate,the energy storage density is improved,while the energy storage efficiency is slightly increased first and decreased later.The regulation method of variable water flow shows relatively lower energy storage efficiency due to the larger pump power.This study could facilitate reasonable development and application of ATB cycles.

黄河下游花园口以上河段滞沙能力分析

黄河下游河床调整主要取决于来水来沙和河床边界条件,河床调整沿程不均衡特征明显,花园口以上河段床演变对水沙条件的变化响应尤为突出,泥沙冲淤调整幅度最大。基于河道冲淤及水沙演进特性、滞沙可行性、河槽几何特性等分析,提出了花园口以上河段可作为泥沙天然反调节“库”概念,结合黄河下游实测洪水资料,采用水力计算方法,计算了花园口以上河段的河槽排洪能力及不同河槽规模条件下河槽允许滞沙量,提出了反调“库”滞沙能力,可为小浪底水库排沙指标的确定提供依据,对维持小浪底水库有效库容、弥补后续清水河床沙源不足、改善黄河下游河槽冲淤不均衡现象具有重要意义。

退役运动员职业转换力研究:概念维度构建、量表开发和实证检验

职业转换力是退役运动员顺畅实现职业转换的关键因素。通过文献资料法、行为事件访谈法等构建退役运动员职业转换力的理论概念维度,并结合质性研究结果开发测试量表,通过问卷调查法、数理统计法等量化研究方法进行交互检验。研究认为:(1)基于无边界职业生涯视角提出退役运动员职业转换力是指应对职业转换而采取行动、更好适应新职业的个体能力。(2)退役运动员职业转换力量表包含能力拓展、生涯管理、适应调节3个维度共16个题项,退役运动员职业转换力的二阶三因子测量模型拟合优度较好,具备较好的信度和效度,与其理论概念维度保持一致。(3)预测效应显示退役运动员职业转换力能显著提高就业质量,同时促使其表现出较高的职业满意度。

数字金融发展与企业产能利用率:基于沪深A股上市公司的实证研究

基于2011—2021年A股上市公司样本数据,探讨数字金融发展对企业产能利用率的影响机理。研究发现,数字金融发展能够显著提高企业的产能利用率,促进技术创新、改善资源错配和抑制过度投资是数字金融发展提高企业产能利用率的作用渠道。异质性分析发现,数字金融发展对企业产能利用率的提升作用在融资约束较大企业、高科技企业及市场化程度较低地区企业中表现得更为明显。适当的金融监管能够引导数字金融正外部性的发挥,助力数字金融发展对企业产能利用率的提升作用。据此提出大力推进数字金融发展、深化供给侧结构性改革、增强数字金融监管力度和提升企业质量管理能力等政策建议。

万家寨水库运行以来调洪库容变化规律及恢复措施研究

为了给万家寨水库调洪库容有效恢复提供科技支撑,系统梳理了万家寨水库入出库水沙变化情况、库区泥沙冲淤演变规律、调洪库容变化规律以及淤损库容恢复措施,结果表明:1)万家寨水库1999—2023年非汛期运行水位为952~980 m,1999—2010年汛期运行水位为950.9~967.2 m、2011—2023年(除2016年外)汛期降低水位运用后最低水位为921.6 m;2)万家寨水库1999—2023年多年平均入库水量约为185.19亿m^(3)、沙量约为0.501亿t,出库水量约为180.70亿m^(3)、沙量约为0.363亿t;3)万家寨水库2010年汛后淤积纵剖面基本达到设计淤积平衡状态;2011年以来水库排沙运用,截至2023年10月总库容淤损2.859亿m^(3)、调洪库容淤损0.191亿m^(3);4)万家寨水库入库长历时大流量过程有利于降低水位敞泄运用排沙,坝前水位低于952.00 m时出库含沙量迅速增加,降至淤积面以下或泄空敞泄时,产生的溯源冲刷有利于提高输沙效率;5)单纯依靠水力减淤已无法有效恢复万家寨水库调洪库容,可采用水力减淤与机械清淤相结合的方式减淤,清淤泥沙输送至主河槽随水流动力排出库区或输送至岸上进行泥沙综合利用。

感潮河段江滩湿地水体交换模拟与调控措施研究

保障湿地水体交换能力对完善湿地功能,维持湿地生态系统的健康至关重要。南京绿水湾湿地是长江江滩湿地,具备多种湿地特点,动力条件复杂。以绿水湾湿地为研究对象,通过构建二维水动力―水龄耦合数学模型,模拟了现状和不同闸、泵调控措施下各区域的水动力特征及水体交换能力。结果表明:现状工况湿地内部水面覆盖率低,水体交换能力差,大部分区域水体交换时间在7 d以上,甚至是14 d以上;建闸后虽然增加了枯季的水面覆盖率,但明显减弱了湿地内水动力,延长了各区域换水周期,换水周期大于14 d的区域明显增多;补水泵站的运用整体上缩短了大部分区域的换水周期,使得水域流速大于0.010 m/s的区域面积明显增加,换水周期大于14 d的区域面积减少。建闸蓄水后,为预防藻类暴发,需控制湿地内水体的换水周期在14 d内,结合各区域水动力和水体交换特点,提出了闸门生态调度、布置净水能力较强的挺水或沉水植物、增设补水点等调度策略。

适应新型电力系统的电力互替品市场——(二)商品形态及形成机理

当前的电力现货市场基础理论是在新能源占比极低情况下提出的,其所依据的“分时交易”假设无法适应新型电力系统新能源占比日渐趋高、调节需求日益增加的新情况。为此,文中舍弃“分时交易”的基本假设,将功率曲线作为有机整体进行交易,探讨商品形态及形成机理。首先,分析对比“分时交易”与系列论文提出的“整体交易”中商品的形态,揭示“分时交易”中电力商品在各时段同质的假设在实际中不能成立的根本原因。其次,从市场组织者角度出发,探讨电力互替品的性质与形成过程,指出电力除具备生产使用价值外,还具有平衡价值,并定义互替电量、调节电量分别对这两种价值进行表征与量化。进而,从市场主体角度出发,以电力互替品的形成成本最小为目标,提出市场主体自主优化形成电力互替品的方法。进一步指出,各主体还可互补聚合形成电力互替品,适应海量分散的新型市场主体进入市场。最后,算例从量、质、价三个方面展示电力互替品的形成过程,分析了影响电力互替品形成成本的关键因素。电力互替品的形成过程,正是市场主体从计划式的“被动提供灵活性”变为市场化的“主动提供灵活性”的过程,也正是系统调节能力的挖掘提升过程。

考虑核电灵活参与调峰的多源联合运行低碳经济调度

在含高比例核电机组和新能源发电设备的沿海地区电网,系统调峰压力严峻。为了满足系统调峰需求,充分挖掘核电调峰潜力,建立核电灵活出力参与调峰的核-光-储-蓄-火联合运行优化调度模型。首先,针对核电灵活出力的非线性特性,采用0-1变量进行线性化有效约束;然后,充分考虑各电源的运行特性及成本,建立完整的系统运行约束;最后,在传统的以经济调度为优化目标的基础上,引入不同碳交易机制,并兼顾系统新能源消纳水平。算例分析验证了模型的有效性,结果表明,所提优化调度模型充分实现了核电的灵活出力,有效缓解了系统调峰压力,减少常规火电机组的频繁启停,并有效提高了新能源的消纳水平,使系统运行更加经济性和低碳性。

不同调节能力水库对洪水四要素的影响分析

本文基于26个水库工程建库前后下游洪水四个要素的变化情况,分析不同调节能力水库对下游洪水的影响程度。结果表明,多年、年、季月调节水库总体对洪水首次出现时间有滞后作用、对洪水出现次数有大幅消减作用;周日调节水库对首次洪水出现时间影响不明显,且增加了下游洪水出现频次;同调节能力、不同流域的水库对下游洪水的影响程度与水库占流域面积比无明显线性关系。

生态水文系统支撑城市韧性安全建设的若干思考

近40年城市生态水文学应用研究的重要进展,特别是区域水循环要素的优化调控,有效地支撑了韧性安全城市建设。在城市生态水文系统理念的指导下,北美、欧洲和中国相继出现了低影响开发、水框架指令、海绵城市与气候适应型城市建设。全球变化和人为活动相互作用产生了复杂的城市生态水文过程,自然水循环模式已转变为“自然-社会”相互作用的二元水循环模式。面对全球变化,韧性安全城市的建设更加关注对气候变化的减缓和适应,特别是对极端天气气候事件的适应能力。我国长期持续大规模的城市开发建设,强烈影响和改变着区域水循环关键要素,城市地下空间开发利用和地面沉降面临着极端天气气候情境下的灾害风险。因此,地学基础条件及其韧性构成了城市韧性安全底座的基础。基于二元水循环关键要素调控设计的减缓和适应对策,在新一轮气候适应型城市建设中发挥了重要作用。“气候变化—区域二元水循环—水平衡调控—灾害风险”“遥感大数据—台站网小数据—传递函数—云孪生”,可作为一种地球大数据支撑韧性城市建设与可持续发展的技术框架和方法组合。上海作为长江流域的龙头和海陆交互敏感区域,城市韧性安全还面临着海平面上升的考验。在气候变化情景下区域二元水循环关键要素调控,可作为地学服务上海地下空间安全及城市韧性安全的一个策略。

四川省气电容量成本回收机制研究

四川省发展气电是实现“双碳”目标,提升电力调峰调频、确保安全稳定供电的重大举措。2022年四川省出台气电上网两部制电价政策指导意见,明确气电容量电价按一定合理收益回收固定投资成本,电量电价与气价实施联动调整。通过梳理国家及部分省份的气电两部制电价政策,调查分析四川气电的成本构成,研究对气电投资成本回收机制并测算容量电价,提出了容量电价测算原则、方法以及疏导路径的相关建议。研究结果表明:①因地制宜出台气电价格政策有利于推动气电产业健康可持续发展;②实施气电两部制电价有利于通过容量电价回收固定成本且取得合理收益,有利于促进四川气电产业有序健康可持续发展,并通过相对较低的电量电价实现与电力市场逐步接轨,增强市场竞争力;③容量电价按照“谁受益、谁承担”和“合理分摊、动态调整”原则进行疏导;④气电容量电价标准按资本金内部收益率8%对应取值,F机组容量电价标准可为28元/(kW·月),并且容量电费由该省内大工业、一般工商业用户疏导分摊。